AI Trajectory

Trajectory: (Expand/Collapse All)
Seq	Timestamp	Type	Name	Duration
0/0	2026/09/15 07:27	flow	patch-triage	25m Args: null Results: { "EnableConfigs": [ "MODULES", "MEM_ALLOC_PROFILING", "SYSFS", "KALLSYMS", "PROC_FS" ], "FocusSymbols": [ "allocate_codetag_sections", "layout_and_allocate", "move_module", "apply_relocations", "layout_symtab", "add_kallsyms", "add_sect_attrs", "add_notes_attrs", "codetag_alloc_module_section", "codetag_free_module_sections", "codetag_load_module", "codetag_unload_module", "reserve_module_tags", "release_module_tags", "vm_module_tags_populate", "shutdown_mem_profiling" ], "KMSANReasoning": "The patch series refactors module loading for standalone sections (.data..percpu and codetag sections like alloc_tag), handling fallback when contiguous codetag memory overflows, adjusting module section layout and relocation logic, deferring /proc/allocinfo removal via a workqueue to avoid deadlocks, and cleaning up error unwinding paths in vm_module_tags_populate().\n\n- KASAN \u0026 standard detector applicability: The changes touch module section memory allocation, life-cycle management, error unwinding, and sysfs/procfs registrations. Potential bugs in these areas include out-of-bounds accesses during section layout/relocation, use-after-free / double-free during codetag unload or error rollback, and deadlocks in shutdown paths. These risks are fully covered by KASAN, LOCKDEP, and kmemleak.\n- KMSAN applicability: KMSAN detects uninitialized memory reads and kernel-to-user info-leaks. In this patch series, newly allocated standalone sections are completely initialized via memcpy() or memset() depending on section type (SHT_NOBITS). Sysfs attribute structures are allocated using kzalloc_flex() and kzalloc_objs() which zero memory. No conditional branches rely on uninitialized data, and no uninitialized padding or buffer content is exposed to userspace.\n\nTherefore, running a dedicated KMSAN session is not warranted.", "NeedsKMSAN": false, "Reasoning": "The patch series refactors core module loading, section layout handling (introducing SH_ENTSIZE_STANDALONE for per-CPU and codetag sections), and memory allocation profiling error handling and cleanup paths (mm/alloc_tag.c and lib/codetag.c). It modifies module allocation and relocation flows, adds error rollback in vm_module_tags_populate and reserve_module_tags, and alters module loading behaviors when codetag capacity is exhausted. These changes are reachable in standard virtualized environments via module loader syscalls (init_module, finit_module) and procfs/sysfs interactions.", "WorthFuzzing": true }
1/1	2026/09/15 07:27	action	read-patch-diff	0m Args: null Results: { "PatchDiff": "commit 24d9f5e60beaa38a9de84cd878030514129be9c5\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate: Tue Sep 15 07:27:34 2026 +0000\n\n syz-cluster: applied patch under review\n\ndiff --git a/include/linux/module.h b/include/linux/module.h\nindex 96cc98568eea5..0c6f32ddcbf2d 100644\n--- a/include/linux/module.h\n+++ b/include/linux/module.h\n@@ -325,6 +325,8 @@ enum mod_mem_type {\n \tMOD_INIT_RODATA,\n \n \tMOD_MEM_NUM_TYPES,\n+\n+\tMOD_STANDALONE = -2,\n \tMOD_INVALID = -1,\n };\n \ndiff --git a/kernel/module/internal.h b/kernel/module/internal.h\nindex 061161cc79d90..4c738074a27b8 100644\n--- a/kernel/module/internal.h\n+++ b/kernel/module/internal.h\n@@ -29,6 +29,14 @@\n #define SH_ENTSIZE_TYPE_MASK\t((1UL \u003c\u003c SH_ENTSIZE_TYPE_BITS) - 1)\n #define SH_ENTSIZE_OFFSET_MASK\t((1UL \u003c\u003c (BITS_PER_LONG - SH_ENTSIZE_TYPE_BITS)) - 1)\n \n+/\n+ Marker for sections with a separate allocation, which are not placed\n+ * into mod-\u003emem[].\n+ /\n+#define SH_ENTSIZE_STANDALONE\t\t\t\t\t\\\n+\t(((unsigned long)MOD_STANDALONE \u0026 SH_ENTSIZE_TYPE_MASK)\t\\\n+\t \u003c\u003c SH_ENTSIZE_TYPE_SHIFT)\n+\n / Maximum number of characters written by module_flags() /\n #define MODULE_FLAGS_BUF_SIZE (TAINT_FLAGS_COUNT + 4)\n \ndiff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c\nindex f23126d804b25..0dca6d40160e5 100644\n--- a/kernel/module/kallsyms.c\n+++ b/kernel/module/kallsyms.c\n@@ -76,7 +76,7 @@ static char elf_type(const Elf_Sym sym, const struct load_info info)\n }\n \n static bool is_core_symbol(const Elf_Sym src, const Elf_Shdr sechdrs,\n-\t\t\t unsigned int shnum, unsigned int pcpundx)\n+\t\t\t unsigned int shnum)\n {\n \tconst Elf_Shdr sec;\n \tenum mod_mem_type type;\n@@ -86,11 +86,6 @@ static bool is_core_symbol(const Elf_Sym src, const Elf_Shdr sechdrs,\n \t !src-\u003est_name)\n \t\treturn false;\n \n-#ifdef CONFIG_KALLSYMS_ALL\n-\tif (src-\u003est_shndx == pcpundx)\n-\t\treturn true;\n-#endif\n-\n \tsec = sechdrs + src-\u003est_shndx;\n \ttype = sec-\u003esh_entsize \u003e\u003e SH_ENTSIZE_TYPE_SHIFT;\n \tif (!(sec-\u003esh_flags \u0026 SHF_ALLOC)\n@@ -131,8 +126,7 @@ void layout_symtab(struct module mod, struct load_info info)\n \t/* Compute total space required for the core symbols' strtab. /\n \tfor (ndst = i = 0; i \u003c nsrc; i++) {\n \t\tif (i == 0 \|\| is_livepatch_module(mod) \|\|\n-\t\t is_core_symbol(src + i, info-\u003esechdrs, info-\u003ehdr-\u003ee_shnum,\n-\t\t\t\t info-\u003eindex.pcpu)) {\n+\t\t is_core_symbol(src + i, info-\u003esechdrs, info-\u003ehdr-\u003ee_shnum)) {\n \t\t\tstrtab_size += strlen(\u0026info-\u003estrtab[src[i].st_name]) + 1;\n \t\t\tndst++;\n \t\t}\n@@ -199,8 +193,7 @@ void add_kallsyms(struct module mod, const struct load_info info)\n \tfor (ndst = i = 0; i \u003c kallsyms-\u003enum_symtab; i++) {\n \t\tkallsyms-\u003etypetab[i] = elf_type(src + i, info);\n \t\tif (i == 0 \|\| is_livepatch_module(mod) \|\|\n-\t\t is_core_symbol(src + i, info-\u003esechdrs, info-\u003ehdr-\u003ee_shnum,\n-\t\t\t\t info-\u003eindex.pcpu)) {\n+\t\t is_core_symbol(src + i, info-\u003esechdrs, info-\u003ehdr-\u003ee_shnum)) {\n \t\t\tssize_t ret;\n \n \t\t\tmod-\u003ecore_kallsyms.typetab[ndst] =\ndiff --git a/kernel/module/main.c b/kernel/module/main.c\nindex c1b34dc1e89ac..b7ebcc40bddab 100644\n--- a/kernel/module/main.c\n+++ b/kernel/module/main.c\n@@ -1619,12 +1619,13 @@ static int apply_relocations(struct module mod, const struct load_info info)\n \n \t\t/\n \t\t * Don't bother with non-allocated sections.\n-\t\t * An exception is the percpu section, which has separate allocations\n-\t\t * for individual CPUs. We relocate the percpu section in the initial\n-\t\t * ELF template and subsequently copy it to the per-CPU destinations.\n+\t\t \n+\t\t Note that .data..percpu has separate allocations for\n+\t\t * individual CPUs. We relocate the section in the\n+\t\t * initial ELF template and subsequently copy it to the\n+\t\t * per-CPU destinations.\n \t\t /\n-\t\tif (!(info-\u003esechdrs[infosec].sh_flags \u0026 SHF_ALLOC) \u0026\u0026\n-\t\t (!infosec \|\| infosec != info-\u003eindex.pcpu))\n+\t\tif (!(info-\u003esechdrs[infosec].sh_flags \u0026 SHF_ALLOC))\n \t\t\tcontinue;\n \n \t\tif (info-\u003esechdrs[i].sh_flags \u0026 SHF_RELA_LIVEPATCH)\n@@ -1715,27 +1716,13 @@ static void __layout_sections(struct module mod, struct load_info info, bool i\n \n \t\t\tif ((s-\u003esh_flags \u0026 masks[m][0]) != masks[m][0]\n \t\t\t \|\| (s-\u003esh_flags \u0026 masks[m][1])\n-\t\t\t \|\| s-\u003esh_entsize != ~0UL\n+\t\t\t \|\| s-\u003esh_entsize != ~0UL / offset or standalone /\n \t\t\t \|\| is_init != module_init_layout_section(sname))\n \t\t\t\tcontinue;\n \n \t\t\tif (WARN_ON_ONCE(type == MOD_INVALID))\n \t\t\t\tcontinue;\n \n-\t\t\t/\n-\t\t\t * Do not allocate codetag memory as we load it into\n-\t\t\t * preallocated contiguous memory.\n-\t\t\t /\n-\t\t\tif (codetag_needs_module_section(mod, sname, s-\u003esh_size)) {\n-\t\t\t\t/\n-\t\t\t\t * s-\u003esh_entsize won't be used but populate the\n-\t\t\t\t * type field to avoid confusion.\n-\t\t\t\t /\n-\t\t\t\ts-\u003esh_entsize = ((unsigned long)(type) \u0026 SH_ENTSIZE_TYPE_MASK)\n-\t\t\t\t\t\t\u003c\u003c SH_ENTSIZE_TYPE_SHIFT;\n-\t\t\t\tcontinue;\n-\t\t\t}\n-\n \t\t\ts-\u003esh_entsize = module_get_offset_and_type(mod, type, s, i);\n \t\t\tpr_debug(\"\\t%s\\n\", sname);\n \t\t}\n@@ -1745,16 +1732,10 @@ static void __layout_sections(struct module mod, struct load_info info, bool i\n /\n * Lay out the SHF_ALLOC sections in a way not dissimilar to how ld\n * might -- code, read-only data, read-write data, small data. Tally\n- * sizes, and place the offsets into sh_entsize fields: high bit means it\n- * belongs in init.\n+ * sizes, and place the offsets into sh_entsize fields.\n /\n static void layout_sections(struct module mod, struct load_info info)\n {\n-\tunsigned int i;\n-\n-\tfor (i = 0; i \u003c info-\u003ehdr-\u003ee_shnum; i++)\n-\t\tinfo-\u003esechdrs[i].sh_entsize = ~0UL;\n-\n \tpr_debug(\"Core section allocation order for %s:\\n\", mod-\u003ename);\n \t__layout_sections(mod, info, false);\n \n@@ -2800,7 +2781,6 @@ static int move_module(struct module mod, struct load_info info)\n {\n \tint i, ret;\n \tenum mod_mem_type t = MOD_MEM_NUM_TYPES;\n-\tbool codetag_section_found = false;\n \n \tfor_each_mod_mem_type(type) {\n \t\tif (!mod-\u003emem[type].size) {\n@@ -2820,34 +2800,13 @@ static int move_module(struct module mod, struct load_info info)\n \tfor (i = 0; i \u003c info-\u003ehdr-\u003ee_shnum; i++) {\n \t\tvoid dest;\n \t\tElf_Shdr shdr = \u0026info-\u003esechdrs[i];\n-\t\tconst char sname;\n \n-\t\tif (!(shdr-\u003esh_flags \u0026 SHF_ALLOC))\n+\t\tif (!(shdr-\u003esh_flags \u0026 SHF_ALLOC)\n+\t\t \|\| shdr-\u003esh_entsize == SH_ENTSIZE_STANDALONE)\n \t\t\tcontinue;\n \n-\t\tsname = info-\u003esecstrings + shdr-\u003esh_name;\n-\t\t/\n-\t\t Load codetag sections separately as they might still be used\n-\t\t * after module unload.\n-\t\t /\n-\t\tif (codetag_needs_module_section(mod, sname, shdr-\u003esh_size)) {\n-\t\t\tdest = codetag_alloc_module_section(mod, sname, shdr-\u003esh_size,\n-\t\t\t\t\tarch_mod_section_prepend(mod, i), shdr-\u003esh_addralign);\n-\t\t\tif (WARN_ON(!dest)) {\n-\t\t\t\tret = -EINVAL;\n-\t\t\t\tgoto out_err;\n-\t\t\t}\n-\t\t\tif (IS_ERR(dest)) {\n-\t\t\t\tret = PTR_ERR(dest);\n-\t\t\t\tgoto out_err;\n-\t\t\t}\n-\t\t\tcodetag_section_found = true;\n-\t\t} else {\n-\t\t\tenum mod_mem_type type = shdr-\u003esh_entsize \u003e\u003e SH_ENTSIZE_TYPE_SHIFT;\n-\t\t\tunsigned long offset = shdr-\u003esh_entsize \u0026 SH_ENTSIZE_OFFSET_MASK;\n-\n-\t\t\tdest = mod-\u003emem[type].base + offset;\n-\t\t}\n+\t\tdest = mod-\u003emem[shdr-\u003esh_entsize \u003e\u003e SH_ENTSIZE_TYPE_SHIFT].base +\n+\t\t (shdr-\u003esh_entsize \u0026 SH_ENTSIZE_OFFSET_MASK);\n \n \t\tif (shdr-\u003esh_type != SHT_NOBITS) {\n \t\t\t/\n@@ -2879,8 +2838,6 @@ static int move_module(struct module mod, struct load_info info)\n \tmodule_memory_restore_rox(mod);\n \twhile (t--)\n \t\tmodule_memory_free(mod, t);\n-\tif (codetag_section_found)\n-\t\tcodetag_free_module_sections(mod);\n \n \treturn ret;\n }\n@@ -2951,9 +2908,53 @@ static bool blacklisted(const char module_name)\n }\n core_param(module_blacklist, module_blacklist, charp, 0400);\n \n+/\n+ * Allocate codetag sections separately. They are loaded into preallocated\n+ * contiguous memory because they may still be used after the module is\n+ * unloaded.\n+ \n+ If the separate allocation overflows, allocate the section normally\n+ * so that the module can still be loaded.\n+ /\n+static int allocate_codetag_sections(struct load_info info)\n+{\n+\tfor (unsigned int i = 1; i \u003c info-\u003ehdr-\u003ee_shnum; i++) {\n+\t\tElf_Shdr shdr = \u0026info-\u003esechdrs[i];\n+\t\tconst char sname = info-\u003esecstrings + shdr-\u003esh_name;\n+\t\tvoid dest;\n+\n+\t\tif (!codetag_needs_module_section(info-\u003emod, sname, shdr-\u003esh_size))\n+\t\t\tcontinue;\n+\n+\t\tdest = codetag_alloc_module_section(info-\u003emod, sname, shdr-\u003esh_size,\n+\t\t\t\tarch_mod_section_prepend(info-\u003emod, i), shdr-\u003esh_addralign);\n+\t\tif (WARN_ON(!dest)) {\n+\t\t\tcodetag_free_module_sections(info-\u003emod);\n+\t\t\treturn -EINVAL;\n+\t\t}\n+\t\tif (dest == ERR_PTR(-EAGAIN))\n+\t\t\t/ Allocate the section as a regular section. /\n+\t\t\tcontinue;\n+\t\tif (IS_ERR(dest)) {\n+\t\t\tcodetag_free_module_sections(info-\u003emod);\n+\t\t\treturn PTR_ERR(dest);\n+\t\t}\n+\n+\t\tif (shdr-\u003esh_type != SHT_NOBITS)\n+\t\t\tmemcpy(dest, (void )shdr-\u003esh_addr, shdr-\u003esh_size);\n+\t\telse\n+\t\t\tmemset(dest, 0, shdr-\u003esh_size);\n+\t\tshdr-\u003esh_addr = (unsigned long)dest;\n+\t\tshdr-\u003esh_entsize = SH_ENTSIZE_STANDALONE;\n+\t}\n+\n+\treturn 0;\n+}\n+\n static struct module layout_and_allocate(struct load_info info, int flags)\n {\n \tstruct module mod;\n+\tunsigned int i;\n \tint err;\n \n \t/ Allow arches to frob section contents and sizes. /\n@@ -2967,8 +2968,13 @@ static struct module layout_and_allocate(struct load_info info, int flags)\n \tif (err \u003c 0)\n \t\treturn ERR_PTR(err);\n \n+\t/ Repurpose sh_entsize to track where each section is allocated. /\n+\tfor (i = 0; i \u003c info-\u003ehdr-\u003ee_shnum; i++)\n+\t\tinfo-\u003esechdrs[i].sh_entsize = ~0UL;\n+\n \t/ We will do a special allocation for per-cpu sections later. /\n-\tinfo-\u003esechdrs[info-\u003eindex.pcpu].sh_flags \u0026= ~(unsigned long)SHF_ALLOC;\n+\tif (info-\u003eindex.pcpu)\n+\t\tinfo-\u003esechdrs[info-\u003eindex.pcpu].sh_entsize = SH_ENTSIZE_STANDALONE;\n \n \t/\n \t * Mark relevant sections as SHF_RO_AFTER_INIT so layout_sections() can\n@@ -2977,18 +2983,21 @@ static struct module layout_and_allocate(struct load_info info, int flags)\n \t /\n \tmodule_mark_ro_after_init(info-\u003ehdr, info-\u003esechdrs, info-\u003esecstrings);\n \n-\t/\n-\t * Determine total sizes, and put offsets in sh_entsize. For now\n-\t * this is done generically; there doesn't appear to be any\n-\t * special cases for the architectures.\n-\t /\n+\t/ Allow codetag sections to be allocated separately first. /\n+\terr = allocate_codetag_sections(info);\n+\tif (err)\n+\t\treturn ERR_PTR(err);\n+\n+\t/ Determine total sizes and put offsets in sh_entsize. /\n \tlayout_sections(info-\u003emod, info);\n \tlayout_symtab(info-\u003emod, info);\n \n \t/ Allocate and move to the final place /\n \terr = move_module(info-\u003emod, info);\n-\tif (err)\n+\tif (err) {\n+\t\tcodetag_free_module_sections(info-\u003emod);\n \t\treturn ERR_PTR(err);\n+\t}\n \n \t/ Module has been copied to its final place now: return it. /\n \tmod = (void )info-\u003esechdrs[info-\u003eindex.mod].sh_addr;\ndiff --git a/kernel/module/sysfs.c b/kernel/module/sysfs.c\nindex 01c65d6088737..15c6baeb39c4c 100644\n--- a/kernel/module/sysfs.c\n+++ b/kernel/module/sysfs.c\n@@ -62,6 +62,15 @@ static void free_sect_attrs(struct module_sect_attrs sect_attrs)\n \tkfree(sect_attrs);\n }\n \n+/\n+ * .data..percpu has a separate allocation per CPU and no single\n+ * address to report.\n+ /\n+static bool sect_visible(const struct load_info info, unsigned int i)\n+{\n+\treturn !sect_empty(\u0026info-\u003esechdrs[i]) \u0026\u0026 i != info-\u003eindex.pcpu;\n+}\n+\n static int add_sect_attrs(struct module mod, const struct load_info info)\n {\n \tstruct module_sect_attrs sect_attrs;\n@@ -72,7 +81,7 @@ static int add_sect_attrs(struct module mod, const struct load_info info)\n \n \t/ Count loaded sections and allocate structures /\n \tfor (i = 0; i \u003c info-\u003ehdr-\u003ee_shnum; i++)\n-\t\tif (!sect_empty(\u0026info-\u003esechdrs[i]))\n+\t\tif (sect_visible(info, i))\n \t\t\tnloaded++;\n \tsect_attrs = kzalloc_flex(sect_attrs, attrs, nloaded);\n \tif (!sect_attrs)\n@@ -92,7 +101,7 @@ static int add_sect_attrs(struct module mod, const struct load_info info)\n \tfor (i = 0; i \u003c info-\u003ehdr-\u003ee_shnum; i++) {\n \t\tElf_Shdr sec = \u0026info-\u003esechdrs[i];\n \n-\t\tif (sect_empty(sec))\n+\t\tif (!sect_visible(info, i))\n \t\t\tcontinue;\n \t\tsysfs_bin_attr_init(sattr);\n \t\tsattr-\u003eattr.name =\n@@ -159,7 +168,7 @@ static int add_notes_attrs(struct module mod, const struct load_info info)\n \t/ Count notes sections and allocate structures. /\n \tnotes = 0;\n \tfor (i = 0; i \u003c info-\u003ehdr-\u003ee_shnum; i++)\n-\t\tif (!sect_empty(\u0026info-\u003esechdrs[i]) \u0026\u0026\n+\t\tif (sect_visible(info, i) \u0026\u0026\n \t\t info-\u003esechdrs[i].sh_type == SHT_NOTE)\n \t\t\t++notes;\n \n@@ -181,7 +190,7 @@ static int add_notes_attrs(struct module mod, const struct load_info info)\n \n \tnattr = \u0026notes_attrs-\u003eattrs[0];\n \tfor (loaded = i = 0; i \u003c info-\u003ehdr-\u003ee_shnum; ++i) {\n-\t\tif (sect_empty(\u0026info-\u003esechdrs[i]))\n+\t\tif (!sect_visible(info, i))\n \t\t\tcontinue;\n \t\tif (info-\u003esechdrs[i].sh_type == SHT_NOTE) {\n \t\t\tsysfs_bin_attr_init(nattr);\ndiff --git a/lib/codetag.c b/lib/codetag.c\nindex a9cda4c962a30..a0b600720afc1 100644\n--- a/lib/codetag.c\n+++ b/lib/codetag.c\n@@ -240,7 +240,9 @@ static int codetag_module_init(struct codetag_type cttype, struct module mod)\n \n \tif (err \u003c 0) {\n \t\tkfree(cmod);\n-\t\treturn err;\n+\t\t/ -EOPNOTSUPP means we can load the module without its tag. /\n+\t\tif (err != -EOPNOTSUPP)\n+\t\t\treturn err;\n \t}\n \n \treturn 0;\n@@ -388,7 +390,11 @@ void codetag_unload_module(struct module mod)\n \t\t\t++cttype-\u003econtent_id;\n \t\t}\n \t\tup_write(\u0026cttype-\u003emod_lock);\n-\t\tif (found \u0026\u0026 cttype-\u003edesc.free_section_mem)\n+\t\t/\n+\t\t A module whose module_load() returned -EOPNOTSUPP is not\n+\t\t * in the idr but may still hold reserved section memory.\n+\t\t /\n+\t\tif (cttype-\u003edesc.free_section_mem)\n \t\t\tcttype-\u003edesc.free_section_mem(mod, true);\n \t}\n \tmutex_unlock(\u0026codetag_lock);\ndiff --git a/mm/alloc_tag.c b/mm/alloc_tag.c\nindex b334103104779..cfa0fc84b68f9 100644\n--- a/mm/alloc_tag.c\n+++ b/mm/alloc_tag.c\n@@ -15,6 +15,7 @@\n #include \u003clinux/seq_file.h\u003e\n #include \u003clinux/string_choices.h\u003e\n #include \u003clinux/vmalloc.h\u003e\n+#include \u003clinux/workqueue.h\u003e\n #include \u003clinux/kmemleak.h\u003e\n #include \u003cuapi/linux/alloc_tag.h\u003e\n \n@@ -591,6 +592,13 @@ void pgalloc_tag_swap(struct folio new, struct folio old)\n \tput_page_tag_ref(handle_new);\n }\n \n+static void remove_allocinfo_file(struct work_struct work)\n+{\n+\tremove_proc_entry(ALLOCINFO_FILE_NAME, NULL);\n+}\n+\n+static DECLARE_WORK(remove_allocinfo_work, remove_allocinfo_file);\n+\n static void shutdown_mem_profiling(bool remove_file)\n {\n \tif (mem_alloc_profiling_enabled())\n@@ -600,7 +608,7 @@ static void shutdown_mem_profiling(bool remove_file)\n \t\treturn;\n \n \tif (remove_file)\n-\t\tremove_proc_entry(ALLOCINFO_FILE_NAME, NULL);\n+\t\tschedule_work(\u0026remove_allocinfo_work);\n \tmem_profiling_support = false;\n }\n \n@@ -804,6 +812,13 @@ static int vm_module_tags_populate(void)\n \t\t\t\t next_page, PAGE_SHIFT) \u003c 0) {\n \t\t\trelease_pages_arg arg = { .pages = next_page };\n \n+\t\t\t/\n+\t\t\t vmap_pages_range() only runs once all pages were\n+\t\t\t * allocated, and it may have installed some mappings\n+\t\t\t * before failing. Undo them.\n+\t\t\t /\n+\t\t\tif (nr == more_pages)\n+\t\t\t\tvunmap_range(phys_end, phys_end + (nr \u003c\u003c PAGE_SHIFT));\n \t\t\t/ Clean up and error out /\n \t\t\trelease_pages(arg, nr);\n \t\t\treturn -ENOMEM;\n@@ -835,6 +850,52 @@ static int vm_module_tags_populate(void)\n \treturn 0;\n }\n \n+static void release_module_tags(struct module mod, bool used)\n+{\n+\tMA_STATE(mas, \u0026mod_area_mt, module_tags.size, module_tags.size);\n+\tstruct alloc_tag start_tag;\n+\tstruct alloc_tag end_tag;\n+\tstruct module val;\n+\n+\tmas_lock(\u0026mas);\n+\tmas_for_each_rev(\u0026mas, val, 0)\n+\t\tif (val == mod)\n+\t\t\tbreak;\n+\n+\tif (!val) / module not found /\n+\t\tgoto out;\n+\n+\tif (!used)\n+\t\tgoto release_area;\n+\n+\tstart_tag = (struct alloc_tag )(module_tags.start_addr + mas.index);\n+\tend_tag = (struct alloc_tag )(module_tags.start_addr + mas.last);\n+\tif (!clean_unused_counters(start_tag, end_tag)) {\n+\t\tstruct alloc_tag tag;\n+\n+\t\tfor (tag = start_tag; tag \u003c= end_tag; tag++) {\n+\t\t\tstruct alloc_tag_counters counter;\n+\n+\t\t\tif (!tag-\u003ecounters)\n+\t\t\t\tcontinue;\n+\n+\t\t\tcounter = alloc_tag_read(tag);\n+\t\t\tpr_info(\"%s:%u module %s func:%s has %llu allocated at module unload\\n\",\n+\t\t\t\ttag-\u003ect.filename, tag-\u003ect.lineno, tag-\u003ect.modname,\n+\t\t\t\ttag-\u003ect.function, counter.bytes);\n+\t\t}\n+\t} else {\n+\t\tused = false;\n+\t}\n+release_area:\n+\tmas_store(\u0026mas, used ? \u0026unloaded_mod : NULL);\n+\tval = mas_prev_range(\u0026mas, 0);\n+\tif (val == \u0026prepend_mod)\n+\t\tmas_store(\u0026mas, NULL);\n+out:\n+\tmas_unlock(\u0026mas);\n+}\n+\n static void reserve_module_tags(struct module mod, unsigned long size,\n \t\t\t\t unsigned int prepend, unsigned long align)\n {\n@@ -901,13 +962,17 @@ static void reserve_module_tags(struct module mod, unsigned long size,\n \t\treturn ret;\n \n \tif (module_tags.size \u003c offset + size) {\n+\t\tunsigned long prev_size = module_tags.size;\n \t\tint grow_res;\n \n \t\tmodule_tags.size = offset + size;\n-\t\tif (mem_alloc_profiling_enabled() \u0026\u0026 !tags_addressable()) {\n+\t\tif (!tags_addressable()) {\n \t\t\tshutdown_mem_profiling(true);\n-\t\t\tpr_warn(\"With module %s there are too many tags to fit in %d page flag bits. Memory allocation profiling is disabled!\\n\",\n-\t\t\t\tmod-\u003ename, NR_UNUSED_PAGEFLAG_BITS);\n+\t\t\tpr_warn_once(\"With module %s there are too many tags to fit in %d page flag bits. Memory allocation profiling is disabled!\\n\",\n+\t\t\t\t mod-\u003ename, NR_UNUSED_PAGEFLAG_BITS);\n+\t\t\trelease_module_tags(mod, false);\n+\t\t\tmodule_tags.size = prev_size;\n+\t\t\treturn ERR_PTR(-EAGAIN);\n \t\t}\n \n \t\tgrow_res = vm_module_tags_populate();\n@@ -915,6 +980,8 @@ static void reserve_module_tags(struct module mod, unsigned long size,\n \t\t\tshutdown_mem_profiling(true);\n \t\t\tpr_err(\"Failed to allocate memory for allocation tags in the module %s. Memory allocation profiling is disabled!\\n\",\n \t\t\t mod-\u003ename);\n+\t\t\trelease_module_tags(mod, false);\n+\t\t\tmodule_tags.size = prev_size;\n \t\t\treturn ERR_PTR(grow_res);\n \t\t}\n \t}\n@@ -922,52 +989,6 @@ static void reserve_module_tags(struct module mod, unsigned long size,\n \treturn (struct alloc_tag )(module_tags.start_addr + offset);\n }\n \n-static void release_module_tags(struct module mod, bool used)\n-{\n-\tMA_STATE(mas, \u0026mod_area_mt, module_tags.size, module_tags.size);\n-\tstruct alloc_tag start_tag;\n-\tstruct alloc_tag end_tag;\n-\tstruct module val;\n-\n-\tmas_lock(\u0026mas);\n-\tmas_for_each_rev(\u0026mas, val, 0)\n-\t\tif (val == mod)\n-\t\t\tbreak;\n-\n-\tif (!val) / module not found /\n-\t\tgoto out;\n-\n-\tif (!used)\n-\t\tgoto release_area;\n-\n-\tstart_tag = (struct alloc_tag )(module_tags.start_addr + mas.index);\n-\tend_tag = (struct alloc_tag )(module_tags.start_addr + mas.last);\n-\tif (!clean_unused_counters(start_tag, end_tag)) {\n-\t\tstruct alloc_tag tag;\n-\n-\t\tfor (tag = start_tag; tag \u003c= end_tag; tag++) {\n-\t\t\tstruct alloc_tag_counters counter;\n-\n-\t\t\tif (!tag-\u003ecounters)\n-\t\t\t\tcontinue;\n-\n-\t\t\tcounter = alloc_tag_read(tag);\n-\t\t\tpr_info(\"%s:%u module %s func:%s has %llu allocated at module unload\\n\",\n-\t\t\t\ttag-\u003ect.filename, tag-\u003ect.lineno, tag-\u003ect.modname,\n-\t\t\t\ttag-\u003ect.function, counter.bytes);\n-\t\t}\n-\t} else {\n-\t\tused = false;\n-\t}\n-release_area:\n-\tmas_store(\u0026mas, used ? \u0026unloaded_mod : NULL);\n-\tval = mas_prev_range(\u0026mas, 0);\n-\tif (val == \u0026prepend_mod)\n-\t\tmas_store(\u0026mas, NULL);\n-out:\n-\tmas_unlock(\u0026mas);\n-}\n-\n static int load_module(struct module mod, struct codetag start, struct codetag stop)\n {\n \t/ Allocate module alloc_tag percpu counters /\n@@ -975,6 +996,10 @@ static int load_module(struct module mod, struct codetag start, struct codetag\n \tstruct alloc_tag stop_tag;\n \tstruct alloc_tag tag;\n \n+\t/ Profiling disabled: load the module without its tags. /\n+\tif (!mem_profiling_support)\n+\t\treturn -EOPNOTSUPP;\n+\n \t/ percpu counters for core allocations are already statically allocated */\n \tif (!mod)\n \t\treturn 0;\n@@ -1341,16 +1366,10 @@ static int __init alloc_tag_init(void)\n \t\treturn 0;\n \t}\n \n-\tif (!proc_create(ALLOCINFO_FILE_NAME, 0400, NULL, \u0026allocinfo_proc_ops)) {\n-\t\tpr_err(\"Failed to create %s file\\n\", ALLOCINFO_FILE_NAME);\n-\t\tshutdown_mem_profiling(false);\n-\t\treturn -ENOMEM;\n-\t}\n-\n \tres = alloc_mod_tags_mem();\n \tif (res) {\n \t\tpr_err(\"Failed to reserve address space for module tags, errno = %d\\n\", res);\n-\t\tshutdown_mem_profiling(true);\n+\t\tshutdown_mem_profiling(false);\n \t\treturn res;\n \t}\n \n@@ -1358,10 +1377,16 @@ static int __init alloc_tag_init(void)\n \tif (IS_ERR(alloc_tag_cttype)) {\n \t\tpr_err(\"Allocation tags registration failed, errno = %pe\\n\", alloc_tag_cttype);\n \t\tfree_mod_tags_mem();\n-\t\tshutdown_mem_profiling(true);\n+\t\tshutdown_mem_profiling(false);\n \t\treturn PTR_ERR(alloc_tag_cttype);\n \t}\n \n+\tif (!proc_create(ALLOCINFO_FILE_NAME, 0400, NULL, \u0026allocinfo_proc_ops)) {\n+\t\tpr_err(\"Failed to create %s file\\n\", ALLOCINFO_FILE_NAME);\n+\t\tshutdown_mem_profiling(false);\n+\t\treturn -ENOMEM;\n+\t}\n+\n \treturn 0;\n }\n module_init(alloc_tag_init);\n" }
2/1	2026/09/15 07:27	agent	patch-evaluator	11m Model: core Args: null Results: { "EnableConfigs": [ "MODULES", "MEM_ALLOC_PROFILING", "SYSFS", "KALLSYMS", "PROC_FS" ], "FocusSymbols": [ "allocate_codetag_sections", "layout_and_allocate", "move_module", "apply_relocations", "layout_symtab", "add_kallsyms", "add_sect_attrs", "add_notes_attrs", "codetag_alloc_module_section", "codetag_free_module_sections", "codetag_load_module", "codetag_unload_module", "reserve_module_tags", "release_module_tags", "vm_module_tags_populate", "shutdown_mem_profiling" ], "Reasoning": "The patch series refactors core module loading, section layout handling (introducing SH_ENTSIZE_STANDALONE for per-CPU and codetag sections), and memory allocation profiling error handling and cleanup paths (mm/alloc_tag.c and lib/codetag.c). It modifies module allocation and relocation flows, adds error rollback in vm_module_tags_populate and reserve_module_tags, and alters module loading behaviors when codetag capacity is exhausted. These changes are reachable in standard virtualized environments via module loader syscalls (init_module, finit_module) and procfs/sysfs interactions.", "WorthFuzzing": true } Instruction: You are an expert Linux kernel maintainer and security engineer. Your job is to review a provided patch series and evaluate whether it warrants fuzzing with syzkaller. IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in your workspace. Do NOT rely on internal assumptions. You must actively use your code access tools to inspect the actual source code, callers, and surrounding context. ================================================================================ 1. CORE TRIAGE PHILOSOPHY ================================================================================ The goal of patch fuzzing is to discover crashes, regressions, exposed latent bugs, and newly triggered assertions introduced by the patch series. - REACHABILITY IS THE PRIMARY GATE: Fuzzing can only discover bugs in code that can actually execute in standard virtualized environments (GCE or QEMU, utilizing software-emulated devices like USB gadgets, netdev, tun/tap). If the modified code is structurally unreachable (see Section 2), it MUST NOT be fuzzed, regardless of whether it adds assertions or complex logic. - DO NOT BLINDLY TRUST "NO FUNCTIONAL CHANGE" (NFCI) OR "REFACTORING" CLAIMS: Patch authors routinely label changes as "cleanups", "refactorings", or state "No functional change intended". Do NOT take these claims at face value. Code refactorings that rearrange logic, introduce helper functions, or alter state management in core subsystems frequently introduce subtle semantic shifts or uncover latent kernel bugs. If reachable executable code is modified or refactored, it MUST be fuzzed. - NEW OR MODIFIED ASSERTIONS IN REACHABLE CODE MUST BE FUZZED: When a patch introduces or modifies runtime checks or assertions (e.g., WARN_ON, VM_WARN_ON, BUG_ON, lockdep_assert) in reachable code paths, it enforces new or stricter invariants. Even if the author believes the invariant always holds, fuzzing is essential to verify whether an unusual sequence of operations can violate it. ================================================================================ 2. WHEN TO RETURN WorthFuzzing=false (NEGATIVE CRITERIA) ================================================================================ Return WorthFuzzing=false ONLY IF all modified code falls strictly into one or more of these categories: - Non-kernel and non-executable changes: * Modifications to Documentation/, comments, or spelling fixes. * User-space directories, self-tests, samples, or scripts (e.g., tools/, samples/, scripts/, usr/) that do not affect the compiled kernel image (vmlinux) or kernel modules. * Purely decorative logging (e.g., message strings in pr_err, printk, dev_info) or tracepoints that do not alter control flow or data structures. * Build system or Kconfig changes that do not alter compiled C logic. - Structurally unreachable hardware: * Vendor-specific PCIe switches, SmartNICs, or GPU drivers (e.g., mlxsw, pds_core, qed, ionic, amdgpu) requiring physical ASIC/PCIe cards not emulated in standard QEMU. - Unreachable execution paths: * Driver teardown callbacks (.remove, .shutdown, pci_unregister_driver) executed only during physical PCI hot-unplug or manual sysfs driver unbinding. * Code paths exclusive to architectures other than the target architecture. ================================================================================ 3. WHEN TO RETURN WorthFuzzing=true (POSITIVE CRITERIA) ================================================================================ Return WorthFuzzing=true whenever the patch touches reachable executable code, including: - Core Subsystems: * Any logic modifications in memory management (mm/), synchronization/locking (kernel/locking/), BPF, scheduler, core networking, VFS, or syscall handling. - Refactorings and Code Cleanups: * Any restructuring of reachable data structures, helper abstractions, or algorithm flows. - Runtime Assertions and Defensive Checks: * Any introduction or alteration of assertions (WARN_ON, VM_WARN_ON, BUG_ON, etc.) in reachable paths. - Reachable Drivers and Protocols: Drivers accessible via virtual buses (virtio, USB gadget, loopback, netlink, binder, sockets, etc.). ================================================================================ 4. EXTRACTING FocusSymbols (PREVENTING DILUTION) ================================================================================ When WorthFuzzing=true, you must extract specific kernel functions into FocusSymbols to guide the fuzzer: - AVOID UBIQUITOUS LIFECYCLE HOT-PATHS: Do NOT list generic, ubiquitous functions called by almost every program in the corpus (including, but not limited to: general memory allocators and deallocators, page fault and trap handlers, or core synchronization primitives; this is not an exhaustive list). Listing ubiquitous functions causes the fuzzer to classify thousands of unrelated tests as "focused", which severely dilutes fuzzing effort away from the actual changes. - TARGET SPECIFIC FEATURE LOGIC AND ENTRYPOINTS: List functions that specifically implement the logic being added or altered, or direct API entrypoints for the subsystem feature under review. - HANDLING STATIC INLINE FUNCTIONS IN HEADERS (.h): Compiler-inlined static functions (such as static inlines in mm/.h or include/linux/.h) lack distinct symbol addresses in vmlinux and cannot be targeted directly by symbol coverage filters. If the changes are primarily in static inline helpers, identify non-static, feature-specific caller functions in .c files that exercise them (avoiding ubiquitous lifecycle wrappers). ================================================================================ 5. IDENTIFYING EnableConfigs ================================================================================ Identify any specific CONFIG_ options required to properly compile and reach the modified code: - Inspect Kconfig files and #ifdef guards; do not make assumptions. - Check "depends on" lines in Kconfig to include any non-standard parent subsystem configs needed. - Strip any 'CONFIG_' prefix (e.g., return "NET_IPV4" instead of "CONFIG_NET_IPV4"). Prefer calling several tools at the same time to save round-trips. Use set-results tool to provide results of the analysis. It must be called exactly once before the final reply. Ignore results of this tool. Prompt: Target architecture: amd64 For your convenience, here is the diff of the changes: commit 24d9f5e60beaa38a9de84cd878030514129be9c5 Author: syz-cluster <triage@syzkaller.com> Date: Tue Sep 15 07:27:34 2026 +0000 syz-cluster: applied patch under review diff --git a/include/linux/module.h b/include/linux/module.h index 96cc98568eea5..0c6f32ddcbf2d 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -325,6 +325,8 @@ enum mod_mem_type { MOD_INIT_RODATA, MOD_MEM_NUM_TYPES, + + MOD_STANDALONE = -2, MOD_INVALID = -1, }; diff --git a/kernel/module/internal.h b/kernel/module/internal.h index 061161cc79d90..4c738074a27b8 100644 --- a/kernel/module/internal.h +++ b/kernel/module/internal.h @@ -29,6 +29,14 @@ #define SH_ENTSIZE_TYPE_MASK ((1UL << SH_ENTSIZE_TYPE_BITS) - 1) #define SH_ENTSIZE_OFFSET_MASK ((1UL << (BITS_PER_LONG - SH_ENTSIZE_TYPE_BITS)) - 1) +/* + * Marker for sections with a separate allocation, which are not placed + * into mod->mem[]. + / +#define SH_ENTSIZE_STANDALONE \ + (((unsigned long)MOD_STANDALONE & SH_ENTSIZE_TYPE_MASK) \ + << SH_ENTSIZE_TYPE_SHIFT) + / Maximum number of characters written by module_flags() / #define MODULE_FLAGS_BUF_SIZE (TAINT_FLAGS_COUNT + 4) diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c index f23126d804b25..0dca6d40160e5 100644 --- a/kernel/module/kallsyms.c +++ b/kernel/module/kallsyms.c @@ -76,7 +76,7 @@ static char elf_type(const Elf_Sym sym, const struct load_info info) } static bool is_core_symbol(const Elf_Sym src, const Elf_Shdr sechdrs, - unsigned int shnum, unsigned int pcpundx) + unsigned int shnum) { const Elf_Shdr sec; enum mod_mem_type type; @@ -86,11 +86,6 @@ static bool is_core_symbol(const Elf_Sym src, const Elf_Shdr sechdrs, !src->st_name) return false; -#ifdef CONFIG_KALLSYMS_ALL - if (src->st_shndx == pcpundx) - return true; -#endif - sec = sechdrs + src->st_shndx; type = sec->sh_entsize >> SH_ENTSIZE_TYPE_SHIFT; if (!(sec->sh_flags & SHF_ALLOC) @@ -131,8 +126,7 @@ void layout_symtab(struct module mod, struct load_info info) /* Compute total space required for the core symbols' strtab. / for (ndst = i = 0; i < nsrc; i++) { if (i == 0 \|\| is_livepatch_module(mod) \|\| - is_core_symbol(src + i, info->sechdrs, info->hdr->e_shnum, - info->index.pcpu)) { + is_core_symbol(src + i, info->sechdrs, info->hdr->e_shnum)) { strtab_size += strlen(&info->strtab[src[i].st_name]) + 1; ndst++; } @@ -199,8 +193,7 @@ void add_kallsyms(struct module mod, const struct load_info info) for (ndst = i = 0; i < kallsyms->num_symtab; i++) { kallsyms->typetab[i] = elf_type(src + i, info); if (i == 0 \|\| is_livepatch_module(mod) \|\| - is_core_symbol(src + i, info->sechdrs, info->hdr->e_shnum, - info->index.pcpu)) { + is_core_symbol(src + i, info->sechdrs, info->hdr->e_shnum)) { ssize_t ret; mod->core_kallsyms.typetab[ndst] = diff --git a/kernel/module/main.c b/kernel/module/main.c index c1b34dc1e89ac..b7ebcc40bddab 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -1619,12 +1619,13 @@ static int apply_relocations(struct module mod, const struct load_info info) / * Don't bother with non-allocated sections. - * An exception is the percpu section, which has separate allocations - * for individual CPUs. We relocate the percpu section in the initial - * ELF template and subsequently copy it to the per-CPU destinations. + * + * Note that .data..percpu has separate allocations for + * individual CPUs. We relocate the section in the + * initial ELF template and subsequently copy it to the + * per-CPU destinations. / - if (!(info->sechdrs[infosec].sh_flags & SHF_ALLOC) && - (!infosec \|\| infosec != info->index.pcpu)) + if (!(info->sechdrs[infosec].sh_flags & SHF_ALLOC)) continue; if (info->sechdrs[i].sh_flags & SHF_RELA_LIVEPATCH) @@ -1715,27 +1716,13 @@ static void __layout_sections(struct module mod, struct load_info info, bool i if ((s->sh_flags & masks[m][0]) != masks[m][0] \|\| (s->sh_flags & masks[m][1]) - \|\| s->sh_entsize != ~0UL + \|\| s->sh_entsize != ~0UL / offset or standalone / \|\| is_init != module_init_layout_section(sname)) continue; if (WARN_ON_ONCE(type == MOD_INVALID)) continue; - / - * Do not allocate codetag memory as we load it into - * preallocated contiguous memory. - / - if (codetag_needs_module_section(mod, sname, s->sh_size)) { - / - * s->sh_entsize won't be used but populate the - * type field to avoid confusion. - / - s->sh_entsize = ((unsigned long)(type) & SH_ENTSIZE_TYPE_MASK) - << SH_ENTSIZE_TYPE_SHIFT; - continue; - } - s->sh_entsize = module_get_offset_and_type(mod, type, s, i); pr_debug("\t%s\n", sname); } @@ -1745,16 +1732,10 @@ static void __layout_sections(struct module mod, struct load_info info, bool i / * Lay out the SHF_ALLOC sections in a way not dissimilar to how ld * might -- code, read-only data, read-write data, small data. Tally - * sizes, and place the offsets into sh_entsize fields: high bit means it - * belongs in init. + * sizes, and place the offsets into sh_entsize fields. / static void layout_sections(struct module mod, struct load_info info) { - unsigned int i; - - for (i = 0; i < info->hdr->e_shnum; i++) - info->sechdrs[i].sh_entsize = ~0UL; - pr_debug("Core section allocation order for %s:\n", mod->name); __layout_sections(mod, info, false); @@ -2800,7 +2781,6 @@ static int move_module(struct module mod, struct load_info info) { int i, ret; enum mod_mem_type t = MOD_MEM_NUM_TYPES; - bool codetag_section_found = false; for_each_mod_mem_type(type) { if (!mod->mem[type].size) { @@ -2820,34 +2800,13 @@ static int move_module(struct module mod, struct load_info info) for (i = 0; i < info->hdr->e_shnum; i++) { void dest; Elf_Shdr shdr = &info->sechdrs[i]; - const char sname; - if (!(shdr->sh_flags & SHF_ALLOC)) + if (!(shdr->sh_flags & SHF_ALLOC) + \|\| shdr->sh_entsize == SH_ENTSIZE_STANDALONE) continue; - sname = info->secstrings + shdr->sh_name; - /* - * Load codetag sections separately as they might still be used - * after module unload. - / - if (codetag_needs_module_section(mod, sname, shdr->sh_size)) { - dest = codetag_alloc_module_section(mod, sname, shdr->sh_size, - arch_mod_section_prepend(mod, i), shdr->sh_addralign); - if (WARN_ON(!dest)) { - ret = -EINVAL; - goto out_err; - } - if (IS_ERR(dest)) { - ret = PTR_ERR(dest); - goto out_err; - } - codetag_section_found = true; - } else { - enum mod_mem_type type = shdr->sh_entsize >> SH_ENTSIZE_TYPE_SHIFT; - unsigned long offset = shdr->sh_entsize & SH_ENTSIZE_OFFSET_MASK; - - dest = mod->mem[type].base + offset; - } + dest = mod->mem[shdr->sh_entsize >> SH_ENTSIZE_TYPE_SHIFT].base + + (shdr->sh_entsize & SH_ENTSIZE_OFFSET_MASK); if (shdr->sh_type != SHT_NOBITS) { / @@ -2879,8 +2838,6 @@ static int move_module(struct module mod, struct load_info info) module_memory_restore_rox(mod); while (t--) module_memory_free(mod, t); - if (codetag_section_found) - codetag_free_module_sections(mod); return ret; } @@ -2951,9 +2908,53 @@ static bool blacklisted(const char module_name) } core_param(module_blacklist, module_blacklist, charp, 0400); +/ + * Allocate codetag sections separately. They are loaded into preallocated + * contiguous memory because they may still be used after the module is + * unloaded. + * + * If the separate allocation overflows, allocate the section normally + * so that the module can still be loaded. + / +static int allocate_codetag_sections(struct load_info info) +{ + for (unsigned int i = 1; i < info->hdr->e_shnum; i++) { + Elf_Shdr shdr = &info->sechdrs[i]; + const char sname = info->secstrings + shdr->sh_name; + void dest; + + if (!codetag_needs_module_section(info->mod, sname, shdr->sh_size)) + continue; + + dest = codetag_alloc_module_section(info->mod, sname, shdr->sh_size, + arch_mod_section_prepend(info->mod, i), shdr->sh_addralign); + if (WARN_ON(!dest)) { + codetag_free_module_sections(info->mod); + return -EINVAL; + } + if (dest == ERR_PTR(-EAGAIN)) + / Allocate the section as a regular section. / + continue; + if (IS_ERR(dest)) { + codetag_free_module_sections(info->mod); + return PTR_ERR(dest); + } + + if (shdr->sh_type != SHT_NOBITS) + memcpy(dest, (void )shdr->sh_addr, shdr->sh_size); + else + memset(dest, 0, shdr->sh_size); + shdr->sh_addr = (unsigned long)dest; + shdr->sh_entsize = SH_ENTSIZE_STANDALONE; + } + + return 0; +} + static struct module layout_and_allocate(struct load_info info, int flags) { struct module mod; + unsigned int i; int err; / Allow arches to frob section contents and sizes. / @@ -2967,8 +2968,13 @@ static struct module layout_and_allocate(struct load_info info, int flags) if (err < 0) return ERR_PTR(err); + / Repurpose sh_entsize to track where each section is allocated. / + for (i = 0; i < info->hdr->e_shnum; i++) + info->sechdrs[i].sh_entsize = ~0UL; + / We will do a special allocation for per-cpu sections later. / - info->sechdrs[info->index.pcpu].sh_flags &= ~(unsigned long)SHF_ALLOC; + if (info->index.pcpu) + info->sechdrs[info->index.pcpu].sh_entsize = SH_ENTSIZE_STANDALONE; / * Mark relevant sections as SHF_RO_AFTER_INIT so layout_sections() can @@ -2977,18 +2983,21 @@ static struct module layout_and_allocate(struct load_info info, int flags) / module_mark_ro_after_init(info->hdr, info->sechdrs, info->secstrings); - / - * Determine total sizes, and put offsets in sh_entsize. For now - * this is done generically; there doesn't appear to be any - * special cases for the architectures. - / + / Allow codetag sections to be allocated separately first. / + err = allocate_codetag_sections(info); + if (err) + return ERR_PTR(err); + + / Determine total sizes and put offsets in sh_entsize. / layout_sections(info->mod, info); layout_symtab(info->mod, info); / Allocate and move to the final place / err = move_module(info->mod, info); - if (err) + if (err) { + codetag_free_module_sections(info->mod); return ERR_PTR(err); + } / Module has been copied to its final place now: return it. / mod = (void )info->sechdrs[info->index.mod].sh_addr; diff --git a/kernel/module/sysfs.c b/kernel/module/sysfs.c index 01c65d6088737..15c6baeb39c4c 100644 --- a/kernel/module/sysfs.c +++ b/kernel/module/sysfs.c @@ -62,6 +62,15 @@ static void free_sect_attrs(struct module_sect_attrs sect_attrs) kfree(sect_attrs); } +/ + * .data..percpu has a separate allocation per CPU and no single + * address to report. + / +static bool sect_visible(const struct load_info info, unsigned int i) +{ + return !sect_empty(&info->sechdrs[i]) && i != info->index.pcpu; +} + static int add_sect_attrs(struct module mod, const struct load_info info) { struct module_sect_attrs sect_attrs; @@ -72,7 +81,7 @@ static int add_sect_attrs(struct module mod, const struct load_info info) / Count loaded sections and allocate structures / for (i = 0; i < info->hdr->e_shnum; i++) - if (!sect_empty(&info->sechdrs[i])) + if (sect_visible(info, i)) nloaded++; sect_attrs = kzalloc_flex(sect_attrs, attrs, nloaded); if (!sect_attrs) @@ -92,7 +101,7 @@ static int add_sect_attrs(struct module mod, const struct load_info info) for (i = 0; i < info->hdr->e_shnum; i++) { Elf_Shdr sec = &info->sechdrs[i]; - if (sect_empty(sec)) + if (!sect_visible(info, i)) continue; sysfs_bin_attr_init(sattr); sattr->attr.name = @@ -159,7 +168,7 @@ static int add_notes_attrs(struct module mod, const struct load_info info) / Count notes sections and allocate structures. / notes = 0; for (i = 0; i < info->hdr->e_shnum; i++) - if (!sect_empty(&info->sechdrs[i]) && + if (sect_visible(info, i) && info->sechdrs[i].sh_type == SHT_NOTE) ++notes; @@ -181,7 +190,7 @@ static int add_notes_attrs(struct module mod, const struct load_info info) nattr = &notes_attrs->attrs[0]; for (loaded = i = 0; i < info->hdr->e_shnum; ++i) { - if (sect_empty(&info->sechdrs[i])) + if (!sect_visible(info, i)) continue; if (info->sechdrs[i].sh_type == SHT_NOTE) { sysfs_bin_attr_init(nattr); diff --git a/lib/codetag.c b/lib/codetag.c index a9cda4c962a30..a0b600720afc1 100644 --- a/lib/codetag.c +++ b/lib/codetag.c @@ -240,7 +240,9 @@ static int codetag_module_init(struct codetag_type cttype, struct module mod) if (err < 0) { kfree(cmod); - return err; + / -EOPNOTSUPP means we can load the module without its tag. / + if (err != -EOPNOTSUPP) + return err; } return 0; @@ -388,7 +390,11 @@ void codetag_unload_module(struct module mod) ++cttype->content_id; } up_write(&cttype->mod_lock); - if (found && cttype->desc.free_section_mem) + /* + * A module whose module_load() returned -EOPNOTSUPP is not + * in the idr but may still hold reserved section memory. + / + if (cttype->desc.free_section_mem) cttype->desc.free_section_mem(mod, true); } mutex_unlock(&codetag_lock); diff --git a/mm/alloc_tag.c b/mm/alloc_tag.c index b334103104779..cfa0fc84b68f9 100644 --- a/mm/alloc_tag.c +++ b/mm/alloc_tag.c @@ -15,6 +15,7 @@ #include <linux/seq_file.h> #include <linux/string_choices.h> #include <linux/vmalloc.h> +#include <linux/workqueue.h> #include <linux/kmemleak.h> #include <uapi/linux/alloc_tag.h> @@ -591,6 +592,13 @@ void pgalloc_tag_swap(struct folio new, struct folio old) put_page_tag_ref(handle_new); } +static void remove_allocinfo_file(struct work_struct work) +{ + remove_proc_entry(ALLOCINFO_FILE_NAME, NULL); +} + +static DECLARE_WORK(remove_allocinfo_work, remove_allocinfo_file); + static void shutdown_mem_profiling(bool remove_file) { if (mem_alloc_profiling_enabled()) @@ -600,7 +608,7 @@ static void shutdown_mem_profiling(bool remove_file) return; if (remove_file) - remove_proc_entry(ALLOCINFO_FILE_NAME, NULL); + schedule_work(&remove_allocinfo_work); mem_profiling_support = false; } @@ -804,6 +812,13 @@ static int vm_module_tags_populate(void) next_page, PAGE_SHIFT) < 0) { release_pages_arg arg = { .pages = next_page }; + /* + * vmap_pages_range() only runs once all pages were + * allocated, and it may have installed some mappings + * before failing. Undo them. + / + if (nr == more_pages) + vunmap_range(phys_end, phys_end + (nr << PAGE_SHIFT)); / Clean up and error out / release_pages(arg, nr); return -ENOMEM; @@ -835,6 +850,52 @@ static int vm_module_tags_populate(void) return 0; } +static void release_module_tags(struct module mod, bool used) +{ + MA_STATE(mas, &mod_area_mt, module_tags.size, module_tags.size); + struct alloc_tag start_tag; + struct alloc_tag end_tag; + struct module val; + + mas_lock(&mas); + mas_for_each_rev(&mas, val, 0) + if (val == mod) + break; + + if (!val) / module not found / + goto out; + + if (!used) + goto release_area; + + start_tag = (struct alloc_tag )(module_tags.start_addr + mas.index); + end_tag = (struct alloc_tag )(module_tags.start_addr + mas.last); + if (!clean_unused_counters(start_tag, end_tag)) { + struct alloc_tag tag; + + for (tag = start_tag; tag <= end_tag; tag++) { + struct alloc_tag_counters counter; + + if (!tag->counters) + continue; + + counter = alloc_tag_read(tag); + pr_info("%s:%u module %s func:%s has %llu allocated at module unload\n", + tag->ct.filename, tag->ct.lineno, tag->ct.modname, + tag->ct.function, counter.bytes); + } + } else { + used = false; + } +release_area: + mas_store(&mas, used ? &unloaded_mod : NULL); + val = mas_prev_range(&mas, 0); + if (val == &prepend_mod) + mas_store(&mas, NULL); +out: + mas_unlock(&mas); +} + static void reserve_module_tags(struct module mod, unsigned long size, unsigned int prepend, unsigned long align) { @@ -901,13 +962,17 @@ static void reserve_module_tags(struct module mod, unsigned long size, return ret; if (module_tags.size < offset + size) { + unsigned long prev_size = module_tags.size; int grow_res; module_tags.size = offset + size; - if (mem_alloc_profiling_enabled() && !tags_addressable()) { + if (!tags_addressable()) { shutdown_mem_profiling(true); - pr_warn("With module %s there are too many tags to fit in %d page flag bits. Memory allocation profiling is disabled!\n", - mod->name, NR_UNUSED_PAGEFLAG_BITS); + pr_warn_once("With module %s there are too many tags to fit in %d page flag bits. Memory allocation profiling is disabled!\n", + mod->name, NR_UNUSED_PAGEFLAG_BITS); + release_module_tags(mod, false); + module_tags.size = prev_size; + return ERR_PTR(-EAGAIN); } grow_res = vm_module_tags_populate(); @@ -915,6 +980,8 @@ static void reserve_module_tags(struct module mod, unsigned long size, shutdown_mem_profiling(true); pr_err("Failed to allocate memory for allocation tags in the module %s. Memory allocation profiling is disabled!\n", mod->name); + release_module_tags(mod, false); + module_tags.size = prev_size; return ERR_PTR(grow_res); } } @@ -922,52 +989,6 @@ static void reserve_module_tags(struct module mod, unsigned long size, return (struct alloc_tag )(module_tags.start_addr + offset); } -static void release_module_tags(struct module mod, bool used) -{ - MA_STATE(mas, &mod_area_mt, module_tags.size, module_tags.size); - struct alloc_tag start_tag; - struct alloc_tag end_tag; - struct module val; - - mas_lock(&mas); - mas_for_each_rev(&mas, val, 0) - if (val == mod) - break; - - if (!val) / module not found / - goto out; - - if (!used) - goto release_area; - - start_tag = (struct alloc_tag )(module_tags.start_addr + mas.index); - end_tag = (struct alloc_tag )(module_tags.start_addr + mas.last); - if (!clean_unused_counters(start_tag, end_tag)) { - struct alloc_tag tag; - - for (tag = start_tag; tag <= end_tag; tag++) { - struct alloc_tag_counters counter; - - if (!tag->counters) - continue; - - counter = alloc_tag_read(tag); - pr_info("%s:%u module %s func:%s has %llu allocated at module unload\n", - tag->ct.filename, tag->ct.lineno, tag->ct.modname, - tag->ct.function, counter.bytes); - } - } else { - used = false; - } -release_area: - mas_store(&mas, used ? &unloaded_mod : NULL); - val = mas_prev_range(&mas, 0); - if (val == &prepend_mod) - mas_store(&mas, NULL); -out: - mas_unlock(&mas); -} - static int load_module(struct module mod, struct codetag start, struct codetag stop) { / Allocate module alloc_tag percpu counters / @@ -975,6 +996,10 @@ static int load_module(struct module mod, struct codetag start, struct codetag struct alloc_tag stop_tag; struct alloc_tag tag; + / Profiling disabled: load the module without its tags. / + if (!mem_profiling_support) + return -EOPNOTSUPP; + / percpu counters for core allocations are already statically allocated */ if (!mod) return 0; @@ -1341,16 +1366,10 @@ static int __init alloc_tag_init(void) return 0; } - if (!proc_create(ALLOCINFO_FILE_NAME, 0400, NULL, &allocinfo_proc_ops)) { - pr_err("Failed to create %s file\n", ALLOCINFO_FILE_NAME); - shutdown_mem_profiling(false); - return -ENOMEM; - } - res = alloc_mod_tags_mem(); if (res) { pr_err("Failed to reserve address space for module tags, errno = %d\n", res); - shutdown_mem_profiling(true); + shutdown_mem_profiling(false); return res; } @@ -1358,10 +1377,16 @@ static int __init alloc_tag_init(void) if (IS_ERR(alloc_tag_cttype)) { pr_err("Allocation tags registration failed, errno = %pe\n", alloc_tag_cttype); free_mod_tags_mem(); - shutdown_mem_profiling(true); + shutdown_mem_profiling(false); return PTR_ERR(alloc_tag_cttype); } + if (!proc_create(ALLOCINFO_FILE_NAME, 0400, NULL, &allocinfo_proc_ops)) { + pr_err("Failed to create %s file\n", ALLOCINFO_FILE_NAME); + shutdown_mem_profiling(false); + return -ENOMEM; + } + return 0; } module_init(alloc_tag_init);
3/2	2026/09/15 07:27	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 10618 output: 29 thoughts: 843 Thoughts: Kernel Fuzzing Patch Evaluation Okay, let's dive into this patch series. My immediate goal is to determine if this modification warrants fuzzing attention with syzkaller. I'm going to start by confirming that the request is safe; it seems to be centered around kernel fuzzing triage, identifying relevant symbols and kernel configurations. So, no immediate red flags, it's just standard developer QA, which is good. Now, let's get into the code. The patch has several touchpoints: `include/linux/module.h`, `kernel/module/internal.h`, `kernel/module/kallsyms.c`, `kernel/module/main.c`, `kernel/module/sysfs.c`, `lib/codetag.c`, and `mm/alloc_tag.c`. My initial scan shows additions, removals, and modifications across a range of module handling and memory allocation functions. It seems like it is a good chunk of changes. Specifically, I see a new `MOD_STANDALONE` enum, changes related to codetag handling and section allocation in the module loading process, including new `allocate_codetag_sections`. There are some removals of checks related to pcpundx in `is_core_symbol` and `sect_empty` checks. This signals important changes in how the kernel handles module metadata and potentially influences memory layout. There is also significant refactoring in `alloc_tag.c`, which makes me immediately pay attention. It touches upon memory profiling and allocation tagging, and those modifications tend to be interesting from a fuzzing perspective, especially around error handling and resource exhaustion. To get a better contextual understanding, I'll need to use tools like `grepper` and/or `read-file` to check the context involved. I'll need to figure out which configurations are affected and what the impact is on code paths that are reachable during fuzzing. The goal here is to determine whether these changes introduce new codepaths, change existing ones significantly, or touch sensitive areas like memory management. I will also be on the lookout for potential new error conditions that might be reached.
4/2	2026/09/15 07:27	tool	grepper	0m Args: { "Expression": "MEM_ALLOC_PROFILING", "PathPrefix": "mm/" } Results: { "Output": "mm/Kconfig.debug=311=config PER_VMA_LOCK_STATS\n--\nmm/Kconfig.debug-323-\nmm/Kconfig.debug:324:config MEM_ALLOC_PROFILING\nmm/Kconfig.debug-325-\tbool \"Enable memory allocation profiling\"\n--\nmm/Kconfig.debug-336-\nmm/Kconfig.debug:337:config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT\nmm/Kconfig.debug-338-\tbool \"Enable memory allocation profiling by default\"\nmm/Kconfig.debug-339-\tdefault y\nmm/Kconfig.debug:340:\tdepends on MEM_ALLOC_PROFILING\nmm/Kconfig.debug-341-\nmm/Kconfig.debug:342:config MEM_ALLOC_PROFILING_DEBUG\nmm/Kconfig.debug-343-\tbool \"Memory allocation profiler debugging\"\nmm/Kconfig.debug-344-\tdefault n\nmm/Kconfig.debug:345:\tdepends on MEM_ALLOC_PROFILING\nmm/Kconfig.debug:346:\tselect MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT\nmm/Kconfig.debug-347-\thelp\n--\nmm/Makefile=149=obj-$(CONFIG_LAZY_MMU_MODE_KUNIT_TEST) += tests/lazy_mmu_mode_kunit.o\nmm/Makefile:150:obj-$(CONFIG_MEM_ALLOC_PROFILING) += alloc_tag.o\n--\nmm/alloc_tag.c-29-\nmm/alloc_tag.c:30:#ifdef CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT\nmm/alloc_tag.c-31-static bool mem_profiling_support = true;\n--\nmm/alloc_tag.c=49=EXPORT_SYMBOL(_shared_alloc_tag);\n--\nmm/alloc_tag.c-51-\nmm/alloc_tag.c:52:DEFINE_STATIC_KEY_MAYBE(CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT,\nmm/alloc_tag.c-53-\t\t\tmem_alloc_profiling_key);\n--\nmm/alloc_tag.c=1139=static __init bool need_page_alloc_tagging(void)\n--\nmm/alloc_tag.c-1146-\nmm/alloc_tag.c:1147:#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG\nmm/alloc_tag.c-1148-/\n--\nmm/alloc_tag.c=1225=static void __init clear_early_alloc_pfn_tag_refs(void)\n--\nmm/alloc_tag.c-1278-}\nmm/alloc_tag.c:1279:#else / !CONFIG_MEM_ALLOC_PROFILING_DEBUG /\nmm/alloc_tag.c-1280-static inline void __init clear_early_alloc_pfn_tag_refs(void) {}\nmm/alloc_tag.c:1281:#endif / CONFIG_MEM_ALLOC_PROFILING_DEBUG /\nmm/alloc_tag.c-1282-\n--\nmm/alloc_tag.c=1300=static int proc_mem_profiling_handler(const struct ctl_table table, int write,\n--\nmm/alloc_tag.c-1311-\nmm/alloc_tag.c:1312:#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG\nmm/alloc_tag.c-1313-\t\t/* User can't toggle profiling while debugging /\n--\nmm/page_alloc.c=1220=static void clear_highpages_kasan_tagged(struct page page, int numpages)\n--\nmm/page_alloc.c-1234-\nmm/page_alloc.c:1235:#ifdef CONFIG_MEM_ALLOC_PROFILING\nmm/page_alloc.c-1236-\n--\nmm/page_alloc.c=1301=static inline void pgalloc_tag_sub_pages(struct alloc_tag tag, unsigned int nr)\n--\nmm/page_alloc.c-1306-\nmm/page_alloc.c:1307:#else / CONFIG_MEM_ALLOC_PROFILING /\nmm/page_alloc.c-1308-\n--\nmm/page_alloc.c=1312=static inline void pgalloc_tag_sub_pages(struct alloc_tag tag, unsigned int nr) {}\nmm/page_alloc.c-1313-\nmm/page_alloc.c:1314:#endif /* CONFIG_MEM_ALLOC_PROFILING /\nmm/page_alloc.c-1315-\n--\nmm/page_ext.c=80=static struct page_ext_operations page_ext_ops[] __initdata = {\n--\nmm/page_ext.c-86-#endif\nmm/page_ext.c:87:#ifdef CONFIG_MEM_ALLOC_PROFILING\nmm/page_ext.c-88-\t\u0026page_alloc_tagging_ops,\n--\nmm/page_ext.c=100=static unsigned long total_usage;\nmm/page_ext.c-101-\nmm/page_ext.c:102:#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG\nmm/page_ext.c-103-/\n--\nmm/percpu-internal.h=35=struct pcpuobj_ext {\n--\nmm/percpu-internal.h-38-#endif\nmm/percpu-internal.h:39:#ifdef CONFIG_MEM_ALLOC_PROFILING\nmm/percpu-internal.h-40-\tunion codetag_ref\ttag;\n--\nmm/percpu-internal.h-43-\nmm/percpu-internal.h:44:#if defined(CONFIG_MEMCG) \|\| defined(CONFIG_MEM_ALLOC_PROFILING)\nmm/percpu-internal.h-45-#define NEED_PCPUOBJ_EXT\n--\nmm/percpu-internal.h=90=static inline bool need_pcpuobj_ext(void)\nmm/percpu-internal.h-91-{\nmm/percpu-internal.h:92:\tif (IS_ENABLED(CONFIG_MEM_ALLOC_PROFILING))\nmm/percpu-internal.h-93-\t\treturn true;\n--\nmm/percpu.c=1690=static void pcpu_memcg_free_hook(struct pcpu_chunk chunk, int off, size_t size)\n--\nmm/percpu.c-1694-\nmm/percpu.c:1695:#ifdef CONFIG_MEM_ALLOC_PROFILING\nmm/percpu.c-1696-static void pcpu_alloc_tag_alloc_hook(struct pcpu_chunk chunk, int off,\n--\nmm/show_mem.c=408=void __show_mem(unsigned int filter, const nodemask_t nodemask,\n--\nmm/show_mem.c-434-#endif\nmm/show_mem.c:435:#ifdef CONFIG_MEM_ALLOC_PROFILING\nmm/show_mem.c-436-\tstatic DEFINE_SPINLOCK(mem_alloc_profiling_spinlock);\n--\nmm/slab.h=604=struct slabobj_ext {\n--\nmm/slab.h-612-#endif\nmm/slab.h:613:#ifdef CONFIG_MEM_ALLOC_PROFILING\nmm/slab.h-614-\t\tunion codetag_ref _ctref;\n--\nmm/slab.h-618-\nmm/slab.h:619:#ifdef CONFIG_MEM_ALLOC_PROFILING\nmm/slab.h:620:DECLARE_STATIC_KEY_MAYBE(CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT,\nmm/slab.h-621-\t\t\t slab_obj_ext_has_codetag_key);\n--\nmm/slab.h=623=static inline bool slab_obj_ext_has_codetag(void)\nmm/slab.h-624-{\nmm/slab.h:625:\treturn static_branch_maybe(CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT,\nmm/slab.h-626-\t\t\t\t \u0026slab_obj_ext_has_codetag_key);\n--\nmm/slab.h=807=slab_obj_ext_set_objcg(struct slab slab, struct slabobj_ext obj_ext,\n--\nmm/slab.h-816-\nmm/slab.h:817:#ifdef CONFIG_MEM_ALLOC_PROFILING\nmm/slab.h-818-static inline union codetag_ref \n--\nmm/slub.c=214=static DEFINE_STATIC_KEY_FALSE(strict_numa);\n--\nmm/slub.c-216-\nmm/slub.c:217:#ifdef CONFIG_MEM_ALLOC_PROFILING\nmm/slub.c:218:DEFINE_STATIC_KEY_MAYBE(CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT,\nmm/slub.c-219-\t\t\tslab_obj_ext_has_codetag_key);\n--\nmm/slub.c=2069=static inline void dec_slabs_node(struct kmem_cache s, int node,\n--\nmm/slub.c-2086-\nmm/slub.c:2087:#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG\nmm/slub.c-2088-\n--\nmm/slub.c=2124=static inline void handle_failed_objexts_alloc(struct slab slab,\n--\nmm/slub.c-2149-\nmm/slub.c:2150:#else / CONFIG_MEM_ALLOC_PROFILING_DEBUG /\nmm/slub.c-2151-\n--\nmm/slub.c=2154=static inline void handle_failed_objexts_alloc(struct slab slab,\n--\nmm/slub.c-2156-\nmm/slub.c:2157:#endif /* CONFIG_MEM_ALLOC_PROFILING_DEBUG /\nmm/slub.c-2158-\n--\nmm/slub.c=2346=static inline void alloc_slab_obj_exts_early(struct kmem_cache s,\n--\nmm/slub.c-2352-\nmm/slub.c:2353:#ifdef CONFIG_MEM_ALLOC_PROFILING\nmm/slub.c-2354-\n--\nmm/slub.c=2469=static void __init slab_obj_ext_has_codetag_init(void)\n--\nmm/slub.c-2480-\nmm/slub.c:2481:#else /* CONFIG_MEM_ALLOC_PROFILING /\nmm/slub.c-2482-\n--\nmm/slub.c=2495=static inline void slab_obj_ext_has_codetag_init(void)\n--\nmm/slub.c-2498-\nmm/slub.c:2499:#endif / CONFIG_MEM_ALLOC_PROFILING */\nmm/slub.c-2500-\n" }
5/2	2026/09/15 07:27	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 14772 output: 34 thoughts: 34 Thoughts: Investigating the Dependencies of `CONFIG_MEM_ALLOC_PROFILING` Alright, let's dive right in. My first thought is to get a handle on the dependencies for `CONFIG_MEM_ALLOC_PROFILING`. I know the Kconfig files are my go-to for configuration options, and I'm pretty sure `mm/Kconfig.debug` is where I'll find the relevant definitions and dependencies for this memory allocation profiling feature. Specifically, I'm going to jump to around line 324; that's usually where I start looking in that file. Hopefully, it'll be straightforward and I can quickly ascertain any requirements or pre-requisites for enabling this. No need to waste time guessing; let's get the information directly and move on.
6/2	2026/09/15 07:28	tool	read-file	0m Args: { "File": "mm/Kconfig.debug", "FirstLine": 320, "LineCount": 40 } Results: { "Contents": " 320:\t\t overhead in the page fault path.\n 321:\t\n 322:\t\t If in doubt, say N.\n 323:\t\n 324:\tconfig MEM_ALLOC_PROFILING\n 325:\t\tbool \"Enable memory allocation profiling\"\n 326:\t\tdefault n\n 327:\t\tdepends on MMU\n 328:\t\tdepends on PROC_FS\n 329:\t\tselect CODE_TAGGING\n 330:\t\tselect PAGE_EXTENSION\n 331:\t\tselect SLAB_OBJ_EXT\n 332:\t\thelp\n 333:\t\t Track allocation source code and record total allocation size\n 334:\t\t initiated at that code location. The mechanism can be used to track\n 335:\t\t memory leaks with a low performance and memory impact.\n 336:\t\n 337:\tconfig MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT\n 338:\t\tbool \"Enable memory allocation profiling by default\"\n 339:\t\tdefault y\n 340:\t\tdepends on MEM_ALLOC_PROFILING\n 341:\t\n 342:\tconfig MEM_ALLOC_PROFILING_DEBUG\n 343:\t\tbool \"Memory allocation profiler debugging\"\n 344:\t\tdefault n\n 345:\t\tdepends on MEM_ALLOC_PROFILING\n 346:\t\tselect MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT\n 347:\t\thelp\n 348:\t\t Adds warnings with helpful error messages for memory allocation\n 349:\t\t profiling.\n" }
7/2	2026/09/15 07:28	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 15417 output: 27 thoughts: 22 Thoughts: Here's my take on those thoughts, tailored for an expert audience: Investigating the CODE_TAGGING Variable's Definition Okay, so we need to track down where `CODE_TAGGING` is actually defined, which is crucial for understanding its behavior and potential interactions. While the initial instinct might be a quick grep, I want to be thorough. I'll need to double-check that `lib/Kconfig` (or wherever the project's configuration system, be it Kconfig or a similar mechanism, resides) to ensure that the primary definition is present. I need to know where I can control this variable. There might be some subtle conditional logic there that's crucial to debug. This is a common pattern in build systems and I want to be 100% sure I'm not missing anything obvious and this will give me a proper context for understanding its impact on the rest of the build.
8/2	2026/09/15 07:28	tool	grepper	0m Args: { "Expression": "config CODE_TAGGING", "PathPrefix": "lib/" } Results: { "Output": "lib/Kconfig.debug=1014=config DEBUG_STACKOVERFLOW\n--\nlib/Kconfig.debug-1031-\nlib/Kconfig.debug:1032:config CODE_TAGGING\nlib/Kconfig.debug-1033-\tbool\n" }
9/2	2026/09/15 07:28	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 15738 output: 35 thoughts: 21 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: Diving into Debugging Configuration Okay, let's get down to brass tacks. I need to understand this specific debugging configuration and its implications. Line 1032 in `lib/Kconfig.debug` is the obvious place to start. This file, as we all know, houses crucial definitions and dependencies that directly impact how we troubleshoot the kernel. I'm immediately curious about what this particular entry controls. Is it a feature flag? A default setting for a particular debug level? Perhaps a dependency on another configuration option? Depending on what it is I know I will need to understand what it unlocks (or locks). My goal here is not just to understand the syntax of that line but to piece together its role in the larger debugging strategy. I anticipate this line will be a key to figuring out how to get to the bottom of the current issue.
10/2	2026/09/15 07:28	tool	read-file	0m Args: { "File": "lib/Kconfig.debug", "FirstLine": 1030, "LineCount": 20 } Results: { "Contents": "1030:\t\t If in doubt, say \"N\".\n1031:\t\n1032:\tconfig CODE_TAGGING\n1033:\t\tbool\n1034:\t\tselect KALLSYMS\n1035:\t\n1036:\tsource \"lib/Kconfig.kasan\"\n1037:\tsource \"lib/Kconfig.kfence\"\n1038:\tsource \"lib/Kconfig.kmsan\"\n1039:\t\n1040:\tendmenu # \"Memory Debugging\"\n1041:\t\n1042:\tconfig DEBUG_SHIRQ\n1043:\t\tbool \"Debug shared IRQ handlers\"\n1044:\t\tdepends on DEBUG_KERNEL\n1045:\t\thelp\n1046:\t\t Enable this to generate a spurious interrupt just before a shared\n1047:\t\t interrupt handler is deregistered (generating one when registering\n1048:\t\t is currently disabled). Drivers need to handle this correctly. Some\n1049:\t\t don't and need to be caught.\n" }
11/2	2026/09/15 07:28	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 16267 output: 37 thoughts: 1371 Thoughts: Module Loading Patch Triage Okay, so I'm looking at this patch and immediately, my focus goes to `MODULES` configuration in `kernel/module/`. Kernel modules are definitely configurable, so that's a good starting point. Let's see... the patch touches a bunch of files related to module loading and codetags/alloc_tag: `include/linux/module.h`, `kernel/module/internal.h`, `kernel/module/kallsyms.c`, `kernel/module/main.c`, `kernel/module/sysfs.c`, `lib/codetag.c`, and `mm/alloc_tag.c`. That's a pretty broad scope, which piques my interest. The changes appear to be concentrated in the core module loading logic. Specifically, in `kernel/module/main.c`, functions like `layout_and_allocate()`, `apply_relocations()`, `allocate_codetag_sections()`, and `move_module()` are all called during module loading via system calls like `init_module` and `finit_module`. Sysfs interaction is also happening, with functions such as `add_sect_attrs()` and `add_notes_attrs()` getting involved during module loading, and `is_core_symbol()` and `layout_symtab()` / `add_kallsyms()` called, too. `lib/codetag.c` adds `codetag_module_init()` and `codetag_unload_module()`, and `mm/alloc_tag.c` has a slew of functions like `shutdown_mem_profiling` and `load_module`. Wait, can Syzkaller load modules? Aha! Syzkaller does execute `init_module` and `finit_module`! It's actually using the syscalls for fuzzing purposes, probing module loading paths, and also testing sysfs, procfs and memory allocation. Right, back to the core triage philosophy: REACHABILITY IS KEY. Can the modified code be executed in a standard virtualized environment like QEMU? Absolutely. Module loading via syscalls, `/proc/allocinfo` access, and alloc_tagging during module loads are all reachable. So, let's break this down further: 1. `kernel/module/main.c`, `kernel/module/kallsyms.c`, and `kernel/module/sysfs.c` are core module loader subsystems. 2. `mm/alloc_tag.c` is memory management code. 3. `lib/codetag.c` is codetag management. All are in core kernel and reachable in QEMU. That's good news. Now, let's dig into the details. I need to get a better handle on the actual changes, so let's check the diff directly. Okay, let's look at the diff: 1. `include/linux/module.h` introduces a `MOD_STANDALONE` enum. 2. `kernel/module/internal.h` defines a `SH_ENTSIZE_STANDALONE` macro. 3. `kernel/module/kallsyms.c` had some changes in `is_core_symbol()`. Why? `is_core_symbol()`'s code looks a little different around lines 80-110. Let's dig into that change specifically.
12/2	2026/09/15 07:28	tool	read-file	0m Args: { "File": "kernel/module/kallsyms.c", "FirstLine": 70, "LineCount": 50 } Results: { "Contents": " 70:\t\t}\n 71:\t\tif (strstarts(info-\u003esecstrings + sechdrs[sym-\u003est_shndx].sh_name,\n 72:\t\t\t \".debug\")) {\n 73:\t\t\treturn 'n';\n 74:\t\t}\n 75:\t\treturn '?';\n 76:\t}\n 77:\t\n 78:\tstatic bool is_core_symbol(const Elf_Sym src, const Elf_Shdr sechdrs,\n 79:\t\t\t\t unsigned int shnum)\n 80:\t{\n 81:\t\tconst Elf_Shdr sec;\n 82:\t\tenum mod_mem_type type;\n 83:\t\n 84:\t\tif (src-\u003est_shndx == SHN_UNDEF \|\|\n 85:\t\t src-\u003est_shndx \u003e= shnum \|\|\n 86:\t\t !src-\u003est_name)\n 87:\t\t\treturn false;\n 88:\t\n 89:\t\tsec = sechdrs + src-\u003est_shndx;\n 90:\t\ttype = sec-\u003esh_entsize \u003e\u003e SH_ENTSIZE_TYPE_SHIFT;\n 91:\t\tif (!(sec-\u003esh_flags \u0026 SHF_ALLOC)\n 92:\t#ifndef CONFIG_KALLSYMS_ALL\n 93:\t\t \|\| !(sec-\u003esh_flags \u0026 SHF_EXECINSTR)\n 94:\t#endif\n 95:\t\t \|\| mod_mem_type_is_init(type))\n 96:\t\t\treturn false;\n 97:\t\n 98:\t\treturn true;\n 99:\t}\n 100:\t\n 101:\t/\n 102:\t * We only allocate and copy the strings needed by the parts of symtab\n 103:\t * we keep. This is simple, but has the effect of making multiple\n 104:\t * copies of duplicates. We could be more sophisticated, see\n 105:\t * linux-kernel thread starting with\n 106:\t * \u003c73defb5e4bca04a6431392cc341112b1@localhost\u003e.\n 107:\t /\n 108:\tvoid layout_symtab(struct module mod, struct load_info info)\n 109:\t{\n 110:\t\tElf_Shdr symsect = info-\u003esechdrs + info-\u003eindex.sym;\n 111:\t\tElf_Shdr strsect = info-\u003esechdrs + info-\u003eindex.str;\n 112:\t\tconst Elf_Sym src;\n 113:\t\tunsigned int i, nsrc, ndst, strtab_size = 0;\n 114:\t\tstruct module_memory mod_mem_data = \u0026mod-\u003emem[MOD_DATA];\n 115:\t\tstruct module_memory mod_mem_init_data = \u0026mod-\u003emem[MOD_INIT_DATA];\n 116:\t\n 117:\t\t/* Put symbol section at end of init part of module. */\n 118:\t\tsymsect-\u003esh_flags \|= SHF_ALLOC;\n 119:\t\tsymsect-\u003esh_entsize = module_get_offset_and_type(mod, MOD_INIT_DATA,\n" }
13/2	2026/09/15 07:28	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 19237 output: 36 thoughts: 159 Thoughts: My Current Reasoning Process Okay, let's dive into this. The function `is_core_symbol`... I need to understand why that exists and what it's checking for. My initial thought is to remember the old implementation, specifically that bit manipulation: `info->sechdrs[info->index.pcpu].sh_flags &= ~(unsigned long)SHF_ALLOC;`. Ah, right, that removed the `SHF_ALLOC` flag from the per-CPU section. Because of that change, the check `if (src->st_shndx == pcpundx) return true;` was necessary – it was working around the fact that `pcpu` wasn't marked as allocatable any longer. It seems like it was a consequence of the previous method. Now, things are different. In the `layout_and_allocate` function, they are now setting `info->sechdrs[info->index.pcpu].sh_entsize = SH_ENTSIZE_STANDALONE;` and, crucially, keeping the `SHF_ALLOC` flag. This is a significant change! I need to quickly confirm the current implementation of `layout_and_allocate`. So, I'll need to double-check the behavior of `layout_and_allocate` in `kernel/module/main.c` because this changes everything! This needs to be checked.
14/2	2026/09/15 07:28	tool	read-file	0m Args: { "File": "kernel/module/main.c", "FirstLine": 2965, "LineCount": 45 } Results: { "Contents": "2965:\t\n2966:\t\terr = module_enforce_rwx_sections(info-\u003ehdr, info-\u003esechdrs,\n2967:\t\t\t\t\t\t info-\u003esecstrings, info-\u003emod);\n2968:\t\tif (err \u003c 0)\n2969:\t\t\treturn ERR_PTR(err);\n2970:\t\n2971:\t\t/* Repurpose sh_entsize to track where each section is allocated. /\n2972:\t\tfor (i = 0; i \u003c info-\u003ehdr-\u003ee_shnum; i++)\n2973:\t\t\tinfo-\u003esechdrs[i].sh_entsize = ~0UL;\n2974:\t\n2975:\t\t/ We will do a special allocation for per-cpu sections later. /\n2976:\t\tif (info-\u003eindex.pcpu)\n2977:\t\t\tinfo-\u003esechdrs[info-\u003eindex.pcpu].sh_entsize = SH_ENTSIZE_STANDALONE;\n2978:\t\n2979:\t\t/\n2980:\t\t * Mark relevant sections as SHF_RO_AFTER_INIT so layout_sections() can\n2981:\t\t * put them in the right place.\n2982:\t\t * Note: ro_after_init sections also have SHF_{WRITE,ALLOC} set.\n2983:\t\t /\n2984:\t\tmodule_mark_ro_after_init(info-\u003ehdr, info-\u003esechdrs, info-\u003esecstrings);\n2985:\t\n2986:\t\t/ Allow codetag sections to be allocated separately first. /\n2987:\t\terr = allocate_codetag_sections(info);\n2988:\t\tif (err)\n2989:\t\t\treturn ERR_PTR(err);\n2990:\t\n2991:\t\t/ Determine total sizes and put offsets in sh_entsize. /\n2992:\t\tlayout_sections(info-\u003emod, info);\n2993:\t\tlayout_symtab(info-\u003emod, info);\n2994:\t\n2995:\t\t/ Allocate and move to the final place /\n2996:\t\terr = move_module(info-\u003emod, info);\n2997:\t\tif (err) {\n2998:\t\t\tcodetag_free_module_sections(info-\u003emod);\n2999:\t\t\treturn ERR_PTR(err);\n3000:\t\t}\n3001:\t\n3002:\t\t/ Module has been copied to its final place now: return it. /\n3003:\t\tmod = (void )info-\u003esechdrs[info-\u003eindex.mod].sh_addr;\n3004:\t\tkmemleak_load_module(mod, info);\n3005:\t\tcodetag_module_replaced(info-\u003emod, mod);\n3006:\t\n3007:\t\treturn mod;\n3008:\t}\n3009:\t\n" }
15/2	2026/09/15 07:28	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 20471 output: 36 thoughts: 371 Thoughts: Analyzing `is_core_symbol()` in `kallsyms.c` Okay, hold on a second. I'm looking at the `is_core_symbol()` function in `kernel/module/kallsyms.c`. Let's see... it checks a few things. First, it extracts the `type` from `sec->sh_entsize` using a bit shift operation. It's skipping symbols in sections that aren't allocated, aren't executable (unless `CONFIG_KALLSYMS_ALL` is defined), or are of a certain memory type. But wait a minute, what happens when `sh_entsize` is equal to `SH_ENTSIZE_STANDALONE`? Let me look that up real quick... Okay, `SH_ENTSIZE_STANDALONE` is defined using bitwise operations and `MOD_STANDALONE`. Specifically, it shifts `MOD_STANDALONE` into a particular position within `sh_entsize`. I need to figure out how that affects the `type` extraction. Right, so it's a bit field. The `type` is effectively the lower bits of `sh_entsize`... That makes sense. Let's dig deeper; what does `mod_mem_type_is_init(type)` do? I need to check the definition of that function to fully grasp the intent here.
16/2	2026/09/15 07:28	tool	grepper	0m Args: { "Expression": "mod_mem_type_is_init", "PathPrefix": "include/linux/module.h" } Results: { "Output": "include/linux/module.h=318=enum mod_mem_type {\n--\ninclude/linux/module.h-332-\ninclude/linux/module.h:333:#define mod_mem_type_is_init(type)\t\\\ninclude/linux/module.h-334-\t((type) == MOD_INIT_TEXT \|\|\t\\\n--\ninclude/linux/module.h-337-\ninclude/linux/module.h:338:#define mod_mem_type_is_core(type) (!mod_mem_type_is_init(type))\ninclude/linux/module.h-339-\n" }
17/2	2026/09/15 07:28	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 21345 output: 35 thoughts: 17 Thoughts: Okay, here's my attempt at summarizing the thought process, as requested, in the first person and targeted towards an expert: Diving into the Module Definition Alright, let's get down to brass tacks. I need to understand the specifics of how this module works. My first step is to dig into the source code to get the definitive answer. The place to start is the header file, specifically, `include/linux/module.h`. That's where I expect to find the complete and authoritative definition, not just snippets. I'm going to look there to make sure I get the whole picture. Let's see what we've got.
18/2	2026/09/15 07:28	tool	read-file	0m Args: { "File": "include/linux/module.h", "FirstLine": 315, "LineCount": 30 } Results: { "Contents": " 315:\t\tstruct latch_tree_node node;\n 316:\t};\n 317:\t\n 318:\tenum mod_mem_type {\n 319:\t\tMOD_TEXT = 0,\n 320:\t\tMOD_DATA,\n 321:\t\tMOD_RODATA,\n 322:\t\tMOD_RO_AFTER_INIT,\n 323:\t\tMOD_INIT_TEXT,\n 324:\t\tMOD_INIT_DATA,\n 325:\t\tMOD_INIT_RODATA,\n 326:\t\n 327:\t\tMOD_MEM_NUM_TYPES,\n 328:\t\n 329:\t\tMOD_STANDALONE = -2,\n 330:\t\tMOD_INVALID = -1,\n 331:\t};\n 332:\t\n 333:\t#define mod_mem_type_is_init(type)\t\\\n 334:\t\t((type) == MOD_INIT_TEXT \|\|\t\\\n 335:\t\t (type) == MOD_INIT_DATA \|\|\t\\\n 336:\t\t (type) == MOD_INIT_RODATA)\n 337:\t\n 338:\t#define mod_mem_type_is_core(type) (!mod_mem_type_is_init(type))\n 339:\t\n 340:\t#define mod_mem_type_is_text(type)\t\\\n 341:\t\t ((type) == MOD_TEXT \|\|\t\t\\\n 342:\t\t (type) == MOD_INIT_TEXT)\n 343:\t\n 344:\t#define mod_mem_type_is_data(type) (!mod_mem_type_is_text(type))\n" }
19/2	2026/09/15 07:28	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 21987 output: 27 thoughts: 1005 Thoughts: Analyzing Module Section Handling Okay, let's break this down. First, I checked `mod_mem_type_is_init`, and confirmed `MOD_STANDALONE` doesn't match the initialization types. Then, I saw that `.data..percpu` has `SHF_ALLOC` set, which means `is_core_symbol` identifies it as a core symbol when `CONFIG_KALLSYMS_ALL` is enabled. No special handling needed there. Now, I'm diving into `allocate_codetag_sections` in `kernel/module/main.c`. The code iterates through sections and, if a section needs a module-specific allocation, it attempts to allocate it with `codetag_alloc_module_section`. There's an important part here: if allocation fails with `-EAGAIN`, it's treated like a regular section allocation, and we `continue`. If successful, the section's `sh_entsize` is set to `SH_ENTSIZE_STANDALONE`. Next, in `__layout_sections`, I noticed that sections with `sh_entsize` set to `SH_ENTSIZE_STANDALONE` are skipped because `s->sh_entsize != ~0UL` is true. This continues with `move_module`, where sections with the `SH_ENTSIZE_STANDALONE` flag (like `.data..percpu` and codetag sections) are skipped due to the continue statement when that flag is true. Finally, in `sect_visible` from `kernel/module/sysfs.c`, the function excludes the percpu section (`i != info->index.pcpu`) if it isn't empty. Interestingly, I'm reminded that the `SHF_ALLOC` flag was removed from `.data..percpu` during `layout_and_allocate`. I should look into what `sect_empty` does, given this fact.
20/2	2026/09/15 07:29	tool	grepper	0m Args: { "Expression": "sect_empty", "PathPrefix": "kernel/module/" } Results: { "Output": "kernel/module/internal.h=366=void add_kallsyms(struct module mod, const struct load_info info);\nkernel/module/internal.h-367-\nkernel/module/internal.h:368:static inline bool sect_empty(const Elf_Shdr sect)\nkernel/module/internal.h-369-{\n--\nkernel/module/kallsyms.c=218=void init_build_id(struct module mod, const struct load_info info)\n--\nkernel/module/kallsyms.c-224-\t\tsechdr = \u0026info-\u003esechdrs[i];\nkernel/module/kallsyms.c:225:\t\tif (!sect_empty(sechdr) \u0026\u0026 sechdr-\u003esh_type == SHT_NOTE \u0026\u0026\nkernel/module/kallsyms.c-226-\t\t !build_id_parse_buf((void )sechdr-\u003esh_addr, mod-\u003ebuild_id,\n--\nkernel/module/sysfs.c=69=static bool sect_visible(const struct load_info *info, unsigned int i)\nkernel/module/sysfs.c-70-{\nkernel/module/sysfs.c:71:\treturn !sect_empty(\u0026info-\u003esechdrs[i]) \u0026\u0026 i != info-\u003eindex.pcpu;\nkernel/module/sysfs.c-72-}\n" }
21/2	2026/09/15 07:29	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 23787 output: 35 thoughts: 22 Thoughts: Here's my summary, as though I'm thinking through it: Diving into `sect_empty` Okay, let's get down to brass tacks. I need to understand what this macro, `sect_empty`, is doing in `kernel/module/internal.h`. Given my background in kernel internals, I'm already anticipating this probably has something to do with section management, particularly around module loading and unloading. I'm guessing it's a test or check – perhaps for an empty section, a section filled with padding, or a section not needing special handling. I'll need to figure out what it's defining the criteria as, how it's used, and the implications of it being true or false. Time to start digging!
22/2	2026/09/15 07:29	tool	read-file	0m Args: { "File": "kernel/module/internal.h", "FirstLine": 365, "LineCount": 15 } Results: { "Contents": " 365:\tvoid layout_symtab(struct module mod, struct load_info info);\n 366:\tvoid add_kallsyms(struct module mod, const struct load_info info);\n 367:\t\n 368:\tstatic inline bool sect_empty(const Elf_Shdr sect)\n 369:\t{\n 370:\t\treturn !(sect-\u003esh_flags \u0026 SHF_ALLOC) \|\| sect-\u003esh_size == 0;\n 371:\t}\n 372:\t#else / !CONFIG_KALLSYMS /\n 373:\tstatic inline void init_build_id(struct module mod, const struct load_info info) { }\n 374:\tstatic inline void layout_symtab(struct module mod, struct load_info info) { }\n 375:\tstatic inline void add_kallsyms(struct module mod, const struct load_info info) { }\n 376:\t#endif / CONFIG_KALLSYMS /\n 377:\t\n 378:\t#ifdef CONFIG_SYSFS\n 379:\tint mod_sysfs_setup(struct module mod, const struct load_info *info,\n" }
23/2	2026/09/15 07:29	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 24322 output: 33 thoughts: 561 Thoughts: Analyzing Section Visibility and Memory Management Okay, so I'm looking at this section flag logic and it seems we've changed how we're determining if a section is "empty." Originally, `sect_empty()` checked if `!(sect->sh_flags & SHF_ALLOC) \|\| sect->sh_size == 0`. The pcpu section specifically had the `SHF_ALLOC` flag removed, causing `sect_empty()` to return true. Now that we're keeping the `SHF_ALLOC` flag on the pcpu section, the `sect_visible()` function has been introduced, which explicitly checks `!sect_empty(...) && i != info->index.pcpu`. Got it, that's clean. Now, let's dive into these `lib/codetag.c` and `mm/alloc_tag.c` files. In `lib/codetag.c`, within the `codetag_module_init` function, we have an interesting error handling path. If there's an error loading a codetag module, we free the memory (`kfree(cmod)`). Crucially, if the error is `-EOPNOTSUPP`, we still return 0. This suggests that a module might be loaded without its associated tag. The follow-up in `codetag_unload_module` also notes that a module failing load, with `-EOPNOTSUPP` might still hold reserved section memory. This is critical. We free the memory with `cttype->desc.free_section_mem(mod, true)`. Now, turning to `mm/alloc_tag.c`, I see `remove_allocinfo_file` and that it uses `schedule_work()`. We are removing the `/proc/allocinfo` file here. That's a classic race condition and it strikes me as important. We are likely using `schedule_work()` here because directly calling `remove_proc_entry(ALLOCINFO_FILE_NAME, NULL)` might lead to deadlocks or attempts to sleep in an atomic context, or something similar to that. I'll need to double-check where `shutdown_mem_profiling` can be called from. This is related to the memory profiling support and the removal of the proc entry after we disable the profiling.
24/2	2026/09/15 07:29	tool	grepper	0m Args: { "Expression": "shutdown_mem_profiling", "PathPrefix": "mm/alloc_tag.c" } Results: { "Output": "mm/alloc_tag.c=600=static DECLARE_WORK(remove_allocinfo_work, remove_allocinfo_file);\nmm/alloc_tag.c-601-\nmm/alloc_tag.c:602:static void shutdown_mem_profiling(bool remove_file)\nmm/alloc_tag.c-603-{\n--\nmm/alloc_tag.c=615=void __init alloc_tag_sec_init(void)\n--\nmm/alloc_tag.c-632-\tif (kernel_tags.count \u003e (1UL \u003c\u003c NR_UNUSED_PAGEFLAG_BITS)) {\nmm/alloc_tag.c:633:\t\tshutdown_mem_profiling(false); /* allocinfo file does not exist yet /\nmm/alloc_tag.c-634-\t\tpr_err(\"%lu allocation tags cannot be references using %d available page flag bits. Memory allocation profiling is disabled!\\n\",\n--\nmm/alloc_tag.c=899=static void reserve_module_tags(struct module *mod, unsigned long size,\n--\nmm/alloc_tag.c-918-\tif (!ensure_alignment(align, \u0026prepend)) {\nmm/alloc_tag.c:919:\t\tshutdown_mem_profiling(true);\nmm/alloc_tag.c-920-\t\tpr_err(\"%s: alignment %lu is incompatible with allocation tag indexing. Memory allocation profiling is disabled!\\n\",\n--\nmm/alloc_tag.c-969-\t\tif (!tags_addressable()) {\nmm/alloc_tag.c:970:\t\t\tshutdown_mem_profiling(true);\nmm/alloc_tag.c-971-\t\t\tpr_warn_once(\"With module %s there are too many tags to fit in %d page flag bits. Memory allocation profiling is disabled!\\n\",\n--\nmm/alloc_tag.c-979-\t\tif (grow_res) {\nmm/alloc_tag.c:980:\t\t\tshutdown_mem_profiling(true);\nmm/alloc_tag.c-981-\t\t\tpr_err(\"Failed to allocate memory for allocation tags in the module %s. Memory allocation profiling is disabled!\\n\",\n--\nmm/alloc_tag.c=1347=static int __init alloc_tag_init(void)\n--\nmm/alloc_tag.c-1371-\t\tpr_err(\"Failed to reserve address space for module tags, errno = %d\\n\", res);\nmm/alloc_tag.c:1372:\t\tshutdown_mem_profiling(false);\nmm/alloc_tag.c-1373-\t\treturn res;\n--\nmm/alloc_tag.c-1379-\t\tfree_mod_tags_mem();\nmm/alloc_tag.c:1380:\t\tshutdown_mem_profiling(false);\nmm/alloc_tag.c-1381-\t\treturn PTR_ERR(alloc_tag_cttype);\n--\nmm/alloc_tag.c-1385-\t\tpr_err(\"Failed to create %s file\\n\", ALLOCINFO_FILE_NAME);\nmm/alloc_tag.c:1386:\t\tshutdown_mem_profiling(false);\nmm/alloc_tag.c-1387-\t\treturn -ENOMEM;\n" }
25/2	2026/09/15 07:29	llm	patch-evaluator	1m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 26213 output: 34 thoughts: 61 Thoughts: Analyzing Potential Race Conditions in Memory Profiling Okay, let's dive into this. The code is calling `shutdown_mem_profiling(true)`, and I see that it's being done while the `codetag_lock` is held. Now, that immediately flags something for me. I need to understand what's happening within the `reserve_module_tags` function. I also see concerns. I need to confirm that there's no potential for a race condition here. To do that, I'm going to carefully inspect the locking behavior in `codetag_alloc_module_section` and `reserve_module_tags`. I need to ensure that the lock hierarchy and acquisition order is correct and that the `codetag_lock` doesn't interact in an unsafe way with any other locks involved in memory management during profiling shutdown. I can't afford any deadlocks, or corruption. This warrants a very close inspection.
26/2	2026/09/15 07:31	tool	grepper	0m Args: { "Expression": "codetag_alloc_module_section", "PathPrefix": "lib/codetag.c" } Results: { "Output": "lib/codetag.c=255=bool codetag_needs_module_section(struct module mod, const char name,\n--\nlib/codetag.c-282-\nlib/codetag.c:283:void codetag_alloc_module_section(struct module mod, const char *name,\nlib/codetag.c-284-\t\t\t\t unsigned long size, unsigned int prepend,\n" }
27/2	2026/09/15 07:31	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 26620 output: 34 thoughts: 19 Thoughts: Here's my summary, as if I were thinking these thoughts: Analyzing `lib/codetag.c` around Line 283 Okay, let's dive into `lib/codetag.c`. I'm going to zero in on the code around line 283. I expect there might be something interesting there; given my understanding of the codebase and the usual patterns in this part of the library, that's a likely spot for a particular kind of logic or perhaps an important data structure interaction. I'll need to assess its context, of course – what functions are calling it, what variables are in scope, what's it trying to do in relation to the code tag processing? Gotta keep an eye out for potential edge cases, any memory management issues, and how it handles different types of tags. Let's start by scanning the surrounding lines to get a clearer picture. Alright, let's see what we find.
28/2	2026/09/15 07:31	tool	read-file	0m Args: { "File": "lib/codetag.c", "FirstLine": 275, "LineCount": 40 } Results: { "Contents": " 275:\t\t\t\tbreak;\n 276:\t\t\t}\n 277:\t\t}\n 278:\t\tmutex_unlock(\u0026codetag_lock);\n 279:\t\n 280:\t\treturn ret;\n 281:\t}\n 282:\t\n 283:\tvoid codetag_alloc_module_section(struct module mod, const char name,\n 284:\t\t\t\t\t unsigned long size, unsigned int prepend,\n 285:\t\t\t\t\t unsigned long align)\n 286:\t{\n 287:\t\tconst char type_name = name + strlen(CODETAG_SECTION_PREFIX);\n 288:\t\tstruct codetag_type cttype;\n 289:\t\tvoid ret = ERR_PTR(-EINVAL);\n 290:\t\n 291:\t\tmutex_lock(\u0026codetag_lock);\n 292:\t\tlist_for_each_entry(cttype, \u0026codetag_types, link) {\n 293:\t\t\tif (strcmp(type_name, cttype-\u003edesc.section) == 0) {\n 294:\t\t\t\tif (WARN_ON(!cttype-\u003edesc.alloc_section_mem))\n 295:\t\t\t\t\tbreak;\n 296:\t\n 297:\t\t\t\tdown_write(\u0026cttype-\u003emod_lock);\n 298:\t\t\t\tret = cttype-\u003edesc.alloc_section_mem(mod, size, prepend, align);\n 299:\t\t\t\tup_write(\u0026cttype-\u003emod_lock);\n 300:\t\t\t\tbreak;\n 301:\t\t\t}\n 302:\t\t}\n 303:\t\tmutex_unlock(\u0026codetag_lock);\n 304:\t\n 305:\t\treturn ret;\n 306:\t}\n 307:\t\n 308:\tvoid codetag_free_module_sections(struct module mod)\n 309:\t{\n 310:\t\tstruct codetag_type cttype;\n 311:\t\n 312:\t\tmutex_lock(\u0026codetag_lock);\n 313:\t\tlist_for_each_entry(cttype, \u0026codetag_types, link) {\n 314:\t\t\tif (!cttype-\u003edesc.free_section_mem)\n" }
29/2	2026/09/15 07:31	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 27457 output: 26 thoughts: 191 Thoughts: My Analysis of a Potential Locking Issue in the Code Okay, so I'm digging into this `codetag_alloc_module_section` function, and I'm seeing a potential race condition that's got my attention. First, we grab `codetag_lock` with a mutex, and then we take `cttype->mod_lock` with a write semaphore. The real kicker is this call to `cttype->desc.alloc_section_mem(...)`, which ultimately calls `reserve_module_tags`. Now, that's where things get interesting. If the module tags are somehow unaddressable or if growing them fails within `reserve_module_tags`, the code calls `shutdown_mem_profiling(true)`. Here's where my Spidey sense starts tingling: if this shutdown function synchronously removes the `/proc/allocinfo` proc entry using `remove_proc_entry(ALLOCINFO_FILE_NAME, NULL)`, we could have a nasty blocking situation. This `remove_proc_entry` call has the potential to block or acquire proc fs locks, and I can envision scenarios where readers of `/proc/allocinfo` might also be trying to acquire `codetag_lock`. That's the crux of it: a reader of `/proc/allocinfo` could be holding or contending for `codetag_lock` while `shutdown_mem_profiling` attempts to remove the proc entry. This is a classic deadlock or contention scenario in the making. My immediate next step is to verify if any reader of `/proc/allocinfo` actually grabs `codetag_lock` or something similar. Time to break out `grep` and search the code for any instances of `codetag_lock` being accessed in conjunction with `/proc/allocinfo` reads. This is likely the smoking gun I need to confirm the issue and assess its severity.
30/2	2026/09/15 07:32	tool	grepper	0m Args: { "Expression": "codetag_lock", "PathPrefix": "lib/" } Results: { "Output": "lib/codetag.c=31=struct codetag_module {\n--\nlib/codetag.c-36-\nlib/codetag.c:37:static DEFINE_MUTEX(codetag_lock);\nlib/codetag.c-38-static LIST_HEAD(codetag_types);\nlib/codetag.c-39-\nlib/codetag.c:40:void codetag_lock_module_list(struct codetag_type cttype)\nlib/codetag.c-41-{\n--\nlib/codetag.c=255=bool codetag_needs_module_section(struct module mod, const char name,\n--\nlib/codetag.c-265-\ttype_name = name + strlen(CODETAG_SECTION_PREFIX);\nlib/codetag.c:266:\tmutex_lock(\u0026codetag_lock);\nlib/codetag.c-267-\tlist_for_each_entry(cttype, \u0026codetag_types, link) {\n--\nlib/codetag.c-277-\t}\nlib/codetag.c:278:\tmutex_unlock(\u0026codetag_lock);\nlib/codetag.c-279-\n--\nlib/codetag.c=283=void codetag_alloc_module_section(struct module mod, const char name,\n--\nlib/codetag.c-290-\nlib/codetag.c:291:\tmutex_lock(\u0026codetag_lock);\nlib/codetag.c-292-\tlist_for_each_entry(cttype, \u0026codetag_types, link) {\n--\nlib/codetag.c-302-\t}\nlib/codetag.c:303:\tmutex_unlock(\u0026codetag_lock);\nlib/codetag.c-304-\n--\nlib/codetag.c=308=void codetag_free_module_sections(struct module mod)\n--\nlib/codetag.c-311-\nlib/codetag.c:312:\tmutex_lock(\u0026codetag_lock);\nlib/codetag.c-313-\tlist_for_each_entry(cttype, \u0026codetag_types, link) {\n--\nlib/codetag.c-320-\t}\nlib/codetag.c:321:\tmutex_unlock(\u0026codetag_lock);\nlib/codetag.c-322-}\n--\nlib/codetag.c=324=void codetag_module_replaced(struct module mod, struct module new_mod)\n--\nlib/codetag.c-327-\nlib/codetag.c:328:\tmutex_lock(\u0026codetag_lock);\nlib/codetag.c-329-\tlist_for_each_entry(cttype, \u0026codetag_types, link) {\n--\nlib/codetag.c-336-\t}\nlib/codetag.c:337:\tmutex_unlock(\u0026codetag_lock);\nlib/codetag.c-338-}\n--\nlib/codetag.c=340=int codetag_load_module(struct module mod)\n--\nlib/codetag.c-347-\nlib/codetag.c:348:\tmutex_lock(\u0026codetag_lock);\nlib/codetag.c-349-\tlist_for_each_entry(cttype, \u0026codetag_types, link) {\n--\nlib/codetag.c-353-\t}\nlib/codetag.c:354:\tmutex_unlock(\u0026codetag_lock);\nlib/codetag.c-355-\n--\nlib/codetag.c=359=void codetag_unload_module(struct module mod)\n--\nlib/codetag.c-368-\nlib/codetag.c:369:\tmutex_lock(\u0026codetag_lock);\nlib/codetag.c-370-\tlist_for_each_entry(cttype, \u0026codetag_types, link) {\n--\nlib/codetag.c-399-\t}\nlib/codetag.c:400:\tmutex_unlock(\u0026codetag_lock);\nlib/codetag.c-401-}\n--\nlib/codetag.c=405=codetag_register_type(const struct codetag_type_desc desc)\n--\nlib/codetag.c-425-\nlib/codetag.c:426:\tmutex_lock(\u0026codetag_lock);\nlib/codetag.c-427-\tlist_add_tail(\u0026cttype-\u003elink, \u0026codetag_types);\nlib/codetag.c:428:\tmutex_unlock(\u0026codetag_lock);\nlib/codetag.c-429-\n" }
31/2	2026/09/15 07:32	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 29259 output: 28 thoughts: 23 Thoughts: Here's my summary, as though I'm thinking through this process: Diving into Allocation Information Okay, so I need to understand how this memory allocation is working, right? The first thing that comes to mind is the `allocinfo_proc_ops` in `mm/alloc_tag.c`. I need to see how the system is gathering and reporting this allocation information. Let's head over there and take a closer look at that specific part of the code. That seems like the logical starting point for tracing this down. It should be a good place to start digging into the details of the allocation tracking mechanism.
32/2	2026/09/15 07:32	tool	grepper	0m Args: { "Expression": "allocinfo_proc_ops", "PathPrefix": "mm/" } Results: { "Output": "mm/alloc_tag.c=470=static long allocinfo_compat_ioctl(struct file *file, unsigned int cmd,\n--\nmm/alloc_tag.c-476-\nmm/alloc_tag.c:477:static const struct proc_ops allocinfo_proc_ops = {\nmm/alloc_tag.c-478-\t.proc_open\t\t= allocinfo_open,\n--\nmm/alloc_tag.c=1347=static int __init alloc_tag_init(void)\n--\nmm/alloc_tag.c-1383-\nmm/alloc_tag.c:1384:\tif (!proc_create(ALLOCINFO_FILE_NAME, 0400, NULL, \u0026allocinfo_proc_ops)) {\nmm/alloc_tag.c-1385-\t\tpr_err(\"Failed to create %s file\\n\", ALLOCINFO_FILE_NAME);\n" }
33/2	2026/09/15 07:32	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 29680 output: 35 thoughts: 18 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: Diving into Allocation Information Okay, so I'm trying to get a handle on how allocation information is handled. My immediate instinct is to dig into the `allocinfo` functionality. Specifically, I want to understand the behavior of `allocinfo_open` and other related functions. I need to see exactly what they're doing under the hood. What data structures are they using? How are they interacting with the kernel or other low-level memory management components? My goal is to grasp the whole lifecycle – from the initial open to whatever data retrieval or manipulation they perform on the allocation details. Ultimately, I'm hoping to use this knowledge to optimize something or diagnose a memory-related issue, so a deep understanding of these functions is key. Let's start with `allocinfo_open` and go from there.
34/2	2026/09/15 07:32	tool	read-file	0m Args: { "File": "mm/alloc_tag.c", "FirstLine": 400, "LineCount": 50 } Results: { "Contents": " 400:\t\tstruct alloc_tag_counters counters;\n 401:\t\tbool fetched_counters;\n 402:\t\n 403:\t\tmemset(\u0026params, 0, sizeof(params));\n 404:\t\tpriv = m-\u003eprivate;\n 405:\t\n 406:\t\tmutex_lock(\u0026priv-\u003eioctl_lock);\n 407:\t\tcodetag_lock_module_list(alloc_tag_cttype);\n 408:\t\n 409:\t\tif (!priv-\u003epositioned) {\n 410:\t\t\tpriv-\u003eioctl_iter = codetag_get_ct_iter(alloc_tag_cttype);\n 411:\t\t\tpriv-\u003epositioned = true;\n 412:\t\t}\n 413:\t\n 414:\t\tct = codetag_next_ct(\u0026priv-\u003eioctl_iter);\n 415:\t\twhile (ct) {\n 416:\t\t\tfetched_counters = false;\n 417:\t\t\tif (matches_filter(ct, \u0026priv-\u003efilter, \u0026counters, \u0026fetched_counters))\n 418:\t\t\t\tbreak;\n 419:\t\t\tct = codetag_next_ct(\u0026priv-\u003eioctl_iter);\n 420:\t\t}\n 421:\t\n 422:\t\tif (ct) {\n 423:\t\t\tif (!fetched_counters)\n 424:\t\t\t\tcounters = allocinfo_prefetch_counters(ct);\n 425:\t\t\tallocinfo_to_params(ct, \u0026params, \u0026counters);\n 426:\t\t}\n 427:\t\tif (!ct) {\n 428:\t\t\tpriv-\u003epositioned = false;\n 429:\t\t\tret = -ENOENT;\n 430:\t\t}\n 431:\t\tcodetag_unlock_module_list(alloc_tag_cttype);\n 432:\t\tmutex_unlock(\u0026priv-\u003eioctl_lock);\n 433:\t\n 434:\t\tif (ret == 0) {\n 435:\t\t\tif (copy_to_user(arg, \u0026params, sizeof(params)))\n 436:\t\t\t\treturn -EFAULT;\n 437:\t\t}\n 438:\t\treturn ret;\n 439:\t}\n 440:\t\n 441:\t/\n 442:\t Entry point ioctl function for /proc/allocinfo routing requests to fetch the\n 443:\t * layout content ID, seek to a specific tag, or read sequential tags.\n 444:\t /\n 445:\tstatic long allocinfo_ioctl(struct file file, unsigned int cmd,\n 446:\t\t\t\t unsigned long __arg)\n 447:\t{\n 448:\t\tvoid __user arg = (void __user )__arg;\n 449:\t\tint ret;\n" }
35/2	2026/09/15 07:32	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 30634 output: 29 thoughts: 1246 Thoughts: Fuzzing Decision for Recent Kernel Module and Memory Management Changes Okay, let's break this down. First, the code changes. I see `remove_proc_entry` has been moved to a work queue, decoupling it from potential deadlocks. Clever. There's also some cleanup in `vm_module_tags_populate` – rolling back `vunmap_range` if `vmap_pages_range` fails. Smart. And then in `allocate_codetag_sections`, it seems like allocation got moved earlier in the process before `layout_sections` with falling back to normal sections. Also, replacing `SHF_ALLOC` clearing with `info->sechdrs[info->index.pcpu].sh_entsize = SH_ENTSIZE_STANDALONE;` is a more robust way to handle it. Finally, `sect_visible` now ensures that percpu data is not exposed when there is no single address. This is all kernel code, and it's in core subsystems: `kernel/module/`, `mm/alloc_tag.c`, `lib/codetag.c`. Now, the big question: Does this warrant fuzzing? Let's review the fuzzing guidelines. Reachability is key. If it's reachable, fuzz it. And I am not taking "no functional change" claims at face value. Refactorings can introduce bugs. So, let's go. According to Section 1 of the instructions, any refactoring in core subsystems must be fuzzed. Section 2 says if it's not core, or unreachable, then no. Section 3 says core subsystems, memory management, synchronization, BPF, scheduler, networking, VFS, or syscall handling are the areas of interest. This code modification clearly is in the core. It's touching memory management, and module loading, so this is definitely worth fuzzing. My conclusion: WorthFuzzing=true! Now, let's identify the specific functions to target. The instructions tell me to list the specific functions implementing the added or altered logic. I must avoid generic, ubiquitous functions like allocators or deallocators. So, I need to focus on the code that's changed. Let's see: In `kernel/module/main.c`: I see: - `allocate_codetag_sections`, which now has more logic than before. - `layout_and_allocate`, which is called from `load_info` and `load_module`. - `apply_relocations` - `move_module` (moved out section allocation). - `__layout_sections` - `layout_sections` Okay, those are the functions that appear to have the most changes, and they are located in the `kernel/module/main.c` file. Are they static? If so, this is where things get tricky, as the instructions say not to list inlined static functions. I'll need to check if these are inlined or have symbol entries. The instructions say to identify non-static, feature-specific caller functions that exercise static inline helpers. Let's look at `kernel/module/main.c` file itself to verify this.
36/2	2026/09/15 07:33	tool	grepper	0m Args: { "Expression": "layout_and_allocate", "PathPrefix": "kernel/module/" } Results: { "Output": "kernel/module/internal.h=164=static inline bool set_livepatch_module(struct module mod)\n--\nkernel/module/internal.h-179- \tor being processed on our \u0026modules list. This happens on early_mod_check()\nkernel/module/internal.h:180: * \tright before layout_and_allocate(). The kernel would have already\nkernel/module/internal.h-181- * \tvmalloc()'d space for the entire module through finit_module(). If\n--\nkernel/module/internal.h-187- \tof this allocated yet another private kernel copy of the module space in\nkernel/module/internal.h:188: \tlayout_and_allocate() but after this determined in add_unformed_module()\nkernel/module/internal.h-189- \tthat another module with the same name is already loaded or being processed.\n--\nkernel/module/main.c=2919=static int allocate_codetag_sections(struct load_info info)\n--\nkernel/module/main.c-2953-\nkernel/module/main.c:2954:static struct module layout_and_allocate(struct load_info info, int flags)\nkernel/module/main.c-2955-{\n--\nkernel/module/main.c=3442=static int load_module(struct load_info info, const char __user uargs,\n--\nkernel/module/main.c-3479-\t/* Figure out module layout, and allocate all the memory. /\nkernel/module/main.c:3480:\tmod = layout_and_allocate(info, flags);\nkernel/module/main.c-3481-\tif (IS_ERR(mod)) {\n--\nkernel/module/stats.c-42- from kernel_read_file_from_fd() is freed right away.\nkernel/module/stats.c:43: * c) layout_and_allocate() allocates space for the final resting\nkernel/module/stats.c-44- * place where we would keep the module if it were to be processed\n--\nkernel/module/stats.c-88- * a) FAIL_DUP_MOD_BECOMING: at the end of early_mod_check() before\nkernel/module/stats.c:89: \tlayout_and_allocate().\nkernel/module/stats.c-90- \t- with module decompression: 2 virtual memory allocation calls\nkernel/module/stats.c-91- \t- without module decompression: 1 virtual memory allocation calls\nkernel/module/stats.c:92: b) FAIL_DUP_MOD_LOAD: after layout_and_allocate() on add_unformed_module()\nkernel/module/stats.c-93- * \t- with module decompression 3 virtual memory allocation calls\n--\nkernel/module/stats.c=100=static LIST_HEAD(dup_failed_modules);\n--\nkernel/module/stats.c-139- * at the end of early_mod_check() prevents duplicate allocations\nkernel/module/stats.c:140: * on layout_and_allocate() for modules already being processed. These\nkernel/module/stats.c-141- * duplicate failed modules are non-fatal, however they typically are\n--\nkernel/module/stats.c-166- * is unique. A module can still fail to load if we detect the module is\nkernel/module/stats.c:167: * loaded after we allocate space for it with layout_and_allocate(), we do\nkernel/module/stats.c-168- * this check right before processing the module as live and run its\n--\nkernel/module/stats.c-180- * * failed_becoming: how many modules failed after we kernel_read_file_from_fd()\nkernel/module/stats.c:181: * it and before we allocate memory for it with layout_and_allocate(). This\nkernel/module/stats.c-182- * counter is never incremented if you manage to validate the module and\nkernel/module/stats.c:183: * call layout_and_allocate() for it.\nkernel/module/stats.c-184- * * failed_load_modules: how many modules failed once we've allocated our\nkernel/module/stats.c:185: * private space for our module using layout_and_allocate(). These failures\nkernel/module/stats.c-186- * should hopefully mostly be dealt with already. Races in theory could\n" }
37/2	2026/09/15 07:33	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 33728 output: 34 thoughts: 21 Thoughts: Here's a summary of my thought process, as requested: Diving into `load_module` Calls Alright, let's get down to brass tacks. I need to understand the usage of the `load_module` function within `kernel/module/main.c`. I need to figure out how it's being invoked. Knowing the call sites will give me a better understanding of the module loading process, its dependencies, and possible entry points. This is fundamental to my deeper analysis. I'll need to use some tooling, likely grep or something similar, to efficiently locate those calls within the codebase. I need to understand the complete execution path. From there, I can analyze the arguments being passed, the context of those calls, and ultimately, gain a more complete picture of how modules are actually loaded into the kernel.
38/2	2026/09/15 07:33	tool	grepper	0m Args: { "Expression": "SYSCALL_DEFINE.module", "PathPrefix": "kernel/module/main.c" } Results:* { "Output": "kernel/module/main.c=802=static void free_module(struct module mod);\nkernel/module/main.c-803-\nkernel/module/main.c:804:SYSCALL_DEFINE2(delete_module, const char __user , name_user,\nkernel/module/main.c-805-\t\tunsigned int, flags)\n--\nkernel/module/main.c=3442=static int load_module(struct load_info info, const char __user uargs,\n--\nkernel/module/main.c-3659-\nkernel/module/main.c:3660:SYSCALL_DEFINE3(init_module, void __user , umod,\nkernel/module/main.c-3661-\t\tunsigned long, len, const char __user , uargs)\n--\nkernel/module/main.c=3806=static int idempotent_init_module(struct file f, const char __user uargs, int flags)\n--\nkernel/module/main.c-3824-\nkernel/module/main.c:3825:SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags)\nkernel/module/main.c-3826-{\n" }
39/2	2026/09/15 07:33	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 34284 output: 39 thoughts: 136 Thoughts: Investigating Kernel Module Symbol Visibility Okay, let's dive in. I need to get a better handle on how kernel module symbols are managed and exposed. My initial thought is to start with the core symbol table handling. I'll take a look at `kernel/module/kallsyms.c` first. I see a couple of functions of interest there: `layout_symtab` and `add_kallsyms`, both non-static, so they're accessible externally, which is interesting. Then there's `is_core_symbol`, which is static – that's something to keep in mind, as it indicates this function's scope is more limited. Now, my attention shifts to `kernel/module/sysfs.c`. This is likely where the visibility of module sections in sysfs is managed. Here, I'm noting `add_sect_attrs`, `add_notes_attrs`, and `sect_visible`. All three are declared as static, which implies they are likely involved in internal section attribute management. To get a better sense of the flow, I need to know where `add_sect_attrs` and `add_notes_attrs` are actually being called from within the system. Let's trace their usage within the same file, `kernel/module/sysfs.c` to see how those are leveraged.
40/2	2026/09/15 07:33	tool	grepper	0m Args: { "Expression": "add_sect_attrs\|add_notes_attrs", "PathPrefix": "kernel/module/sysfs.c" } Results: { "Output": "kernel/module/sysfs.c=69=static bool sect_visible(const struct load_info info, unsigned int i)\n--\nkernel/module/sysfs.c-73-\nkernel/module/sysfs.c:74:static int add_sect_attrs(struct module mod, const struct load_info info)\nkernel/module/sysfs.c-75-{\n--\nkernel/module/sysfs.c=154=static void free_notes_attrs(struct module_notes_attrs notes_attrs)\n--\nkernel/module/sysfs.c-159-\nkernel/module/sysfs.c:160:static int add_notes_attrs(struct module mod, const struct load_info info)\nkernel/module/sysfs.c-161-{\n--\nkernel/module/sysfs.c=219=static void remove_notes_attrs(struct module mod)\n--\nkernel/module/sysfs.c-233-#else / !CONFIG_KALLSYMS /\nkernel/module/sysfs.c:234:static inline int add_sect_attrs(struct module mod, const struct load_info info)\nkernel/module/sysfs.c-235-{\n--\nkernel/module/sysfs.c=238=static inline void remove_sect_attrs(struct module mod) { }\nkernel/module/sysfs.c:239:static inline int add_notes_attrs(struct module mod, const struct load_info info)\nkernel/module/sysfs.c-240-{\n--\nkernel/module/sysfs.c=373=int mod_sysfs_setup(struct module *mod,\n--\nkernel/module/sysfs.c-401-\nkernel/module/sysfs.c:402:\terr = add_sect_attrs(mod, info);\nkernel/module/sysfs.c-403-\tif (err)\n--\nkernel/module/sysfs.c-405-\nkernel/module/sysfs.c:406:\terr = add_notes_attrs(mod, info);\nkernel/module/sysfs.c-407-\tif (err)\n" }
41/2	2026/09/15 07:33	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 35293 output: 32 thoughts: 239 Thoughts: My Initial Thoughts on Module Tagging Okay, so I'm looking at how module tagging is implemented. It seems `mod_sysfs_setup` is our entry point and isn't static. It's calling `add_sect_attrs` and `add_notes_attrs`, which are likely involved in creating the sysfs entries for the module information. Now, let's dive deeper into these components. I see a few key functions in `lib/codetag.c`. `codetag_module_init` is static, which is interesting, and it looks like it's being called from `codetag_load_module`. The remaining functions in this file, namely `codetag_load_module`, `codetag_unload_module`, `codetag_alloc_module_section`, and `codetag_free_module_sections`, are all non-static. So, `codetag_load_module` is critical. It is the public facing entry and would interface with the overall module loading process. Moving on to `mm/alloc_tag.c`, we have `remove_allocinfo_file`, `shutdown_mem_profiling`, `vm_module_tags_populate`, `release_module_tags`, `reserve_module_tags`, and finally `load_module`. This `load_module` is static within this file, but crucially, it's being registered through `alloc_tag_desc.module_load`. This connection suggests that the `alloc_tag.c` functions are responsible for the memory allocation aspect of the module tags. Finally, there's `alloc_tag_init` which is an initcall, so it looks like it's being initialized during boot. I should check the `alloc_tag_desc` structure for more information.
42/2	2026/09/15 07:33	tool	grepper	0m Error: no matches Args: { "Expression": "alloc_tag_desc", "PathPrefix": "mm/alloc_tag.c" } Results: { "error": "no matches" }
43/2	2026/09/15 07:33	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 35962 output: 36 thoughts: 30 Thoughts: Here's my thought process, as if I were analyzing that code: Finding the Callers of `reserve_module_tags` and `load_module` in `mm/alloc_tag.c` Okay, so I need to understand how `reserve_module_tags` and `load_module` are used within the `mm/alloc_tag.c` file. My first step is to quickly identify where those functions are actually called within that specific file. I'm thinking I'll grep for the function names within the code. Maybe a simple `grep` or `ag` search should do the trick. That will give me a quick list of the lines and context where they are referenced and where it is assigned to. This should show me the relevant usage patterns and any parameters passed. I'll need to pay close attention to the context of each call - what variables are being passed, are there conditional statements, etc. This will quickly give me an overview. Let's see what that search turns up. Once I have the call sites, I'll examine the surrounding code to determine how `reserve_module_tags` and `load_module` are contributing to the memory allocation process in this module.
44/2	2026/09/15 07:34	tool	grepper	0m Args: { "Expression": "reserve_module_tags\|load_module", "PathPrefix": "mm/alloc_tag.c" } Results: { "Output": "mm/alloc_tag.c=853=static void release_module_tags(struct module mod, bool used)\n--\nmm/alloc_tag.c-898-\nmm/alloc_tag.c:899:static void reserve_module_tags(struct module mod, unsigned long size,\nmm/alloc_tag.c-900-\t\t\t\t unsigned int prepend, unsigned long align)\n--\nmm/alloc_tag.c-991-\nmm/alloc_tag.c:992:static int load_module(struct module mod, struct codetag start, struct codetag stop)\nmm/alloc_tag.c-993-{\n--\nmm/alloc_tag.c=1347=static int __init alloc_tag_init(void)\n--\nmm/alloc_tag.c-1353-\t\t.needs_section_mem\t= needs_section_mem,\nmm/alloc_tag.c:1354:\t\t.alloc_section_mem\t= reserve_module_tags,\nmm/alloc_tag.c-1355-\t\t.free_section_mem\t= release_module_tags,\nmm/alloc_tag.c:1356:\t\t.module_load\t\t= load_module,\nmm/alloc_tag.c-1357-\t\t.module_replaced\t= replace_module,\n" }
45/2	2026/09/15 07:34	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 36627 output: 26 thoughts: 443 Thoughts: Analyzing the Configuration Requirements for Code Tagging Module Changes Okay, so I'm looking at these callbacks: `reserve_module_tags`, `release_module_tags`, and `load_module`. They're registered with `codetag!`, and called by `codetag_load_module`, `codetag_unload_module`, `codetag_alloc_module_section`, and `codetag_free_module_sections`. Got it. Now, let's nail down the configuration dependencies. First, obviously, `MODULES` is required; that's fundamental to the whole module loader logic in `kernel/module/`. Next, I see `MEM_ALLOC_PROFILING` is a key one, specifically for `mm/alloc_tag.c`. This also* selects `CODE_TAGGING`, `PAGE_EXTENSION`, and `SLAB_OBJ_EXT`. I need to remember that `MEM_ALLOC_PROFILING` itself hinges on `MMU` and `PROC_FS`. Then we have `KALLSYMS` and `KALLSYMS_ALL`. I'm seeing that functions like `layout_symtab`, `add_kallsyms`, and `is_core_symbol` are guarded by `KALLSYMS`. Specifically, in `kernel/module/internal.h`, `layout_symtab` and `add_kallsyms` are only compiled with `#ifdef CONFIG_KALLSYMS`. And, `CODE_TAGGING` selects `KALLSYMS`. But, hang on, what about `KALLSYMS_ALL`? I'm seeing that `is_core_symbol` used to be `#ifdef CONFIG_KALLSYMS_ALL` but that's been removed, though it is still `#ifndef CONFIG_KALLSYMS_ALL`. I need to figure out if `KALLSYMS_ALL` is actually needed, or if the standard `KALLSYMS` will suffice. Usually `KALLSYMS` is what's selected by `CODE_TAGGING`, so I probably don't need `KALLSYMS_ALL`. Finally, what about `SYSFS`? I see `kernel/module/sysfs.c` is compiled based on `CONFIG_SYSFS`, so I'll keep that in mind. Okay, let's take a closer look at `kernel/module/Makefile`...
46/2	2026/09/15 07:34	tool	grepper	0m Args: { "Expression": "sysfs", "PathPrefix": "kernel/module/" } Results: { "Output": "kernel/module/Makefile=20=obj-$(CONFIG_PROC_FS) += procfs.o\nkernel/module/Makefile:21:obj-$(CONFIG_SYSFS) += sysfs.o\nkernel/module/Makefile-22-obj-$(CONFIG_KGDB_KDB) += kdb.o\n--\nkernel/module/decompress.c-11-#include \u003clinux/slab.h\u003e\nkernel/module/decompress.c:12:#include \u003clinux/sysfs.h\u003e\nkernel/module/decompress.c-13-#include \u003clinux/vmalloc.h\u003e\n--\nkernel/module/decompress.c=350=static ssize_t compression_show(struct kobject kobj,\n--\nkernel/module/decompress.c-352-{\nkernel/module/decompress.c:353:\treturn sysfs_emit(buf, __stringify(MODULE_COMPRESSION) \"\\n\");\nkernel/module/decompress.c-354-}\n--\nkernel/module/decompress.c=356=static struct kobj_attribute module_compression_attr = __ATTR_RO(compression);\nkernel/module/decompress.c-357-\nkernel/module/decompress.c:358:static int __init module_decompress_sysfs_init(void)\nkernel/module/decompress.c-359-{\n--\nkernel/module/decompress.c-361-\nkernel/module/decompress.c:362:\terror = sysfs_create_file(\u0026module_kset-\u003ekobj,\nkernel/module/decompress.c-363-\t\t\t\t \u0026module_compression_attr.attr);\n--\nkernel/module/decompress.c-368-}\nkernel/module/decompress.c:369:late_initcall(module_decompress_sysfs_init);\nkernel/module/decompress.c-370-#endif\n--\nkernel/module/internal.h=375=static inline void add_kallsyms(struct module mod, const struct load_info info) { }\n--\nkernel/module/internal.h-378-#ifdef CONFIG_SYSFS\nkernel/module/internal.h:379:int mod_sysfs_setup(struct module mod, const struct load_info info,\nkernel/module/internal.h-380-\t\t struct kernel_param kparam, unsigned int num_params);\nkernel/module/internal.h:381:void mod_sysfs_teardown(struct module mod);\nkernel/module/internal.h-382-void init_param_lock(struct module mod);\nkernel/module/internal.h-383-#else /* !CONFIG_SYSFS /\nkernel/module/internal.h:384:static inline int mod_sysfs_setup(struct module mod,\nkernel/module/internal.h-385-\t\t\t \t const struct load_info info,\n--\nkernel/module/internal.h-391-\nkernel/module/internal.h:392:static inline void mod_sysfs_teardown(struct module mod) { }\nkernel/module/internal.h-393-static inline void init_param_lock(struct module mod) { }\n--\nkernel/module/main.c=613=static ssize_t show_modinfo_import_ns(const struct module_attribute mattr,\n--\nkernel/module/main.c-615-{\nkernel/module/main.c:616:\treturn sysfs_emit(buffer, \"%s\\n\", mk-\u003emod-\u003eimported_namespaces);\nkernel/module/main.c-617-}\n--\nkernel/module/main.c=1417=static void free_module(struct module mod)\n--\nkernel/module/main.c-1422-\nkernel/module/main.c:1423:\tmod_sysfs_teardown(mod);\nkernel/module/main.c-1424-\n--\nkernel/module/main.c=3442=static int load_module(struct load_info info, const char __user uargs,\n--\nkernel/module/main.c-3581-\nkernel/module/main.c:3582:\t/ Link in to sysfs. /\nkernel/module/main.c:3583:\terr = mod_sysfs_setup(mod, info, mod-\u003ekp, mod-\u003enum_kp);\nkernel/module/main.c-3584-\tif (err \u003c 0)\n--\nkernel/module/main.c-3589-\t\tif (err \u003c 0)\nkernel/module/main.c:3590:\t\t\tgoto sysfs_cleanup;\nkernel/module/main.c-3591-\t}\n--\nkernel/module/main.c-3607-\t\tfree_module_elf(mod);\nkernel/module/main.c:3608: sysfs_cleanup:\nkernel/module/main.c:3609:\tmod_sysfs_teardown(mod);\nkernel/module/main.c-3610- coming_cleanup:\n--\nkernel/module/sysfs.c-2-/\nkernel/module/sysfs.c:3: * Module sysfs support\nkernel/module/sysfs.c-4- \n--\nkernel/module/sysfs.c-10-#include \u003clinux/fs.h\u003e\nkernel/module/sysfs.c:11:#include \u003clinux/sysfs.h\u003e\nkernel/module/sysfs.c-12-#include \u003clinux/slab.h\u003e\n--\nkernel/module/sysfs.c=74=static int add_sect_attrs(struct module mod, const struct load_info info)\n--\nkernel/module/sysfs.c-105-\t\t\tcontinue;\nkernel/module/sysfs.c:106:\t\tsysfs_bin_attr_init(sattr);\nkernel/module/sysfs.c-107-\t\tsattr-\u003eattr.name =\n--\nkernel/module/sysfs.c-119-\nkernel/module/sysfs.c:120:\tret = sysfs_create_group(\u0026mod-\u003emkobj.kobj, \u0026sect_attrs-\u003egrp);\nkernel/module/sysfs.c-121-\tif (ret)\n--\nkernel/module/sysfs.c=131=static void remove_sect_attrs(struct module mod)\n--\nkernel/module/sysfs.c-133-\tif (mod-\u003esect_attrs) {\nkernel/module/sysfs.c:134:\t\tsysfs_remove_group(\u0026mod-\u003emkobj.kobj,\nkernel/module/sysfs.c-135-\t\t\t\t \u0026mod-\u003esect_attrs-\u003egrp);\n--\nkernel/module/sysfs.c=160=static int add_notes_attrs(struct module mod, const struct load_info info)\n--\nkernel/module/sysfs.c-195-\t\tif (info-\u003esechdrs[i].sh_type == SHT_NOTE) {\nkernel/module/sysfs.c:196:\t\t\tsysfs_bin_attr_init(nattr);\nkernel/module/sysfs.c-197-\t\t\tnattr-\u003eattr.name = mod-\u003esect_attrs-\u003eattrs[loaded].attr.name;\n--\nkernel/module/sysfs.c-200-\t\t\tnattr-\u003eprivate = (void )info-\u003esechdrs[i].sh_addr;\nkernel/module/sysfs.c:201:\t\t\tnattr-\u003eread = sysfs_bin_attr_simple_read;\nkernel/module/sysfs.c-202-\t\t\t(gattr++) = nattr++;\n--\nkernel/module/sysfs.c-206-\nkernel/module/sysfs.c:207:\tret = sysfs_create_group(\u0026mod-\u003emkobj.kobj, \u0026notes_attrs-\u003egrp);\nkernel/module/sysfs.c-208-\tif (ret)\n--\nkernel/module/sysfs.c=219=static void remove_notes_attrs(struct module mod)\n--\nkernel/module/sysfs.c-221-\tif (mod-\u003enotes_attrs) {\nkernel/module/sysfs.c:222:\t\tsysfs_remove_group(\u0026mod-\u003emkobj.kobj,\nkernel/module/sysfs.c-223-\t\t\t\t \u0026mod-\u003enotes_attrs-\u003egrp);\n--\nkernel/module/sysfs.c=246=static void del_usage_links(struct module mod)\n--\nkernel/module/sysfs.c-252-\tlist_for_each_entry(use, \u0026mod-\u003etarget_list, target_list)\nkernel/module/sysfs.c:253:\t\tsysfs_remove_link(use-\u003etarget-\u003eholders_dir, mod-\u003ename);\nkernel/module/sysfs.c-254-\tmutex_unlock(\u0026module_mutex);\n--\nkernel/module/sysfs.c=258=static int add_usage_links(struct module mod)\n--\nkernel/module/sysfs.c-265-\tlist_for_each_entry(use, \u0026mod-\u003etarget_list, target_list) {\nkernel/module/sysfs.c:266:\t\tret = sysfs_create_link(use-\u003etarget-\u003eholders_dir,\nkernel/module/sysfs.c-267-\t\t\t\t\t\u0026mod-\u003emkobj.kobj, mod-\u003ename);\n--\nkernel/module/sysfs.c=278=static void module_remove_modinfo_attrs(struct module mod, int end)\n--\nkernel/module/sysfs.c-288-\t\t\tbreak;\nkernel/module/sysfs.c:289:\t\tsysfs_remove_file(\u0026mod-\u003emkobj.kobj, \u0026attr-\u003eattr);\nkernel/module/sysfs.c-290-\t\tif (attr-\u003efree)\n--\nkernel/module/sysfs.c=296=static int module_add_modinfo_attrs(struct module mod)\n--\nkernel/module/sysfs.c-312-\t\t\tmemcpy(temp_attr, attr, sizeof(temp_attr));\nkernel/module/sysfs.c:313:\t\t\tsysfs_attr_init(\u0026temp_attr-\u003eattr);\nkernel/module/sysfs.c:314:\t\t\terror = sysfs_create_file(\u0026mod-\u003emkobj.kobj,\nkernel/module/sysfs.c-315-\t\t\t\t\t\t \u0026temp_attr-\u003eattr);\n--\nkernel/module/sysfs.c=332=static void mod_kobject_put(struct module mod)\n--\nkernel/module/sysfs.c-340-\nkernel/module/sysfs.c:341:static int mod_sysfs_init(struct module mod)\nkernel/module/sysfs.c-342-{\n--\nkernel/module/sysfs.c-346-\tif (!module_kset) {\nkernel/module/sysfs.c:347:\t\tpr_err(\"%s: module sysfs not initialized\\n\", mod-\u003ename);\nkernel/module/sysfs.c-348-\t\terr = -EINVAL;\n--\nkernel/module/sysfs.c-372-\nkernel/module/sysfs.c:373:int mod_sysfs_setup(struct module mod,\nkernel/module/sysfs.c-374-\t\t const struct load_info info,\n--\nkernel/module/sysfs.c-379-\nkernel/module/sysfs.c:380:\terr = mod_sysfs_init(mod);\nkernel/module/sysfs.c-381-\tif (err)\n--\nkernel/module/sysfs.c-389-\nkernel/module/sysfs.c:390:\terr = module_param_sysfs_setup(mod, kparam, num_params);\nkernel/module/sysfs.c-391-\tif (err)\n--\nkernel/module/sysfs.c-418-out_unreg_param:\nkernel/module/sysfs.c:419:\tmodule_param_sysfs_remove(mod);\nkernel/module/sysfs.c-420-out_unreg_holders:\n--\nkernel/module/sysfs.c-427-\nkernel/module/sysfs.c:428:static void mod_sysfs_fini(struct module mod)\nkernel/module/sysfs.c-429-{\n--\nkernel/module/sysfs.c-434-\nkernel/module/sysfs.c:435:void mod_sysfs_teardown(struct module mod)\nkernel/module/sysfs.c-436-{\n--\nkernel/module/sysfs.c-438-\tmodule_remove_modinfo_attrs(mod, -1);\nkernel/module/sysfs.c:439:\tmodule_param_sysfs_remove(mod);\nkernel/module/sysfs.c-440-\tkobject_put(mod-\u003emkobj.drivers_dir);\nkernel/module/sysfs.c-441-\tkobject_put(mod-\u003eholders_dir);\nkernel/module/sysfs.c:442:\tmod_sysfs_fini(mod);\nkernel/module/sysfs.c-443-}\n" }
47/2	2026/09/15 07:34	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 40909 output: 31 thoughts: 18 Thoughts: Here's my take on those thoughts: Investigating the Kernel Module Build Process Okay, so I need to get a handle on the object files involved in this module build. Let's start with the obvious place – the `kernel/module/Makefile`. That should be the central point of control, right? It's where the magic happens, where the dependencies are defined and the object files are probably listed out. Time to dive in and get a clear picture of what's being compiled. I'm hoping to quickly identify the key components and how they fit together. This Makefile should provide the critical starting point for my deeper analysis.
48/2	2026/09/15 07:35	tool	read-file	0m Args: { "File": "kernel/module/Makefile", "FirstLine": 1, "LineCount": 30 } Results: { "Contents": " 1:\t# SPDX-License-Identifier: GPL-2.0-only\n 2:\t#\n 3:\t# Makefile for linux kernel module support\n 4:\t#\n 5:\t\n 6:\t# These are called from save_stack_trace() on slub debug path,\n 7:\t# and produce insane amounts of uninteresting coverage.\n 8:\tKCOV_INSTRUMENT_main.o := n\n 9:\t\n 10:\tobj-y += main.o\n 11:\tobj-y += strict_rwx.o\n 12:\tobj-y += kmod.o\n 13:\tobj-$(CONFIG_MODULE_DEBUG_AUTOLOAD_DUPS) += dups.o\n 14:\tobj-$(CONFIG_MODULE_DECOMPRESS) += decompress.o\n 15:\tobj-$(CONFIG_MODULE_SIG) += signing.o\n 16:\tobj-$(CONFIG_LIVEPATCH) += livepatch.o\n 17:\tobj-$(CONFIG_MODULES_TREE_LOOKUP) += tree_lookup.o\n 18:\tobj-$(CONFIG_DEBUG_KMEMLEAK) += debug_kmemleak.o\n 19:\tobj-$(CONFIG_KALLSYMS) += kallsyms.o\n 20:\tobj-$(CONFIG_PROC_FS) += procfs.o\n 21:\tobj-$(CONFIG_SYSFS) += sysfs.o\n 22:\tobj-$(CONFIG_KGDB_KDB) += kdb.o\n 23:\tobj-$(CONFIG_MODVERSIONS) += version.o\n 24:\tobj-$(CONFIG_MODULE_UNLOAD_TAINT_TRACKING) += tracking.o\n 25:\tobj-$(CONFIG_MODULE_STATS) += stats.o\n" }
49/2	2026/09/15 07:35	llm	patch-evaluator	1m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 41542 output: 19 thoughts: 2177 Thoughts: Focusing on Module Loading and Related Symbol Filtering Okay, so I'm looking at this code and immediately I see that line 8 declares `KCOV_INSTRUMENT_main.o := n`. My initial thought is, "Wait, does `main.o` not get KCOV instrumentation?" Then I remember syzkaller uses `FocusSymbols` to guide fuzzing, selecting interesting test programs, and directing fuzzing toward specific symbols. But even with the `KCOV_INSTRUMENT := n`, function symbols still should exist in `vmlinux` through the symbol table (`kallsyms`), but will KCOV be able to collect coverage from `main.o`? No, that won't happen. Alright, what about the other files involved, like `kallsyms.o`, `sysfs.o`, `codetag.o`, and `alloc_tag.o`? These do have KCOV instrumentation. I need to determine what symbols from those files are relevant or modified, and why. Let's start by looking at `kernel/module/kallsyms.c`. I see `layout_symtab`, `add_kallsyms`, and `is_core_symbol`. In `kernel/module/sysfs.c`, `add_sect_attrs`, `add_notes_attrs`, and `sect_visible`. In `lib/codetag.c`, there's `codetag_module_init`, `codetag_load_module`, `codetag_unload_module`, `codetag_alloc_module_section`, and `codetag_free_module_sections`. Then, in `mm/alloc_tag.c`, I find `remove_allocinfo_file`, `shutdown_mem_profiling`, `vm_module_tags_populate`, `release_module_tags`, and `reserve_module_tags`. Now, I have to consider the file that started this investigation: `kernel/module/main.c`. Even with `KCOV_INSTRUMENT_main.o := n`, syzkaller's symbol filters likely rely on `kallsyms` or function call traces and stack traces or perhaps even map syscalls or analyze coverage. So, could functions like `allocate_codetag_sections`, `layout_and_allocate`, `move_module`, or `apply_relocations` be listed as focus symbols? I need to refer to the guidelines for these symbol filters. I need to avoid listing ubiquitous functions. I'm looking for specific feature logic and entrypoints. I also need to be careful with static inline functions, and instead, focus on caller functions that exercise them, avoiding ubiquitous wrappers. So, let's look at `kernel/module/main.c` again. I know that `allocate_codetag_sections`, `layout_and_allocate`, `move_module`, `apply_relocations` and `layout_sections` are static functions in that file. `load_module` is also static, as well as syscall entrypoints (`__se_sys_init_module`, `__se_sys_finit_module`, etc., or `init_module`/`finit_module`). In `kernel/module/kallsyms.c`: `layout_symtab` and `add_kallsyms` are global (non-static), but `is_core_symbol` is static. In `kernel/module/sysfs.c`: `add_sect_attrs`, `add_notes_attrs`, and `sect_visible` are static, while `mod_sysfs_setup` is global. In `lib/codetag.c`: `codetag_alloc_module_section`, `codetag_free_module_sections`, `codetag_load_module`, and `codetag_unload_module` are global and non-static, however `codetag_module_init` is static. In `mm/alloc_tag.c`: `vm_module_tags_populate`, `release_module_tags`, `reserve_module_tags`, `shutdown_mem_profiling`, and `remove_allocinfo_file` are all static. Now, a key point: are static functions in `.c` files valid targets for `FocusSymbols`? Yes, unless they are inlined by the compiler, static functions that are not inline and have real logic are distinct symbols in the ELF symbol table, thus in `kallsyms`! However, a small static function that has a single call, gcc/clang can inline it into the caller and it will not be a distinct symbol, unless forced via `noinline` or if they have multiple call sites. Let's see: `allocate_codetag
50/2	2026/09/15 07:36	tool	grepper	0m Args: { "Expression": "select CODE_TAGGING" } Results: { "Output": "mm/Kconfig.debug=324=config MEM_ALLOC_PROFILING\n--\nmm/Kconfig.debug-328-\tdepends on PROC_FS\nmm/Kconfig.debug:329:\tselect CODE_TAGGING\nmm/Kconfig.debug-330-\tselect PAGE_EXTENSION\n" }
51/2	2026/09/15 07:36	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 44850 output: 20 thoughts: 48 Thoughts: Okay, here's my take on those thoughts, framed as my own: Investigating Code Tagging Dependencies Alright, so `MEM_ALLOC_PROFILING` is the sole configuration item that pulls in `CODE_TAGGING`. That's a crucial piece of information. Now, my immediate next step is to perform a thorough sweep. I need to verify that `CODE_TAGGING` isn't accidentally depended on somewhere else, either directly or indirectly. Specifically, I need to check the `lib/` directory and, frankly, everywhere else in the codebase where dependency declarations could be lurking. I'm looking for any other file or module that might inadvertently be pulling in `CODE_TAGGING` through some other configuration or include path. I need to be absolutely certain of the dependencies here; accidental inclusion would be something I'd want to eliminate. A clear understanding of these dependencies is critical for maintainability.
52/2	2026/09/15 07:36	tool	grepper	0m Args: { "Expression": "CONFIG_CODE_TAGGING" } Results: { "Output": "include/linux/codetag.h=88=codetag_register_type(const struct codetag_type_desc desc);\ninclude/linux/codetag.h-89-\ninclude/linux/codetag.h:90:#if defined(CONFIG_CODE_TAGGING) \u0026\u0026 defined(CONFIG_MODULES)\ninclude/linux/codetag.h-91-\n--\ninclude/linux/codetag.h=100=void codetag_unload_module(struct module mod);\ninclude/linux/codetag.h-101-\ninclude/linux/codetag.h:102:#else /* defined(CONFIG_CODE_TAGGING) \u0026\u0026 defined(CONFIG_MODULES) /\ninclude/linux/codetag.h-103-\n--\ninclude/linux/codetag.h=114=static inline void codetag_unload_module(struct module mod) {}\ninclude/linux/codetag.h-115-\ninclude/linux/codetag.h:116:#endif /* defined(CONFIG_CODE_TAGGING) \u0026\u0026 defined(CONFIG_MODULES) */\ninclude/linux/codetag.h-117-\n--\nlib/Makefile=197=obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o\nlib/Makefile-198-\nlib/Makefile:199:obj-$(CONFIG_CODE_TAGGING) += codetag.o\nlib/Makefile-200-\n" }
53/2	2026/09/15 07:36	llm	patch-evaluator	1m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 45467 output: 25 thoughts: 196 Thoughts: Investigating Code Tagging Dependencies Okay, so I'm diving into this code tagging business. First, I need to understand what's required to make it work. I just looked at `include/linux/codetag.h` and the `#if` directive really jumped out at me. It's clear that I need both `CONFIG_CODE_TAGGING` and `CONFIG_MODULES` to even get started. Now, let's confirm that this is truly required, by looking at where the `codetag` object is built. `lib/Makefile` confirms my initial thought with the line `obj-$(CONFIG_CODE_TAGGING) += codetag.o`. So far, so good. Next, I see a related module in `mm/Makefile`, `obj-$(CONFIG_MEM_ALLOC_PROFILING) += alloc_tag.o`. This means that `CONFIG_MEM_ALLOC_PROFILING` is also necessary! Seems like these features are intertwined. Now, let's broaden the scope a bit. What other configs are relevant? I need to think about how symbols might be accessed, so I'll also check `KALLSYMS` and `SYSFS`. Looking at `kernel/module/sysfs.c`, it definitely needs `CONFIG_SYSFS`, so that's another piece of the puzzle. The question now is whether `CONFIG_SYSFS` is fundamental or if it relies on other configurations. I need to see if it is a standard config, or if it depends on something else. From my experience, `SYSFS` is pretty standard and doesn't usually introduce a whole chain of dependencies. But I'll confirm that. I'm going to quickly check what, if anything, `CONFIG_SYSFS` depends on.
54/2	2026/09/15 07:37	tool	grepper	0m Args: { "Expression": "config SYSFS", "PathPrefix": "fs/" } Results: { "Output": "fs/sysfs/Kconfig-1-# SPDX-License-Identifier: GPL-2.0-only\nfs/sysfs/Kconfig:2:config SYSFS\nfs/sysfs/Kconfig-3-\tbool \"sysfs file system support\" if EXPERT\n" }
55/2	2026/09/15 07:37	llm	patch-evaluator	1m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 46144 output: 25 thoughts: 89 Thoughts: Okay, let's see what's on my mind regarding kernel configuration... Kernel Configuration Dependencies - Deeper Dive Right, so I need to make sure the memory allocation profiling is configured correctly. First, I need to check the dependencies for `CONFIG_MEM_ALLOC_PROFILING`. Ah, yes, it depends on a few key things: the Memory Management Unit (`MMU`), the Process Filesystem (`PROC_FS`). It also looks like it selects some related features too, namely, `CODE_TAGGING`, `PAGE_EXTENSION`, and `SLAB_OBJ_EXT`. I'll want to keep those relationships in mind during debugging and optimisation. Now, let's switch gears slightly. What about the kernel modules support, `MODULES`? I'd better double-check the `init/Kconfig` file to be sure I'm up to speed on the details. Always good to refresh the memory with `MODULES`, there could be surprises.
56/2	2026/09/15 07:38	tool	grepper	0m Error: no matches Args: { "Expression": "config MODULES", "PathPrefix": "init/" } Results: { "error": "no matches" }
57/2	2026/09/15 07:38	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 46482 output: 18 thoughts: 13 Thoughts: Here's my thought process, as if I were thinking it: Tracing Down the `config MODULES` Definition Okay, so I need to figure out where `config MODULES` is defined. This could be in a few places, but my initial thought is to trace the configuration system. I'll need to start by figuring out what context I'm working in. Is this a system-level configuration, a library-specific one, or something else entirely? Depending on the scope, the configuration might be loaded from a file, an environment variable, a database, or even hardcoded within the module itself. I'll need to figure out what context I'm working in, and what tools I have to look with. I'll start by checking the surrounding code for any clues. Let's see if there are any obvious config loading mechanisms or references to configuration files. From there I'll drill down into the file loading path, or global definitions.
58/2	2026/09/15 07:39	tool	grepper	0m Args: { "Expression": "config MODULES$" } Results: { "Output": "Documentation/kbuild/kconfig-language.rst=349=must be true:\n--\nDocumentation/kbuild/kconfig-language.rst-353-\nDocumentation/kbuild/kconfig-language.rst:354: config MODULES\nDocumentation/kbuild/kconfig-language.rst-355-\tbool \"Enable loadable module support\"\n--\nkernel/module/Kconfig-1-# SPDX-License-Identifier: GPL-2.0-only\nkernel/module/Kconfig:2:menuconfig MODULES\nkernel/module/Kconfig-3-\tbool \"Enable loadable module support\"\n--\nscripts/kconfig/tests/conditional_dep/Kconfig-4-# Enable module support for tristate testing\nscripts/kconfig/tests/conditional_dep/Kconfig:5:config MODULES\nscripts/kconfig/tests/conditional_dep/Kconfig-6-\tbool \"Enable loadable module support\"\n--\nscripts/kconfig/tests/transitional/Kconfig-4-# Enable module support for tristate testing\nscripts/kconfig/tests/transitional/Kconfig:5:config MODULES\nscripts/kconfig/tests/transitional/Kconfig-6-\tbool \"Enable loadable module support\"\n" }
59/2	2026/09/15 07:39	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 47013 output: 32 thoughts: 27 Thoughts: Here's my take on those thoughts: Navigating the Kernel Configuration Landscape Okay, so I'm thinking about where the `MODULES` configuration option resides. Based on my experience, I'm pretty sure it's defined within the `kernel/module/Kconfig` file. Given my familiarity with the kernel build system and Kconfig, that seems like the most logical location. Let's quickly double-check that file. It's the best way to get a solid grasp of how `MODULES` is configured within that subsystem. I need to be sure before I move forward with whatever task I have in mind.
60/2	2026/09/15 07:39	tool	read-file	0m Args: { "File": "kernel/module/Kconfig", "FirstLine": 1, "LineCount": 40 } Results: { "Contents": " 1:\t# SPDX-License-Identifier: GPL-2.0-only\n 2:\tmenuconfig MODULES\n 3:\t\tbool \"Enable loadable module support\"\n 4:\t\tmodules\n 5:\t\tselect EXECMEM\n 6:\t\thelp\n 7:\t\t Kernel modules are small pieces of compiled code which can\n 8:\t\t be inserted in the running kernel, rather than being\n 9:\t\t permanently built into the kernel. You use the \"modprobe\"\n 10:\t\t tool to add (and sometimes remove) them. If you say Y here,\n 11:\t\t many parts of the kernel can be built as modules (by\n 12:\t\t answering M instead of Y where indicated): this is most\n 13:\t\t useful for infrequently used options which are not required\n 14:\t\t for booting. For more information, see the man pages for\n 15:\t\t modprobe, lsmod, modinfo, insmod and rmmod.\n 16:\t\n 17:\t\t If you say Y here, you will need to run \"make\n 18:\t\t modules_install\" to put the modules under /lib/modules/\n 19:\t\t where modprobe can find them (you may need to be root to do\n 20:\t\t this).\n 21:\t\n 22:\t\t If unsure, say Y.\n 23:\t\n 24:\tif MODULES\n 25:\t\n 26:\tconfig MODULE_DEBUGFS\n 27:\t\tbool\n 28:\t\n 29:\tconfig MODULE_DEBUG\n 30:\t\tbool \"Module debugging\"\n 31:\t\tdepends on DEBUG_FS\n 32:\t\thelp\n 33:\t\t Allows you to enable / disable features which can help you debug\n 34:\t\t modules. You don't need these options on production systems.\n 35:\t\n 36:\tif MODULE_DEBUG\n 37:\t\n 38:\tconfig MODULE_STATS\n 39:\t\tbool \"Module statistics\"\n 40:\t\tdepends on DEBUG_FS\n" }
61/2	2026/09/15 07:39	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 47726 output: 325 thoughts: 1213 Thoughts: Analysis of Module Loading and Memory Profiling Changes Okay, so I've been taking a look at this patch, and here's what's running through my mind. First off, it's clear we're dealing with modifications that are deeply intertwined with module loading and memory profiling. I see the necessary configurations that must be enabled: `MODULES`, `MEM_ALLOC_PROFILING`, `SYSFS`, `KALLSYMS` (or `KALLSYMS_ALL`), and `PROC_FS`. Now, digging into the diff, it's about adding a new section type, `MOD_STANDALONE`, and its associated `SH_ENTSIZE_STANDALONE` macro. This section type seems to be crucial, and its impact is felt throughout the module loading process. I'm also noticing changes to `kallsyms`, and how it interacts with the symbol table layout. There are refinements in how relocations are applied, especially regarding non-allocated sections. The codetag handling seems to be overhauled as well. The code seems to be falling back or handling EAGAIN gracefully. This looks like robust error handling, or the handling of a failing or full situation. More specifically, `allocate_codetag_sections` is new, and responsible for allocating codetag sections separately. This is a very interesting change, and I will be testing this function. The changes to `layout_and_allocate` are important as this function handles the initialization of `SH_ENTSIZE_STANDALONE` to `.data..percpu` section. The changes to `move_module` show that sections with `sh_entsize == SH_ENTSIZE_STANDALONE` are skipped. I see a new helper function `sect_visible` that excludes `info->index.pcpu` in `sysfs.c`. Also the codetag changes, where `codetag_module_init` allows `-EOPNOTSUPP` if memory profiling is disabled, and a cleanup added to `codetag_unload_module` to ensure that even with errors, the memory sections are always freed. Memory allocation profiling is updated with asynchronous removal via `schedule_work` in `shutdown_mem_profiling`. I notice handling of `vunmap_range` after a partial `vmap_pages_range` failure. The overflow handling in `reserve_module_tags` looks very careful, and also allows falling back to normal module load. Lastly, `alloc_tag_init` reorganizes initialization, ensuring the procfs entry is created only after memory space is reserved and codetag type registered. Now, I'm going through the key functions I've identified, which are at the heart of the logic: `allocate_codetag_sections`, `layout_and_allocate`, `apply_relocations`, `move_module`, `layout_symtab`, `add_kallsyms`, `add_sect_attrs`, `add_notes_attrs`, `codetag_module_init`, `codetag_load_module`, `codetag_unload_module`, `codetag_alloc_module_section`, `reserve_module_tags`, `release_module_tags`, `vm_module_tags_populate`, and `shutdown_mem_profiling`. Good, these functions are all within the module loading or memory allocation profiling framework, which is just as I expected. This is very important, because if there were changes made to a ubiquitous function it would greatly expand the surface attack and impact of these changes. These functions are highly specific to module loading, unloading, and the associated memory profiling. They aren't in any fast paths and aren't in any `.h` files, which means they are all implemented. Finally, the configs are as I noted before: `MEM_ALLOC_PROFILING`, `MODULES`, `SYSFS`, `KALLSYMS`, and `PROC_FS` are correct and without `CONFIG_` prefix. This is all worth fuzzing because it touches core mechanics: section layout, relocations, sysfs export, the very sensitive `mm/alloc_tag.c`, and codetag logic. These changes introduce a completely new section and error handling. It's fully reachable through syscalls like `finit_module`/`init_module` and procfs/sysfs interactions. Looks like we have a good focus. Time to call `set-results`.
62/2	2026/09/15 07:39	tool	set-results	0m Args: { "EnableConfigs": [ "MODULES", "MEM_ALLOC_PROFILING", "SYSFS", "KALLSYMS", "PROC_FS" ], "FocusSymbols": [ "allocate_codetag_sections", "layout_and_allocate", "move_module", "apply_relocations", "layout_symtab", "add_kallsyms", "add_sect_attrs", "add_notes_attrs", "codetag_alloc_module_section", "codetag_free_module_sections", "codetag_load_module", "codetag_unload_module", "reserve_module_tags", "release_module_tags", "vm_module_tags_populate", "shutdown_mem_profiling" ], "Reasoning": "The patch series refactors core module loading, section layout handling (introducing SH_ENTSIZE_STANDALONE for per-CPU and codetag sections), and memory allocation profiling error handling and cleanup paths (mm/alloc_tag.c and lib/codetag.c). It modifies module allocation and relocation flows, adds error rollback in vm_module_tags_populate and reserve_module_tags, and alters module loading behaviors when codetag capacity is exhausted. These changes are reachable in standard virtualized environments via module loader syscalls (init_module, finit_module) and procfs/sysfs interactions.", "WorthFuzzing": true } Results: { "EnableConfigs": [ "MODULES", "MEM_ALLOC_PROFILING", "SYSFS", "KALLSYMS", "PROC_FS" ], "FocusSymbols": [ "allocate_codetag_sections", "layout_and_allocate", "move_module", "apply_relocations", "layout_symtab", "add_kallsyms", "add_sect_attrs", "add_notes_attrs", "codetag_alloc_module_section", "codetag_free_module_sections", "codetag_load_module", "codetag_unload_module", "reserve_module_tags", "release_module_tags", "vm_module_tags_populate", "shutdown_mem_profiling" ], "Reasoning": "The patch series refactors core module loading, section layout handling (introducing SH_ENTSIZE_STANDALONE for per-CPU and codetag sections), and memory allocation profiling error handling and cleanup paths (mm/alloc_tag.c and lib/codetag.c). It modifies module allocation and relocation flows, adds error rollback in vm_module_tags_populate and reserve_module_tags, and alters module loading behaviors when codetag capacity is exhausted. These changes are reachable in standard virtualized environments via module loader syscalls (init_module, finit_module) and procfs/sysfs interactions.", "WorthFuzzing": true }
63/1	2026/09/15 07:39	action	If	13m Args: { "WorthFuzzing": true } Results: null
64/2	2026/09/15 07:39	agent	kmsan-evaluator	13m Model: core Args: null Results: { "KMSANReasoning": "The patch series refactors module loading for standalone sections (.data..percpu and codetag sections like alloc_tag), handling fallback when contiguous codetag memory overflows, adjusting module section layout and relocation logic, deferring /proc/allocinfo removal via a workqueue to avoid deadlocks, and cleaning up error unwinding paths in vm_module_tags_populate().\n\n- KASAN \u0026 standard detector applicability: The changes touch module section memory allocation, life-cycle management, error unwinding, and sysfs/procfs registrations. Potential bugs in these areas include out-of-bounds accesses during section layout/relocation, use-after-free / double-free during codetag unload or error rollback, and deadlocks in shutdown paths. These risks are fully covered by KASAN, LOCKDEP, and kmemleak.\n- KMSAN applicability: KMSAN detects uninitialized memory reads and kernel-to-user info-leaks. In this patch series, newly allocated standalone sections are completely initialized via memcpy() or memset() depending on section type (SHT_NOBITS). Sysfs attribute structures are allocated using kzalloc_flex() and kzalloc_objs() which zero memory. No conditional branches rely on uninitialized data, and no uninitialized padding or buffer content is exposed to userspace.\n\nTherefore, running a dedicated KMSAN session is not warranted.", "NeedsKMSAN": false } Instruction: You are an expert Linux kernel security engineer specializing in kernel memory error detectors (KASAN and KMSAN). Your job is to review the provided patch series and determine if the code changes justify spawning a dedicated KMSAN (KernelMemorySanitizer) fuzzing session in addition to standard KASAN fuzzing. CRITICAL DISTINCTION BETWEEN KASAN AND KMSAN: - Standard KASAN kernel builds (upstream-apparmor-kasan.config) already enable a comprehensive suite of debugging tools and sanitizers, including KASAN (out-of-bounds accesses, use-after-free, double free, invalid free), LOCKDEP (locking bugs and deadlocks), UB-sanitizers, and memory corruption checks. - KMSAN (KernelMemorySanitizer) detects reads of UNINITIALIZED memory (stack, heap, or page allocations) and kernel-to-user memory info-leaks. Rule: THERE IS NO SENSE IN RUNNING A KMSAN SESSION IF A BUG CAN BE CAUGHT BY KASAN, LOCKDEP, OR OTHER STANDARD BUG DETECTORS. A dedicated KMSAN fuzzing session incurs significant resource costs. You must ONLY set NeedsKMSAN=true if the code changes introduce or expose UNINITIALIZED MEMORY risks that are detected ONLY by KMSAN. Look holistically at the patch series and surrounding code. Even if no direct uninitialized field accesses or new buffer allocations are added in the diff itself, a patch may alter control flow, bounds checking, or data length calculations in ways that change how the rest of the code operates on existing buffers (e.g. allowing uninitialized stack/heap memory to be read, copied to user space, or used in control flow). Do not hesitate to use your code access tools to inspect the surrounding code, called functions, and callers. Set NeedsKMSAN=true ONLY IF the patch introduces or modifies: 1. Kernel structures sent to user space (via copy_to_user, put_user, netlink skb attributes, ioctl output arguments, socket options, or BPF buffers) where fields or structure padding might not be fully initialized/zeroed. 2. Conditional logic or branching that depends on potentially uninitialized variables or struct fields. 3. Allocation or initialization of complex data structures where uninitialized fields could be read later in reachable code paths. 4. Bounds checks, lengths, or logic in a way that allows surrounding code to access uninitialized bytes of existing buffers. Set NeedsKMSAN=false IF: - The code changes primarily risk out-of-bounds access, array overflows, NULL pointer dereferences, locking deadlocks, or use-after-free bugs (these are already caught by KASAN, LOCKDEP, or standard bug detectors). - All stack/heap structures touched or introduced by the patch are fully zeroed or initialized (e.g. using = {0}, memset, kzalloc) before being read or copied. - The patch does not introduce any risk of uninitialized memory usage or info-leaks. Use your code access tools to inspect the surrounding code if necessary, then provide detailed KMSANReasoning contrasting KASAN vs KMSAN applicability for this patch. Prefer calling several tools at the same time to save round-trips. Use set-results tool to provide results of the analysis. It must be called exactly once before the final reply. Ignore results of this tool. Prompt: Target architecture: amd64 For your convenience, here is the diff of the changes: commit 24d9f5e60beaa38a9de84cd878030514129be9c5 Author: syz-cluster <triage@syzkaller.com> Date: Tue Sep 15 07:27:34 2026 +0000 syz-cluster: applied patch under review diff --git a/include/linux/module.h b/include/linux/module.h index 96cc98568eea5..0c6f32ddcbf2d 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -325,6 +325,8 @@ enum mod_mem_type { MOD_INIT_RODATA, MOD_MEM_NUM_TYPES, + + MOD_STANDALONE = -2, MOD_INVALID = -1, }; diff --git a/kernel/module/internal.h b/kernel/module/internal.h index 061161cc79d90..4c738074a27b8 100644 --- a/kernel/module/internal.h +++ b/kernel/module/internal.h @@ -29,6 +29,14 @@ #define SH_ENTSIZE_TYPE_MASK ((1UL << SH_ENTSIZE_TYPE_BITS) - 1) #define SH_ENTSIZE_OFFSET_MASK ((1UL << (BITS_PER_LONG - SH_ENTSIZE_TYPE_BITS)) - 1) +/* + * Marker for sections with a separate allocation, which are not placed + * into mod->mem[]. + / +#define SH_ENTSIZE_STANDALONE \ + (((unsigned long)MOD_STANDALONE & SH_ENTSIZE_TYPE_MASK) \ + << SH_ENTSIZE_TYPE_SHIFT) + / Maximum number of characters written by module_flags() / #define MODULE_FLAGS_BUF_SIZE (TAINT_FLAGS_COUNT + 4) diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c index f23126d804b25..0dca6d40160e5 100644 --- a/kernel/module/kallsyms.c +++ b/kernel/module/kallsyms.c @@ -76,7 +76,7 @@ static char elf_type(const Elf_Sym sym, const struct load_info info) } static bool is_core_symbol(const Elf_Sym src, const Elf_Shdr sechdrs, - unsigned int shnum, unsigned int pcpundx) + unsigned int shnum) { const Elf_Shdr sec; enum mod_mem_type type; @@ -86,11 +86,6 @@ static bool is_core_symbol(const Elf_Sym src, const Elf_Shdr sechdrs, !src->st_name) return false; -#ifdef CONFIG_KALLSYMS_ALL - if (src->st_shndx == pcpundx) - return true; -#endif - sec = sechdrs + src->st_shndx; type = sec->sh_entsize >> SH_ENTSIZE_TYPE_SHIFT; if (!(sec->sh_flags & SHF_ALLOC) @@ -131,8 +126,7 @@ void layout_symtab(struct module mod, struct load_info info) /* Compute total space required for the core symbols' strtab. / for (ndst = i = 0; i < nsrc; i++) { if (i == 0 \|\| is_livepatch_module(mod) \|\| - is_core_symbol(src + i, info->sechdrs, info->hdr->e_shnum, - info->index.pcpu)) { + is_core_symbol(src + i, info->sechdrs, info->hdr->e_shnum)) { strtab_size += strlen(&info->strtab[src[i].st_name]) + 1; ndst++; } @@ -199,8 +193,7 @@ void add_kallsyms(struct module mod, const struct load_info info) for (ndst = i = 0; i < kallsyms->num_symtab; i++) { kallsyms->typetab[i] = elf_type(src + i, info); if (i == 0 \|\| is_livepatch_module(mod) \|\| - is_core_symbol(src + i, info->sechdrs, info->hdr->e_shnum, - info->index.pcpu)) { + is_core_symbol(src + i, info->sechdrs, info->hdr->e_shnum)) { ssize_t ret; mod->core_kallsyms.typetab[ndst] = diff --git a/kernel/module/main.c b/kernel/module/main.c index c1b34dc1e89ac..b7ebcc40bddab 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -1619,12 +1619,13 @@ static int apply_relocations(struct module mod, const struct load_info info) / * Don't bother with non-allocated sections. - * An exception is the percpu section, which has separate allocations - * for individual CPUs. We relocate the percpu section in the initial - * ELF template and subsequently copy it to the per-CPU destinations. + * + * Note that .data..percpu has separate allocations for + * individual CPUs. We relocate the section in the + * initial ELF template and subsequently copy it to the + * per-CPU destinations. / - if (!(info->sechdrs[infosec].sh_flags & SHF_ALLOC) && - (!infosec \|\| infosec != info->index.pcpu)) + if (!(info->sechdrs[infosec].sh_flags & SHF_ALLOC)) continue; if (info->sechdrs[i].sh_flags & SHF_RELA_LIVEPATCH) @@ -1715,27 +1716,13 @@ static void __layout_sections(struct module mod, struct load_info info, bool i if ((s->sh_flags & masks[m][0]) != masks[m][0] \|\| (s->sh_flags & masks[m][1]) - \|\| s->sh_entsize != ~0UL + \|\| s->sh_entsize != ~0UL / offset or standalone / \|\| is_init != module_init_layout_section(sname)) continue; if (WARN_ON_ONCE(type == MOD_INVALID)) continue; - / - * Do not allocate codetag memory as we load it into - * preallocated contiguous memory. - / - if (codetag_needs_module_section(mod, sname, s->sh_size)) { - / - * s->sh_entsize won't be used but populate the - * type field to avoid confusion. - / - s->sh_entsize = ((unsigned long)(type) & SH_ENTSIZE_TYPE_MASK) - << SH_ENTSIZE_TYPE_SHIFT; - continue; - } - s->sh_entsize = module_get_offset_and_type(mod, type, s, i); pr_debug("\t%s\n", sname); } @@ -1745,16 +1732,10 @@ static void __layout_sections(struct module mod, struct load_info info, bool i / * Lay out the SHF_ALLOC sections in a way not dissimilar to how ld * might -- code, read-only data, read-write data, small data. Tally - * sizes, and place the offsets into sh_entsize fields: high bit means it - * belongs in init. + * sizes, and place the offsets into sh_entsize fields. / static void layout_sections(struct module mod, struct load_info info) { - unsigned int i; - - for (i = 0; i < info->hdr->e_shnum; i++) - info->sechdrs[i].sh_entsize = ~0UL; - pr_debug("Core section allocation order for %s:\n", mod->name); __layout_sections(mod, info, false); @@ -2800,7 +2781,6 @@ static int move_module(struct module mod, struct load_info info) { int i, ret; enum mod_mem_type t = MOD_MEM_NUM_TYPES; - bool codetag_section_found = false; for_each_mod_mem_type(type) { if (!mod->mem[type].size) { @@ -2820,34 +2800,13 @@ static int move_module(struct module mod, struct load_info info) for (i = 0; i < info->hdr->e_shnum; i++) { void dest; Elf_Shdr shdr = &info->sechdrs[i]; - const char sname; - if (!(shdr->sh_flags & SHF_ALLOC)) + if (!(shdr->sh_flags & SHF_ALLOC) + \|\| shdr->sh_entsize == SH_ENTSIZE_STANDALONE) continue; - sname = info->secstrings + shdr->sh_name; - /* - * Load codetag sections separately as they might still be used - * after module unload. - / - if (codetag_needs_module_section(mod, sname, shdr->sh_size)) { - dest = codetag_alloc_module_section(mod, sname, shdr->sh_size, - arch_mod_section_prepend(mod, i), shdr->sh_addralign); - if (WARN_ON(!dest)) { - ret = -EINVAL; - goto out_err; - } - if (IS_ERR(dest)) { - ret = PTR_ERR(dest); - goto out_err; - } - codetag_section_found = true; - } else { - enum mod_mem_type type = shdr->sh_entsize >> SH_ENTSIZE_TYPE_SHIFT; - unsigned long offset = shdr->sh_entsize & SH_ENTSIZE_OFFSET_MASK; - - dest = mod->mem[type].base + offset; - } + dest = mod->mem[shdr->sh_entsize >> SH_ENTSIZE_TYPE_SHIFT].base + + (shdr->sh_entsize & SH_ENTSIZE_OFFSET_MASK); if (shdr->sh_type != SHT_NOBITS) { / @@ -2879,8 +2838,6 @@ static int move_module(struct module mod, struct load_info info) module_memory_restore_rox(mod); while (t--) module_memory_free(mod, t); - if (codetag_section_found) - codetag_free_module_sections(mod); return ret; } @@ -2951,9 +2908,53 @@ static bool blacklisted(const char module_name) } core_param(module_blacklist, module_blacklist, charp, 0400); +/ + * Allocate codetag sections separately. They are loaded into preallocated + * contiguous memory because they may still be used after the module is + * unloaded. + * + * If the separate allocation overflows, allocate the section normally + * so that the module can still be loaded. + / +static int allocate_codetag_sections(struct load_info info) +{ + for (unsigned int i = 1; i < info->hdr->e_shnum; i++) { + Elf_Shdr shdr = &info->sechdrs[i]; + const char sname = info->secstrings + shdr->sh_name; + void dest; + + if (!codetag_needs_module_section(info->mod, sname, shdr->sh_size)) + continue; + + dest = codetag_alloc_module_section(info->mod, sname, shdr->sh_size, + arch_mod_section_prepend(info->mod, i), shdr->sh_addralign); + if (WARN_ON(!dest)) { + codetag_free_module_sections(info->mod); + return -EINVAL; + } + if (dest == ERR_PTR(-EAGAIN)) + / Allocate the section as a regular section. / + continue; + if (IS_ERR(dest)) { + codetag_free_module_sections(info->mod); + return PTR_ERR(dest); + } + + if (shdr->sh_type != SHT_NOBITS) + memcpy(dest, (void )shdr->sh_addr, shdr->sh_size); + else + memset(dest, 0, shdr->sh_size); + shdr->sh_addr = (unsigned long)dest; + shdr->sh_entsize = SH_ENTSIZE_STANDALONE; + } + + return 0; +} + static struct module layout_and_allocate(struct load_info info, int flags) { struct module mod; + unsigned int i; int err; / Allow arches to frob section contents and sizes. / @@ -2967,8 +2968,13 @@ static struct module layout_and_allocate(struct load_info info, int flags) if (err < 0) return ERR_PTR(err); + / Repurpose sh_entsize to track where each section is allocated. / + for (i = 0; i < info->hdr->e_shnum; i++) + info->sechdrs[i].sh_entsize = ~0UL; + / We will do a special allocation for per-cpu sections later. / - info->sechdrs[info->index.pcpu].sh_flags &= ~(unsigned long)SHF_ALLOC; + if (info->index.pcpu) + info->sechdrs[info->index.pcpu].sh_entsize = SH_ENTSIZE_STANDALONE; / * Mark relevant sections as SHF_RO_AFTER_INIT so layout_sections() can @@ -2977,18 +2983,21 @@ static struct module layout_and_allocate(struct load_info info, int flags) / module_mark_ro_after_init(info->hdr, info->sechdrs, info->secstrings); - / - * Determine total sizes, and put offsets in sh_entsize. For now - * this is done generically; there doesn't appear to be any - * special cases for the architectures. - / + / Allow codetag sections to be allocated separately first. / + err = allocate_codetag_sections(info); + if (err) + return ERR_PTR(err); + + / Determine total sizes and put offsets in sh_entsize. / layout_sections(info->mod, info); layout_symtab(info->mod, info); / Allocate and move to the final place / err = move_module(info->mod, info); - if (err) + if (err) { + codetag_free_module_sections(info->mod); return ERR_PTR(err); + } / Module has been copied to its final place now: return it. / mod = (void )info->sechdrs[info->index.mod].sh_addr; diff --git a/kernel/module/sysfs.c b/kernel/module/sysfs.c index 01c65d6088737..15c6baeb39c4c 100644 --- a/kernel/module/sysfs.c +++ b/kernel/module/sysfs.c @@ -62,6 +62,15 @@ static void free_sect_attrs(struct module_sect_attrs sect_attrs) kfree(sect_attrs); } +/ + * .data..percpu has a separate allocation per CPU and no single + * address to report. + / +static bool sect_visible(const struct load_info info, unsigned int i) +{ + return !sect_empty(&info->sechdrs[i]) && i != info->index.pcpu; +} + static int add_sect_attrs(struct module mod, const struct load_info info) { struct module_sect_attrs sect_attrs; @@ -72,7 +81,7 @@ static int add_sect_attrs(struct module mod, const struct load_info info) / Count loaded sections and allocate structures / for (i = 0; i < info->hdr->e_shnum; i++) - if (!sect_empty(&info->sechdrs[i])) + if (sect_visible(info, i)) nloaded++; sect_attrs = kzalloc_flex(sect_attrs, attrs, nloaded); if (!sect_attrs) @@ -92,7 +101,7 @@ static int add_sect_attrs(struct module mod, const struct load_info info) for (i = 0; i < info->hdr->e_shnum; i++) { Elf_Shdr sec = &info->sechdrs[i]; - if (sect_empty(sec)) + if (!sect_visible(info, i)) continue; sysfs_bin_attr_init(sattr); sattr->attr.name = @@ -159,7 +168,7 @@ static int add_notes_attrs(struct module mod, const struct load_info info) / Count notes sections and allocate structures. / notes = 0; for (i = 0; i < info->hdr->e_shnum; i++) - if (!sect_empty(&info->sechdrs[i]) && + if (sect_visible(info, i) && info->sechdrs[i].sh_type == SHT_NOTE) ++notes; @@ -181,7 +190,7 @@ static int add_notes_attrs(struct module mod, const struct load_info info) nattr = &notes_attrs->attrs[0]; for (loaded = i = 0; i < info->hdr->e_shnum; ++i) { - if (sect_empty(&info->sechdrs[i])) + if (!sect_visible(info, i)) continue; if (info->sechdrs[i].sh_type == SHT_NOTE) { sysfs_bin_attr_init(nattr); diff --git a/lib/codetag.c b/lib/codetag.c index a9cda4c962a30..a0b600720afc1 100644 --- a/lib/codetag.c +++ b/lib/codetag.c @@ -240,7 +240,9 @@ static int codetag_module_init(struct codetag_type cttype, struct module mod) if (err < 0) { kfree(cmod); - return err; + / -EOPNOTSUPP means we can load the module without its tag. / + if (err != -EOPNOTSUPP) + return err; } return 0; @@ -388,7 +390,11 @@ void codetag_unload_module(struct module mod) ++cttype->content_id; } up_write(&cttype->mod_lock); - if (found && cttype->desc.free_section_mem) + /* + * A module whose module_load() returned -EOPNOTSUPP is not + * in the idr but may still hold reserved section memory. + / + if (cttype->desc.free_section_mem) cttype->desc.free_section_mem(mod, true); } mutex_unlock(&codetag_lock); diff --git a/mm/alloc_tag.c b/mm/alloc_tag.c index b334103104779..cfa0fc84b68f9 100644 --- a/mm/alloc_tag.c +++ b/mm/alloc_tag.c @@ -15,6 +15,7 @@ #include <linux/seq_file.h> #include <linux/string_choices.h> #include <linux/vmalloc.h> +#include <linux/workqueue.h> #include <linux/kmemleak.h> #include <uapi/linux/alloc_tag.h> @@ -591,6 +592,13 @@ void pgalloc_tag_swap(struct folio new, struct folio old) put_page_tag_ref(handle_new); } +static void remove_allocinfo_file(struct work_struct work) +{ + remove_proc_entry(ALLOCINFO_FILE_NAME, NULL); +} + +static DECLARE_WORK(remove_allocinfo_work, remove_allocinfo_file); + static void shutdown_mem_profiling(bool remove_file) { if (mem_alloc_profiling_enabled()) @@ -600,7 +608,7 @@ static void shutdown_mem_profiling(bool remove_file) return; if (remove_file) - remove_proc_entry(ALLOCINFO_FILE_NAME, NULL); + schedule_work(&remove_allocinfo_work); mem_profiling_support = false; } @@ -804,6 +812,13 @@ static int vm_module_tags_populate(void) next_page, PAGE_SHIFT) < 0) { release_pages_arg arg = { .pages = next_page }; + /* + * vmap_pages_range() only runs once all pages were + * allocated, and it may have installed some mappings + * before failing. Undo them. + / + if (nr == more_pages) + vunmap_range(phys_end, phys_end + (nr << PAGE_SHIFT)); / Clean up and error out / release_pages(arg, nr); return -ENOMEM; @@ -835,6 +850,52 @@ static int vm_module_tags_populate(void) return 0; } +static void release_module_tags(struct module mod, bool used) +{ + MA_STATE(mas, &mod_area_mt, module_tags.size, module_tags.size); + struct alloc_tag start_tag; + struct alloc_tag end_tag; + struct module val; + + mas_lock(&mas); + mas_for_each_rev(&mas, val, 0) + if (val == mod) + break; + + if (!val) / module not found / + goto out; + + if (!used) + goto release_area; + + start_tag = (struct alloc_tag )(module_tags.start_addr + mas.index); + end_tag = (struct alloc_tag )(module_tags.start_addr + mas.last); + if (!clean_unused_counters(start_tag, end_tag)) { + struct alloc_tag tag; + + for (tag = start_tag; tag <= end_tag; tag++) { + struct alloc_tag_counters counter; + + if (!tag->counters) + continue; + + counter = alloc_tag_read(tag); + pr_info("%s:%u module %s func:%s has %llu allocated at module unload\n", + tag->ct.filename, tag->ct.lineno, tag->ct.modname, + tag->ct.function, counter.bytes); + } + } else { + used = false; + } +release_area: + mas_store(&mas, used ? &unloaded_mod : NULL); + val = mas_prev_range(&mas, 0); + if (val == &prepend_mod) + mas_store(&mas, NULL); +out: + mas_unlock(&mas); +} + static void reserve_module_tags(struct module mod, unsigned long size, unsigned int prepend, unsigned long align) { @@ -901,13 +962,17 @@ static void reserve_module_tags(struct module mod, unsigned long size, return ret; if (module_tags.size < offset + size) { + unsigned long prev_size = module_tags.size; int grow_res; module_tags.size = offset + size; - if (mem_alloc_profiling_enabled() && !tags_addressable()) { + if (!tags_addressable()) { shutdown_mem_profiling(true); - pr_warn("With module %s there are too many tags to fit in %d page flag bits. Memory allocation profiling is disabled!\n", - mod->name, NR_UNUSED_PAGEFLAG_BITS); + pr_warn_once("With module %s there are too many tags to fit in %d page flag bits. Memory allocation profiling is disabled!\n", + mod->name, NR_UNUSED_PAGEFLAG_BITS); + release_module_tags(mod, false); + module_tags.size = prev_size; + return ERR_PTR(-EAGAIN); } grow_res = vm_module_tags_populate(); @@ -915,6 +980,8 @@ static void reserve_module_tags(struct module mod, unsigned long size, shutdown_mem_profiling(true); pr_err("Failed to allocate memory for allocation tags in the module %s. Memory allocation profiling is disabled!\n", mod->name); + release_module_tags(mod, false); + module_tags.size = prev_size; return ERR_PTR(grow_res); } } @@ -922,52 +989,6 @@ static void reserve_module_tags(struct module mod, unsigned long size, return (struct alloc_tag )(module_tags.start_addr + offset); } -static void release_module_tags(struct module mod, bool used) -{ - MA_STATE(mas, &mod_area_mt, module_tags.size, module_tags.size); - struct alloc_tag start_tag; - struct alloc_tag end_tag; - struct module val; - - mas_lock(&mas); - mas_for_each_rev(&mas, val, 0) - if (val == mod) - break; - - if (!val) / module not found / - goto out; - - if (!used) - goto release_area; - - start_tag = (struct alloc_tag )(module_tags.start_addr + mas.index); - end_tag = (struct alloc_tag )(module_tags.start_addr + mas.last); - if (!clean_unused_counters(start_tag, end_tag)) { - struct alloc_tag tag; - - for (tag = start_tag; tag <= end_tag; tag++) { - struct alloc_tag_counters counter; - - if (!tag->counters) - continue; - - counter = alloc_tag_read(tag); - pr_info("%s:%u module %s func:%s has %llu allocated at module unload\n", - tag->ct.filename, tag->ct.lineno, tag->ct.modname, - tag->ct.function, counter.bytes); - } - } else { - used = false; - } -release_area: - mas_store(&mas, used ? &unloaded_mod : NULL); - val = mas_prev_range(&mas, 0); - if (val == &prepend_mod) - mas_store(&mas, NULL); -out: - mas_unlock(&mas); -} - static int load_module(struct module mod, struct codetag start, struct codetag stop) { / Allocate module alloc_tag percpu counters / @@ -975,6 +996,10 @@ static int load_module(struct module mod, struct codetag start, struct codetag struct alloc_tag stop_tag; struct alloc_tag tag; + / Profiling disabled: load the module without its tags. / + if (!mem_profiling_support) + return -EOPNOTSUPP; + / percpu counters for core allocations are already statically allocated */ if (!mod) return 0; @@ -1341,16 +1366,10 @@ static int __init alloc_tag_init(void) return 0; } - if (!proc_create(ALLOCINFO_FILE_NAME, 0400, NULL, &allocinfo_proc_ops)) { - pr_err("Failed to create %s file\n", ALLOCINFO_FILE_NAME); - shutdown_mem_profiling(false); - return -ENOMEM; - } - res = alloc_mod_tags_mem(); if (res) { pr_err("Failed to reserve address space for module tags, errno = %d\n", res); - shutdown_mem_profiling(true); + shutdown_mem_profiling(false); return res; } @@ -1358,10 +1377,16 @@ static int __init alloc_tag_init(void) if (IS_ERR(alloc_tag_cttype)) { pr_err("Allocation tags registration failed, errno = %pe\n", alloc_tag_cttype); free_mod_tags_mem(); - shutdown_mem_profiling(true); + shutdown_mem_profiling(false); return PTR_ERR(alloc_tag_cttype); } + if (!proc_create(ALLOCINFO_FILE_NAME, 0400, NULL, &allocinfo_proc_ops)) { + pr_err("Failed to create %s file\n", ALLOCINFO_FILE_NAME); + shutdown_mem_profiling(false); + return -ENOMEM; + } + return 0; } module_init(alloc_tag_init);
65/3	2026/09/15 07:39	llm	kmsan-evaluator	1m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 9830 output: 20 thoughts: 1841 Thoughts: KMSAN Fuzzing Session Assessment Alright, let's break this down. The task is to determine if this patch series warrants a dedicated KMSAN fuzzing session, beyond the usual KASAN coverage. The goal is to catch uninitialized memory reads and kernel-to-user info-leaks, so we have to carefully assess if this code introduces the potential for those. The instructions are clear: if standard bug detectors (KASAN, LOCKDEP, etc.) cover it, KMSAN is unnecessary. It's all about finding those specific vulnerabilities, especially around data structures being sent to user space or conditional logic influenced by uninitialized data. Looking at the patch itself, it seems to focus on module handling and codetag integration, with modifications across several files. Specifically, the introduction of `MOD_STANDALONE` and the associated changes in `kernel/module/main.c` are grabbing my attention. We're getting a new section type (`SH_ENTSIZE_STANDALONE`) and a new function `allocate_codetag_sections`. My initial read suggests that there's a shift in how standalone sections are allocated and handled. It seems that `allocate_codetag_sections` is now responsible for allocating sections for "codetags" and if they are standalone. The logic within `allocate_codetag_sections` copies data to these sections, or zeroes them if they are `SHT_NOBITS`. Crucially, these standalone sections are skipped in `move_module`, and the sh_entsize is set to `SH_ENTSIZE_STANDALONE`. The `sect_visible` function now excludes these from the sysfs, and changes in the alloc_tag system seem to be linked to allocinfo. The code changes in `layout_sections` and `layout_and_allocate` might introduce uninitialized fields, but I'm thinking, are these sections actually sent to user space? I need to know. The `allocate_codetag_sections` does a memcpy / memset. This looks fine from the surface, though my concern is the branching logic and conditional logic that might depend on uninitialized variables. Therefore, my current assessment is to investigate whether this new standalone section information is ever exposed to user space. If not, this is likely a refactor rather than a feature. If it is exposed to user space, I must delve deeper to examine the initialization of these sections and any conditional logic that might depend on data from them. If so, a KMSAN session might be warranted. I'll need to explore the surrounding code and do a deeper dive using grepper/read-file to determine the precise data flow and whether we have a risk of uninitialized memory reads or information leaks.
66/3	2026/09/15 07:40	tool	grepper	0m Args: { "Expression": "allocate_codetag_sections" } Results: { "Output": "kernel/module/main.c=2909=core_param(module_blacklist, module_blacklist, charp, 0400);\n--\nkernel/module/main.c-2918- /\nkernel/module/main.c:2919:static int allocate_codetag_sections(struct load_info info)\nkernel/module/main.c-2920-{\n--\nkernel/module/main.c=2954=static struct module layout_and_allocate(struct load_info info, int flags)\n--\nkernel/module/main.c-2986-\t/* Allow codetag sections to be allocated separately first. */\nkernel/module/main.c:2987:\terr = allocate_codetag_sections(info);\nkernel/module/main.c-2988-\tif (err)\n" }
67/3	2026/09/15 07:40	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 12485 output: 22 thoughts: 68 Thoughts: Okay, let's dive into these commits. My initial thought is, "What drove these changes? What was the rationale behind this?" My first step would be to delve into the commit history. I'll need to leverage `git log` or meticulously review the individual commit messages and details to understand the context and purpose. From there, I'll need to understand how various pieces interact. I'll use grep or a similar tool to see how things like `SH_ENTSIZE_STANDALONE`, `allocate_codetag_sections`, or `codetag_alloc_module_section` come together. It's time to follow the thread of these specific identifiers and understand the flow of the related code.
68/3	2026/09/15 07:40	tool	grepper	0m Args: { "Expression": "SH_ENTSIZE_STANDALONE" } Results: { "Output": "kernel/module/internal.h-35- /\nkernel/module/internal.h:36:#define SH_ENTSIZE_STANDALONE\t\t\t\t\t\\\nkernel/module/internal.h-37-\t(((unsigned long)MOD_STANDALONE \u0026 SH_ENTSIZE_TYPE_MASK)\t\\\n--\nkernel/module/main.c=2780=static int move_module(struct module mod, struct load_info info)\n--\nkernel/module/main.c-2804-\t\tif (!(shdr-\u003esh_flags \u0026 SHF_ALLOC)\nkernel/module/main.c:2805:\t\t \|\| shdr-\u003esh_entsize == SH_ENTSIZE_STANDALONE)\nkernel/module/main.c-2806-\t\t\tcontinue;\n--\nkernel/module/main.c=2919=static int allocate_codetag_sections(struct load_info info)\n--\nkernel/module/main.c-2947-\t\tshdr-\u003esh_addr = (unsigned long)dest;\nkernel/module/main.c:2948:\t\tshdr-\u003esh_entsize = SH_ENTSIZE_STANDALONE;\nkernel/module/main.c-2949-\t}\n--\nkernel/module/main.c=2954=static struct module layout_and_allocate(struct load_info info, int flags)\n--\nkernel/module/main.c-2976-\tif (info-\u003eindex.pcpu)\nkernel/module/main.c:2977:\t\tinfo-\u003esechdrs[info-\u003eindex.pcpu].sh_entsize = SH_ENTSIZE_STANDALONE;\nkernel/module/main.c-2978-\n" }
69/3	2026/09/15 07:40	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 13150 output: 37 thoughts: 47 Thoughts: Investigating the Core Symbol Identification Alright, let's dive right in. My initial thought is to zero in on the `is_core_symbol` function, specifically within the `kernel/module/kallsyms.c` file. Given the task at hand, that seems like the logical starting point for understanding how core symbols are identified within the kernel module space. I need to refresh my memory, so I'll start by reading around line 76 in that file. That should give me a good context for how this function operates. I need to get a clear picture of its implementation and its role in the broader symbol resolution process. Let's see what that code reveals.
70/3	2026/09/15 07:41	tool	read-file	0m Args: { "File": "kernel/module/kallsyms.c", "FirstLine": 70, "LineCount": 50 } Results: { "Contents": " 70:\t\t}\n 71:\t\tif (strstarts(info-\u003esecstrings + sechdrs[sym-\u003est_shndx].sh_name,\n 72:\t\t\t \".debug\")) {\n 73:\t\t\treturn 'n';\n 74:\t\t}\n 75:\t\treturn '?';\n 76:\t}\n 77:\t\n 78:\tstatic bool is_core_symbol(const Elf_Sym src, const Elf_Shdr sechdrs,\n 79:\t\t\t\t unsigned int shnum)\n 80:\t{\n 81:\t\tconst Elf_Shdr sec;\n 82:\t\tenum mod_mem_type type;\n 83:\t\n 84:\t\tif (src-\u003est_shndx == SHN_UNDEF \|\|\n 85:\t\t src-\u003est_shndx \u003e= shnum \|\|\n 86:\t\t !src-\u003est_name)\n 87:\t\t\treturn false;\n 88:\t\n 89:\t\tsec = sechdrs + src-\u003est_shndx;\n 90:\t\ttype = sec-\u003esh_entsize \u003e\u003e SH_ENTSIZE_TYPE_SHIFT;\n 91:\t\tif (!(sec-\u003esh_flags \u0026 SHF_ALLOC)\n 92:\t#ifndef CONFIG_KALLSYMS_ALL\n 93:\t\t \|\| !(sec-\u003esh_flags \u0026 SHF_EXECINSTR)\n 94:\t#endif\n 95:\t\t \|\| mod_mem_type_is_init(type))\n 96:\t\t\treturn false;\n 97:\t\n 98:\t\treturn true;\n 99:\t}\n 100:\t\n 101:\t/\n 102:\t * We only allocate and copy the strings needed by the parts of symtab\n 103:\t * we keep. This is simple, but has the effect of making multiple\n 104:\t * copies of duplicates. We could be more sophisticated, see\n 105:\t * linux-kernel thread starting with\n 106:\t * \u003c73defb5e4bca04a6431392cc341112b1@localhost\u003e.\n 107:\t /\n 108:\tvoid layout_symtab(struct module mod, struct load_info info)\n 109:\t{\n 110:\t\tElf_Shdr symsect = info-\u003esechdrs + info-\u003eindex.sym;\n 111:\t\tElf_Shdr strsect = info-\u003esechdrs + info-\u003eindex.str;\n 112:\t\tconst Elf_Sym src;\n 113:\t\tunsigned int i, nsrc, ndst, strtab_size = 0;\n 114:\t\tstruct module_memory mod_mem_data = \u0026mod-\u003emem[MOD_DATA];\n 115:\t\tstruct module_memory mod_mem_init_data = \u0026mod-\u003emem[MOD_INIT_DATA];\n 116:\t\n 117:\t\t/* Put symbol section at end of init part of module. */\n 118:\t\tsymsect-\u003esh_flags \|= SHF_ALLOC;\n 119:\t\tsymsect-\u003esh_entsize = module_get_offset_and_type(mod, MOD_INIT_DATA,\n" }
71/3	2026/09/15 07:41	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 14198 output: 23 thoughts: 341 Thoughts: Analyzing the Core Symbol Determination Okay, let's break this down. In the `is_core_symbol` function, the code checks if a symbol should be considered "core." It grabs the section header (`sec`) and its type. Then, it uses a few conditions: is the section allocatable (`SHF_ALLOC`), executable (`SHF_EXECINSTR`), and is it an "init" section type? The crucial bit is the removal of the `SHF_ALLOC` flag for per-CPU sections in the `layout_and_allocate` function before the patch. That meant that per-CPU symbols wouldn't be considered core symbols unless a special check was included, specifically: ```c #ifdef CONFIG_KALLSYMS_ALL if (src->st_shndx == pcpundx) return true; #endif ``` Now, with this patch, `SHF_ALLOC` is not being cleared for per-CPU sections. This is important, and makes me think we need to carefully consider the implications. Now, the `sh_entsize` is set to `SH_ENTSIZE_STANDALONE`. This has consequences. What is the value of `type` in this scenario? I remember, `MOD_STANDALONE = -2`. This is the key. Let's make sure our assumptions are correct, what is the behavior of `mod_mem_type_is_init(MOD_STANDALONE)`? That's the question.
72/3	2026/09/15 07:41	tool	grepper	0m Args: { "Expression": "mod_mem_type_is_init" } Results: { "Output": "include/linux/module.h=318=enum mod_mem_type {\n--\ninclude/linux/module.h-332-\ninclude/linux/module.h:333:#define mod_mem_type_is_init(type)\t\\\ninclude/linux/module.h-334-\t((type) == MOD_INIT_TEXT \|\|\t\\\n--\ninclude/linux/module.h-337-\ninclude/linux/module.h:338:#define mod_mem_type_is_core(type) (!mod_mem_type_is_init(type))\ninclude/linux/module.h-339-\n--\nkernel/module/kallsyms.c=78=static bool is_core_symbol(const Elf_Sym src, const Elf_Shdr sechdrs,\n--\nkernel/module/kallsyms.c-94-#endif\nkernel/module/kallsyms.c:95:\t \|\| mod_mem_type_is_init(type))\nkernel/module/kallsyms.c-96-\t\treturn false;\n" }
73/3	2026/09/15 07:41	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 15169 output: 27 thoughts: 648 Thoughts: Analyzing Module Section Allocation Okay, let's break this down. First, I see `mod_mem_type_is_init(type)` checking for initialization types, and it's clear `MOD_STANDALONE` isn't among them. Got it. Per-CPU symbols are now considered core symbols if `CONFIG_KALLSYMS_ALL` is set (or if the section is execinstr, but percpu isn't, so that's not relevant here). That's a key distinction. Now, looking at `allocate_codetag_sections`, I'm dissecting how module sections are handled. Specifically, I see this loop iterating through section headers within a `load_info` struct. It's skipping sections that don't meet a certain codetag criteria. If a section is selected to be copied: `if (shdr->sh_type != SHT_NOBITS)` ` memcpy(dest, (void )shdr->sh_addr, shdr->sh_size);` `else` ` memset(dest, 0, shdr->sh_size);` This is where it gets interesting. I notice that the code is copying* data from `(void *)shdr->sh_addr` into a newly allocated `dest` buffer if it's not a NOBITS section; otherwise, it's zeroing out the buffer. The critical question here is whether `shdr->sh_addr` is valid at the point `allocate_codetag_sections` is called. Is it pointing to the right place in the loaded module file? Now, I'm going to track down how `shdr->sh_addr` is set when a module is loaded. I need to understand what's stored in `shdr->sh_addr` at the time this function is called. That'll tell me if this copy or zero-init will actually work correctly.
74/3	2026/09/15 07:42	tool	grepper	0m Args: { "Expression": "sh_addr", "PathPrefix": "kernel/module/" } Results: { "Output": "kernel/module/kallsyms.c=108=void layout_symtab(struct module mod, struct load_info info)\n--\nkernel/module/kallsyms.c-135-\t/* Append room for core symbols at end of core part. /\nkernel/module/kallsyms.c:136:\tinfo-\u003esymoffs = ALIGN(mod_mem_data-\u003esize, symsect-\u003esh_addralign ?: 1);\nkernel/module/kallsyms.c-137-\tinfo-\u003estroffs = mod_mem_data-\u003esize = info-\u003esymoffs + ndst sizeof(Elf_Sym);\n--\nkernel/module/kallsyms.c=164=void add_kallsyms(struct module mod, const struct load_info info)\n--\nkernel/module/kallsyms.c-177-\nkernel/module/kallsyms.c:178:\tkallsyms-\u003esymtab = (void )symsec-\u003esh_addr;\nkernel/module/kallsyms.c-179-\tkallsyms-\u003enum_symtab = symsec-\u003esh_size / sizeof(Elf_Sym);\nkernel/module/kallsyms.c-180-\t/ Make sure we get permanent strtab: don't use info-\u003estrtab. /\nkernel/module/kallsyms.c:181:\tkallsyms-\u003estrtab = (void )info-\u003esechdrs[info-\u003eindex.str].sh_addr;\nkernel/module/kallsyms.c-182-\tkallsyms-\u003etypetab = init_data_base + info-\u003einit_typeoffs;\n--\nkernel/module/kallsyms.c=218=void init_build_id(struct module mod, const struct load_info info)\n--\nkernel/module/kallsyms.c-225-\t\tif (!sect_empty(sechdr) \u0026\u0026 sechdr-\u003esh_type == SHT_NOTE \u0026\u0026\nkernel/module/kallsyms.c:226:\t\t !build_id_parse_buf((void )sechdr-\u003esh_addr, mod-\u003ebuild_id,\nkernel/module/kallsyms.c-227-\t\t\t\t\tsechdr-\u003esh_size))\n--\nkernel/module/livepatch.c=18=int copy_module_elf(struct module mod, struct load_info info)\n--\nkernel/module/livepatch.c-53-\t For livepatch modules, core_kallsyms.symtab is a complete\nkernel/module/livepatch.c:54:\t * copy of the original symbol table. Adjust sh_addr to point\nkernel/module/livepatch.c-55-\t * to core_kallsyms.symtab since the copy of the symtab in module\n--\nkernel/module/livepatch.c-57-\t /\nkernel/module/livepatch.c:58:\tmod-\u003eklp_info-\u003esechdrs[symndx].sh_addr = (unsigned long)mod-\u003ecore_kallsyms.symtab;\nkernel/module/livepatch.c-59-\n--\nkernel/module/main.c=284=static void section_addr(const struct load_info info, const char name)\nkernel/module/main.c-285-{\nkernel/module/main.c:286:\t/* Section 0 has sh_addr 0. /\nkernel/module/main.c:287:\treturn (void )info-\u003esechdrs[find_sec(info, name)].sh_addr;\nkernel/module/main.c-288-}\n--\nkernel/module/main.c=291=static void section_objs(const struct load_info info,\n--\nkernel/module/main.c-297-\nkernel/module/main.c:298:\t/* Section 0 has sh_addr 0 and sh_size 0. /\nkernel/module/main.c-299-\tnum = info-\u003esechdrs[sec].sh_size / object_size;\nkernel/module/main.c:300:\treturn (void )info-\u003esechdrs[sec].sh_addr;\nkernel/module/main.c-301-}\n--\nkernel/module/main.c=320=static __maybe_unused void any_section_objs(const struct load_info info,\n--\nkernel/module/main.c-326-\nkernel/module/main.c:327:\t/ Section 0 has sh_addr 0 and sh_size 0. /\nkernel/module/main.c-328-\tnum = info-\u003esechdrs[sec].sh_size / object_size;\nkernel/module/main.c:329:\treturn (void )info-\u003esechdrs[sec].sh_addr;\nkernel/module/main.c-330-}\n--\nkernel/module/main.c=455=static int percpu_modalloc(struct module mod, struct load_info info)\n--\nkernel/module/main.c-457-\tElf_Shdr pcpusec = \u0026info-\u003esechdrs[info-\u003eindex.pcpu];\nkernel/module/main.c:458:\tunsigned long align = pcpusec-\u003esh_addralign;\nkernel/module/main.c-459-\n--\nkernel/module/main.c=1138=static char get_next_modinfo(const struct load_info info, const char tag,\n--\nkernel/module/main.c-1147-\t get_modinfo() calls made before rewrite_section_headers()\nkernel/module/main.c:1148:\t * must use sh_offset, as sh_addr isn't set!\nkernel/module/main.c-1149-\t /\n--\nkernel/module/main.c=1529=static int simplify_symbols(struct module mod, const struct load_info info)\n--\nkernel/module/main.c-1531-\tElf_Shdr symsec = \u0026info-\u003esechdrs[info-\u003eindex.sym];\nkernel/module/main.c:1532:\tElf_Sym sym = (void )symsec-\u003esh_addr;\nkernel/module/main.c-1533-\tunsigned long secbase;\n--\nkernel/module/main.c-1597-\t\t\telse\nkernel/module/main.c:1598:\t\t\t\tsecbase = info-\u003esechdrs[sym[i].st_shndx].sh_addr;\nkernel/module/main.c-1599-\t\t\tsym[i].st_value += secbase;\n--\nkernel/module/main.c=1657=long module_get_offset_and_type(struct module mod, enum mod_mem_type type,\n--\nkernel/module/main.c-1663-\tmod-\u003emem[type].size += arch_mod_section_prepend(mod, section);\nkernel/module/main.c:1664:\toffset = ALIGN(mod-\u003emem[type].size, sechdr-\u003esh_addralign ?: 1);\nkernel/module/main.c-1665-\tmod-\u003emem[type].size = offset + sechdr-\u003esh_size;\n--\nkernel/module/main.c=1922=static int elf_validity_cache_sechdrs(struct load_info info)\n--\nkernel/module/main.c-1957-\t \|\| sechdrs[0].sh_size != 0\nkernel/module/main.c:1958:\t \|\| sechdrs[0].sh_addr != 0) {\nkernel/module/main.c-1959-\t\tpr_err(\"ELF Spec violation: section 0 type(%d)!=SH_NULL or non-zero len or addr\\n\",\n--\nkernel/module/main.c=2523=static int rewrite_section_headers(struct load_info info, int flags)\n--\nkernel/module/main.c-2527-\t/ This should always be true, but let's be sure. /\nkernel/module/main.c:2528:\tinfo-\u003esechdrs[0].sh_addr = 0;\nkernel/module/main.c-2529-\n--\nkernel/module/main.c-2533-\t\t/\nkernel/module/main.c:2534:\t\t * Mark all sections sh_addr with their address in the\nkernel/module/main.c-2535-\t\t * temporary image.\nkernel/module/main.c-2536-\t\t /\nkernel/module/main.c:2537:\t\tshdr-\u003esh_addr = (size_t)info-\u003ehdr + shdr-\u003esh_offset;\nkernel/module/main.c-2538-\n--\nkernel/module/main.c=2780=static int move_module(struct module mod, struct load_info info)\n--\nkernel/module/main.c-2822-\t\t\t}\nkernel/module/main.c:2823:\t\t\tmemcpy(dest, (void )shdr-\u003esh_addr, shdr-\u003esh_size);\nkernel/module/main.c-2824-\t\t}\n--\nkernel/module/main.c-2830-\t\t /\nkernel/module/main.c:2831:\t\tshdr-\u003esh_addr = (unsigned long)dest;\nkernel/module/main.c:2832:\t\tpr_debug(\"\\t0x%lx 0x%.8lx %s\\n\", (long)shdr-\u003esh_addr,\nkernel/module/main.c-2833-\t\t\t (long)shdr-\u003esh_size, info-\u003esecstrings + shdr-\u003esh_name);\n--\nkernel/module/main.c=2919=static int allocate_codetag_sections(struct load_info info)\n--\nkernel/module/main.c-2929-\t\tdest = codetag_alloc_module_section(info-\u003emod, sname, shdr-\u003esh_size,\nkernel/module/main.c:2930:\t\t\t\tarch_mod_section_prepend(info-\u003emod, i), shdr-\u003esh_addralign);\nkernel/module/main.c-2931-\t\tif (WARN_ON(!dest)) {\n--\nkernel/module/main.c-2943-\t\tif (shdr-\u003esh_type != SHT_NOBITS)\nkernel/module/main.c:2944:\t\t\tmemcpy(dest, (void )shdr-\u003esh_addr, shdr-\u003esh_size);\nkernel/module/main.c-2945-\t\telse\nkernel/module/main.c-2946-\t\t\tmemset(dest, 0, shdr-\u003esh_size);\nkernel/module/main.c:2947:\t\tshdr-\u003esh_addr = (unsigned long)dest;\nkernel/module/main.c-2948-\t\tshdr-\u003esh_entsize = SH_ENTSIZE_STANDALONE;\n--\nkernel/module/main.c=2954=static struct module layout_and_allocate(struct load_info info, int flags)\n--\nkernel/module/main.c-3002-\t/ Module has been copied to its final place now: return it. /\nkernel/module/main.c:3003:\tmod = (void )info-\u003esechdrs[info-\u003eindex.mod].sh_addr;\nkernel/module/main.c-3004-\tkmemleak_load_module(mod, info);\n--\nkernel/module/main.c=3027=static int post_relocation(struct module mod, const struct load_info info)\n--\nkernel/module/main.c-3032-\t/* Copy relocated percpu area over. /\nkernel/module/main.c:3033:\tpercpu_modcopy(mod, (void )info-\u003esechdrs[info-\u003eindex.pcpu].sh_addr,\nkernel/module/main.c-3034-\t\t info-\u003esechdrs[info-\u003eindex.pcpu].sh_size);\n--\nkernel/module/sysfs.c=74=static int add_sect_attrs(struct module mod, const struct load_info info)\n--\nkernel/module/sysfs.c-113-\t\tsattr-\u003eread = module_sect_read;\nkernel/module/sysfs.c:114:\t\tsattr-\u003eprivate = (void )sec-\u003esh_addr;\nkernel/module/sysfs.c-115-\t\tsattr-\u003esize = MODULE_SECT_READ_SIZE;\n--\nkernel/module/sysfs.c=160=static int add_notes_attrs(struct module mod, const struct load_info info)\n--\nkernel/module/sysfs.c-199-\t\t\tnattr-\u003esize = info-\u003esechdrs[i].sh_size;\nkernel/module/sysfs.c:200:\t\t\tnattr-\u003eprivate = (void )info-\u003esechdrs[i].sh_addr;\nkernel/module/sysfs.c-201-\t\t\tnattr-\u003eread = sysfs_bin_attr_simple_read;\n--\nkernel/module/version.c=13=int check_version(const struct load_info info,\n--\nkernel/module/version.c-47-\nkernel/module/version.c:48:\tversions = (void )sechdrs[versindex].sh_addr;\nkernel/module/version.c-49-\tnum_versions = sechdrs[versindex].sh_size\n--\nkernel/module/version.c=107=void modversion_ext_start(const struct load_info info,\n--\nkernel/module/version.c-122-\nkernel/module/version.c:123:\tstart-\u003ecrc = (const u32 )sechdrs[crc_idx].sh_addr;\nkernel/module/version.c:124:\tstart-\u003ename = (const char )sechdrs[name_idx].sh_addr;\nkernel/module/version.c-125-\tstart-\u003eremaining = sechdrs[crc_idx].sh_size / sizeof(start-\u003ecrc);\n" }
75/3	2026/09/15 07:42	llm	kmsan-evaluator	2m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 19783 output: 36 thoughts: 95 Thoughts: Here's my thought process, as I analyze this: Analyzing `rewrite_section_headers` and Memory Addressing Okay, so I'm digging into how section headers are handled, and the key function here is `rewrite_section_headers`. It looks like it sets the address of a section header (`shdr->sh_addr`) based on the image's header info and offset: `shdr->sh_addr = (size_t)info->hdr + shdr->sh_offset;`. That makes perfect sense; calculating where the section actually lives in memory given its location within the original file. Now, the big question is when this function gets called – context is everything! Since `rewrite_section_headers` is clearly within the `load_info` process, I need to know when that happens. To trace that execution path, I need to examine where the `rewrite_section_headers` is actually invoked. I should probably focus on `kernel/module/main.c` because that sounds like a likely spot. So, I'll go check that location.
76/3	2026/09/15 07:44	tool	read-file	0m Args: { "File": "kernel/module/main.c", "FirstLine": 2520, "LineCount": 40 } Results: { "Contents": "2520:\t\t\tvfree(info-\u003ehdr);\n2521:\t}\n2522:\t\n2523:\tstatic int rewrite_section_headers(struct load_info info, int flags)\n2524:\t{\n2525:\t\tunsigned int i;\n2526:\t\n2527:\t\t/ This should always be true, but let's be sure. /\n2528:\t\tinfo-\u003esechdrs[0].sh_addr = 0;\n2529:\t\n2530:\t\tfor (i = 1; i \u003c info-\u003ehdr-\u003ee_shnum; i++) {\n2531:\t\t\tElf_Shdr shdr = \u0026info-\u003esechdrs[i];\n2532:\t\n2533:\t\t\t/\n2534:\t\t\t Mark all sections sh_addr with their address in the\n2535:\t\t\t * temporary image.\n2536:\t\t\t /\n2537:\t\t\tshdr-\u003esh_addr = (size_t)info-\u003ehdr + shdr-\u003esh_offset;\n2538:\t\n2539:\t\t}\n2540:\t\n2541:\t\t/ Track but don't keep modinfo and version sections. /\n2542:\t\tinfo-\u003esechdrs[info-\u003eindex.vers].sh_flags \u0026= ~(unsigned long)SHF_ALLOC;\n2543:\t\tinfo-\u003esechdrs[info-\u003eindex.vers_ext_crc].sh_flags \u0026=\n2544:\t\t\t~(unsigned long)SHF_ALLOC;\n2545:\t\tinfo-\u003esechdrs[info-\u003eindex.vers_ext_name].sh_flags \u0026=\n2546:\t\t\t~(unsigned long)SHF_ALLOC;\n2547:\t\tinfo-\u003esechdrs[info-\u003eindex.info].sh_flags \u0026= ~(unsigned long)SHF_ALLOC;\n2548:\t\n2549:\t\treturn 0;\n2550:\t}\n2551:\t\n2552:\tstatic const char const module_license_offenders[] = {\n2553:\t\t/* driverloader was caught wrongly pretending to be under GPL /\n2554:\t\t\"driverloader\",\n2555:\t\n2556:\t\t/ lve claims to be GPL but upstream won't provide source */\n2557:\t\t\"lve\",\n2558:\t};\n2559:\t\n" }
77/3	2026/09/15 07:44	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 20767 output: 27 thoughts: 1065 Thoughts: Analyzing Module Section Allocation and Visibility Okay, let's break down this module section allocation process. The initial setup in `rewrite_section_headers` is straightforward: `shdr->sh_addr` is pointing into the temporary image within `info->hdr`. Now, `layout_and_allocate` is where the core logic resides. First, within `layout_and_allocate`, the code repurposes `sh_entsize` as a scratchpad to track allocations. It's initialized to `~0UL` for most sections. However, the per-CPU section (`info->index.pcpu`) gets a special value, `SH_ENTSIZE_STANDALONE`. This signals it has a different allocation strategy, as we know. The `module_mark_ro_after_init` call marks sections as read-only after initialization. This is followed by `allocate_codetag_sections`. Inside `allocate_codetag_sections`, it appears we're doing the explicit allocation and initialization of these code tag sections. We call `codetag_alloc_module_section` to get the destination memory (`dest`). The section content is then copied using `memcpy` or zeroed using `memset` from the original `shdr->sh_addr`, which should now contain the address in the temporary image. Crucially, `shdr->sh_addr` is then updated to point to the newly allocated `dest`, and `shdr->sh_entsize` gets `SH_ENTSIZE_STANDALONE` again. That means the code has allocated the section and, critically, updated the `sh_addr` to point at the new allocated section memory. Next, we hit `layout_sections`. Here, `__layout_sections` iterates through the sections, but it skips sections where `sh_entsize != ~0UL` This means the percpu and codetag sections are skipped, because of their `SH_ENTSIZE_STANDALONE` flag. Thus, the size of the standalone sections are not added to `mod->mem[type].size`. The crucial bit happens in `move_module`. It checks `!(shdr->sh_flags & SHF_ALLOC)` or `shdr->sh_entsize == SH_ENTSIZE_STANDALONE`. Since standalone sections have already been allocated by `allocate_codetag_sections` and we know the percpu section isn't allocated in this section, they're skipped in `move_module`! Standalone sections are already allocated and initialized. The percpu sections will be allocated later. Now, the question becomes: how are these standalone sections accounted for when reporting module information, particularly regarding sysfs attributes? I'm curious about the visibility of the allocated sections. We check `kernel/module/sysfs.c`, and we find a key line: ```c static bool sect_visible(const struct load_info *info, unsigned int i) { return !sect_empty(&info->sechdrs[i]) && i != info->index.pcpu; } ``` The percpu section is excluded for visibility, this makes sense, since it has a separate allocation per CPU and no single address to report. Previously, `info->sechdrs[info->index.pcpu].sh_flags &= ~(unsigned long)SHF_ALLOC;` had been called, but I need to check `sect_empty` function call to be certain about the behavior. This will clarify how the system treats these standalone sections in terms of their "emptiness."
78/3	2026/09/15 07:45	tool	grepper	0m Args: { "Expression": "sect_empty", "PathPrefix": "kernel/module/" } Results: { "Output": "kernel/module/internal.h=366=void add_kallsyms(struct module mod, const struct load_info info);\nkernel/module/internal.h-367-\nkernel/module/internal.h:368:static inline bool sect_empty(const Elf_Shdr sect)\nkernel/module/internal.h-369-{\n--\nkernel/module/kallsyms.c=218=void init_build_id(struct module mod, const struct load_info info)\n--\nkernel/module/kallsyms.c-224-\t\tsechdr = \u0026info-\u003esechdrs[i];\nkernel/module/kallsyms.c:225:\t\tif (!sect_empty(sechdr) \u0026\u0026 sechdr-\u003esh_type == SHT_NOTE \u0026\u0026\nkernel/module/kallsyms.c-226-\t\t !build_id_parse_buf((void )sechdr-\u003esh_addr, mod-\u003ebuild_id,\n--\nkernel/module/sysfs.c=69=static bool sect_visible(const struct load_info *info, unsigned int i)\nkernel/module/sysfs.c-70-{\nkernel/module/sysfs.c:71:\treturn !sect_empty(\u0026info-\u003esechdrs[i]) \u0026\u0026 i != info-\u003eindex.pcpu;\nkernel/module/sysfs.c-72-}\n" }
79/3	2026/09/15 07:45	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 22977 output: 35 thoughts: 11 Thoughts: Okay, here's my interpretation of that thought process, tailored for an expert audience, and written in the first person: Initial Assessment: Deconstructing `sect_empty` Right, let's dive straight in. The prompt is calling for an examination of `sect_empty`, and given the context I'm assuming this refers to a specific piece of code, perhaps a macro, function, or data structure, within a system I'm familiar with. The immediate instinct is to pinpoint the exact definition and understand its core function or purpose. I'll need to know what `sect_empty` is, formally, before I can analyze its behavior or implications. This is the foundation; without the definition, any deeper analysis is premature. Let's get that definition.
80/3	2026/09/15 07:45	tool	read-file	0m Args: { "File": "kernel/module/internal.h", "FirstLine": 365, "LineCount": 15 } Results: { "Contents": " 365:\tvoid layout_symtab(struct module mod, struct load_info info);\n 366:\tvoid add_kallsyms(struct module mod, const struct load_info info);\n 367:\t\n 368:\tstatic inline bool sect_empty(const Elf_Shdr sect)\n 369:\t{\n 370:\t\treturn !(sect-\u003esh_flags \u0026 SHF_ALLOC) \|\| sect-\u003esh_size == 0;\n 371:\t}\n 372:\t#else / !CONFIG_KALLSYMS /\n 373:\tstatic inline void init_build_id(struct module mod, const struct load_info info) { }\n 374:\tstatic inline void layout_symtab(struct module mod, struct load_info info) { }\n 375:\tstatic inline void add_kallsyms(struct module mod, const struct load_info info) { }\n 376:\t#endif / CONFIG_KALLSYMS /\n 377:\t\n 378:\t#ifdef CONFIG_SYSFS\n 379:\tint mod_sysfs_setup(struct module mod, const struct load_info *info,\n" }
81/3	2026/09/15 07:45	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 23501 output: 34 thoughts: 182 Thoughts: Analyzing Section Visibility and Code Tagging Okay, so I've been digging into this code and trying to understand the implications of these changes. It looks like `sect_empty` returned true when a section either wasn't allocated (`!(sect->sh_flags & SHF_ALLOC)`) or had a zero size (`sect->sh_size == 0`). Previously, for percpu sections, `SHF_ALLOC` was stripped away during the layout and allocation phase, which meant `sect_empty` would evaluate to true. But now, percpu sections are retaining `SHF_ALLOC`. This change led to `sect_visible` being adjusted to account for it. The logic now checks `!sect_empty(&info->sechdrs[i]) && i != info->index.pcpu`. The goal here is to ensure the sysfs behavior remains consistent, so percpu sections aren't exposed as regular sysfs attributes, even with `SHF_ALLOC` set. This is smart, keeping the external view the same. Now, I'm shifting my focus to `mm/alloc_tag.c` and `lib/codetag.c`. I want to see how these changes interact with the memory allocation tagging mechanisms. Specifically, I'm heading over to `lib/codetag.c` and will be examining lines around 240 and 388. These sections likely contain the core codetagging and the places I want to check for any interaction. Let's see what's going on there.
82/3	2026/09/15 07:46	tool	read-file	0m Args: { "File": "lib/codetag.c", "FirstLine": 230, "LineCount": 40 } Results: { "Contents": " 230:\t\t\t\telse\n 231:\t\t\t\t\tidr_remove(\u0026cttype-\u003emod_idr, mod_id);\n 232:\t\t\t} else {\n 233:\t\t\t\tcttype-\u003ecount += range_size(cttype, \u0026range);\n 234:\t\t\t\terr = 0;\n 235:\t\t\t}\n 236:\t\t} else {\n 237:\t\t\terr = mod_id;\n 238:\t\t}\n 239:\t\tup_write(\u0026cttype-\u003emod_lock);\n 240:\t\n 241:\t\tif (err \u003c 0) {\n 242:\t\t\tkfree(cmod);\n 243:\t\t\t/* -EOPNOTSUPP means we can load the module without its tag. /\n 244:\t\t\tif (err != -EOPNOTSUPP)\n 245:\t\t\t\treturn err;\n 246:\t\t}\n 247:\t\n 248:\t\treturn 0;\n 249:\t}\n 250:\t\n 251:\t#ifdef CONFIG_MODULES\n 252:\t#define CODETAG_SECTION_PREFIX\t\".codetag.\"\n 253:\t\n 254:\t/ Some codetag types need a separate module section /\n 255:\tbool codetag_needs_module_section(struct module mod, const char name,\n 256:\t\t\t\t\t unsigned long size)\n 257:\t{\n 258:\t\tconst char type_name;\n 259:\t\tstruct codetag_type *cttype;\n 260:\t\tbool ret = false;\n 261:\t\n 262:\t\tif (strncmp(name, CODETAG_SECTION_PREFIX, strlen(CODETAG_SECTION_PREFIX)))\n 263:\t\t\treturn false;\n 264:\t\n 265:\t\ttype_name = name + strlen(CODETAG_SECTION_PREFIX);\n 266:\t\tmutex_lock(\u0026codetag_lock);\n 267:\t\tlist_for_each_entry(cttype, \u0026codetag_types, link) {\n 268:\t\t\tif (strcmp(type_name, cttype-\u003edesc.section) == 0) {\n 269:\t\t\t\tif (!cttype-\u003edesc.needs_section_mem)\n" }
83/3	2026/09/15 07:46	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 24639 output: 34 thoughts: 19 Thoughts: Okay, here's my interpretation of that request, formatted as requested: Analyzing `lib/codetag.c` - Lines 380-410 Alright, let's dive into this specific section of `lib/codetag.c`. I'm focusing in on lines 380-410 because... well, let's face it, usually when I'm asked to look at a specific range, something interesting or potentially problematic is happening there. I'm going to quickly skim the surrounding context to get my bearings, then I'll parse the actual code within the requested lines. I'm looking for a few key things: potential bottlenecks, any obvious logic errors, memory leaks, and any deviations from established coding style or best practices. Given my experience, I can usually spot some common culprits right away. I'm particularly interested if there are calls to functions with side effects. I will be on the lookout for poorly documented, or entirely undocumented, code sections. Given this field, I'm already anticipating that I will need to look up a couple of the functions to clarify their use, and the associated data structures. Hopefully, it's clear and concise. If not, I'm going to form some opinions and prepare some alternative implementations. Let's see what we've got!
84/3	2026/09/15 07:46	tool	read-file	0m Args: { "File": "lib/codetag.c", "FirstLine": 375, "LineCount": 40 } Results: { "Contents": " 375:\t\t\tdown_write(\u0026cttype-\u003emod_lock);\n 376:\t\t\tidr_for_each_entry_ul(\u0026cttype-\u003emod_idr, cmod, tmp, mod_id) {\n 377:\t\t\t\tif (cmod-\u003emod \u0026\u0026 cmod-\u003emod == mod) {\n 378:\t\t\t\t\tfound = cmod;\n 379:\t\t\t\t\tbreak;\n 380:\t\t\t\t}\n 381:\t\t\t}\n 382:\t\t\tif (found) {\n 383:\t\t\t\tif (cttype-\u003edesc.module_unload)\n 384:\t\t\t\t\tcttype-\u003edesc.module_unload(cmod-\u003emod,\n 385:\t\t\t\t\t\tcmod-\u003erange.start, cmod-\u003erange.stop);\n 386:\t\n 387:\t\t\t\tcttype-\u003ecount -= range_size(cttype, \u0026cmod-\u003erange);\n 388:\t\t\t\tidr_remove(\u0026cttype-\u003emod_idr, mod_id);\n 389:\t\t\t\tkfree(cmod);\n 390:\t\t\t\t++cttype-\u003econtent_id;\n 391:\t\t\t}\n 392:\t\t\tup_write(\u0026cttype-\u003emod_lock);\n 393:\t\t\t/\n 394:\t\t\t A module whose module_load() returned -EOPNOTSUPP is not\n 395:\t\t\t * in the idr but may still hold reserved section memory.\n 396:\t\t\t /\n 397:\t\t\tif (cttype-\u003edesc.free_section_mem)\n 398:\t\t\t\tcttype-\u003edesc.free_section_mem(mod, true);\n 399:\t\t}\n 400:\t\tmutex_unlock(\u0026codetag_lock);\n 401:\t}\n 402:\t#endif / CONFIG_MODULES /\n 403:\t\n 404:\tstruct codetag_type \n 405:\tcodetag_register_type(const struct codetag_type_desc desc)\n 406:\t{\n 407:\t\tstruct codetag_type cttype;\n 408:\t\tint err;\n 409:\t\n 410:\t\tBUG_ON(desc-\u003etag_size \u003c= 0);\n 411:\t\n 412:\t\tcttype = kzalloc_obj(*cttype);\n 413:\t\tif (unlikely(!cttype))\n 414:\t\t\treturn ERR_PTR(-ENOMEM);\n" }
85/3	2026/09/15 07:46	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 25590 output: 35 thoughts: 55 Thoughts: Okay, let's dive into this. I'm going to focus on `mm/alloc_tag.c` and specifically look at those sections you've highlighted. Analyzing Allocation Tag Implementation Alright, I'm thinking about how the allocation tagging is handled within this specific memory management context. I need to take a close look at those line ranges: 590-620, 800-840, 850-1000, and 1340-1385. This suggests that the core mechanisms of the tag are probably in those areas. My initial thoughts are centering around what specific operations are happening around those areas. I'm expecting to find key functions or macros related to tagging operations. I'll need to identify how tags are associated with memory allocations and deallocations. What are the data structures used to store the tag information? Are there specific allocation routines that are modified to incorporate these tags, or is this implemented as a separate layer? I need to understand how the tag information is accessed and updated. I'm thinking that I'll need to trace the allocation flow. Specifically, I need to see how a request with a tag is handled, how it's mapped to the internal memory management structures, and how the tag is propagated through the system. Perhaps a quick scan will indicate if it's based on bitmaps, or linked lists, or some other method of keeping track. Also, the deallocation path will be critical: How are tags verified or utilized during freeing memory? Are there integrity checks related to the tags? And are there any performance implications of using tags - maybe some type of tagging overhead in the critical path? Ultimately, my goal is to fully grasp the implementation details of this tagging system. I want to have a good understanding of its performance and functional implications, and to ensure that I can identify potential issues. Let's start with those sections and see what we can find.
86/3	2026/09/15 07:47	tool	read-file	0m Args: { "File": "mm/alloc_tag.c", "FirstLine": 585, "LineCount": 40 } Results: { "Contents": " 585:\t\t/* swap tags /\n 586:\t\t__alloc_tag_ref_set(\u0026ref_old, tag_new);\n 587:\t\tupdate_page_tag_ref(handle_old, \u0026ref_old);\n 588:\t\t__alloc_tag_ref_set(\u0026ref_new, tag_old);\n 589:\t\tupdate_page_tag_ref(handle_new, \u0026ref_new);\n 590:\t\n 591:\t\tput_page_tag_ref(handle_old);\n 592:\t\tput_page_tag_ref(handle_new);\n 593:\t}\n 594:\t\n 595:\tstatic void remove_allocinfo_file(struct work_struct work)\n 596:\t{\n 597:\t\tremove_proc_entry(ALLOCINFO_FILE_NAME, NULL);\n 598:\t}\n 599:\t\n 600:\tstatic DECLARE_WORK(remove_allocinfo_work, remove_allocinfo_file);\n 601:\t\n 602:\tstatic void shutdown_mem_profiling(bool remove_file)\n 603:\t{\n 604:\t\tif (mem_alloc_profiling_enabled())\n 605:\t\t\tstatic_branch_disable(\u0026mem_alloc_profiling_key);\n 606:\t\n 607:\t\tif (!mem_profiling_support)\n 608:\t\t\treturn;\n 609:\t\n 610:\t\tif (remove_file)\n 611:\t\t\tschedule_work(\u0026remove_allocinfo_work);\n 612:\t\tmem_profiling_support = false;\n 613:\t}\n 614:\t\n 615:\tvoid __init alloc_tag_sec_init(void)\n 616:\t{\n 617:\t\tstruct alloc_tag *last_codetag;\n 618:\t\n 619:\t\tif (!mem_profiling_support)\n 620:\t\t\treturn;\n 621:\t\n 622:\t\tif (!static_key_enabled(\u0026mem_profiling_compressed))\n 623:\t\t\treturn;\n 624:\t\n" }
87/3	2026/09/15 07:47	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 26667 output: 35 thoughts: 33 Thoughts: Here's my summary, as though I'm thinking through this process: Diving into the Allocation Tagging Logic Alright, I need to get into the heart of how this memory allocator is tagging allocations. Based on the problem I'm seeing, I suspect something's off in how tags are being assigned or interpreted. My first move is to zero in on `mm/alloc_tag.c`. I remember this file handling a lot of the allocation tagging details, so it's the logical place to start digging. Specifically, I'm going to look closely at lines 800-850 and then again at lines 900-1010. These sections likely deal with the core mechanics of tag management – probably related to the allocation or deallocation events with tagging involved. This should give me a good understanding of what might be happening that I need to look into and solve.
88/3	2026/09/15 07:47	tool	read-file	0m Args: { "File": "mm/alloc_tag.c", "FirstLine": 805, "LineCount": 45 } Results: { "Contents": " 805:\t\t\t\tif (!allocated)\n 806:\t\t\t\t\tbreak;\n 807:\t\t\t\tnr += allocated;\n 808:\t\t\t}\n 809:\t\n 810:\t\t\tif (nr \u003c more_pages \|\|\n 811:\t\t\t vmap_pages_range(phys_end, phys_end + (nr \u003c\u003c PAGE_SHIFT), PAGE_KERNEL,\n 812:\t\t\t\t\t next_page, PAGE_SHIFT) \u003c 0) {\n 813:\t\t\t\trelease_pages_arg arg = { .pages = next_page };\n 814:\t\n 815:\t\t\t\t/\n 816:\t\t\t\t vmap_pages_range() only runs once all pages were\n 817:\t\t\t\t * allocated, and it may have installed some mappings\n 818:\t\t\t\t * before failing. Undo them.\n 819:\t\t\t\t /\n 820:\t\t\t\tif (nr == more_pages)\n 821:\t\t\t\t\tvunmap_range(phys_end, phys_end + (nr \u003c\u003c PAGE_SHIFT));\n 822:\t\t\t\t/ Clean up and error out /\n 823:\t\t\t\trelease_pages(arg, nr);\n 824:\t\t\t\treturn -ENOMEM;\n 825:\t\t\t}\n 826:\t\n 827:\t\t\tvm_module_tags-\u003enr_pages += nr;\n 828:\t\n 829:\t\t\t/\n 830:\t\t\t * Kasan allocates 1 byte of shadow for every 8 bytes of data.\n 831:\t\t\t * When kasan_alloc_module_shadow allocates shadow memory,\n 832:\t\t\t * its unit of allocation is a page.\n 833:\t\t\t * Therefore, here we need to align to MODULE_ALIGN.\n 834:\t\t\t /\n 835:\t\t\tif (old_shadow_end \u003c new_shadow_end)\n 836:\t\t\t\tkasan_alloc_module_shadow((void )old_shadow_end,\n 837:\t\t\t\t\t\t\t new_shadow_end - old_shadow_end,\n 838:\t\t\t\t\t\t\t GFP_KERNEL);\n 839:\t\t}\n 840:\t\n 841:\t\t/\n 842:\t\t Mark the pages as accessible, now that they are mapped.\n 843:\t\t * With hardware tag-based KASAN, marking is skipped for\n 844:\t\t * non-VM_ALLOC mappings, see __kasan_unpoison_vmalloc().\n 845:\t\t /\n 846:\t\tkasan_unpoison_vmalloc((void )module_tags.start_addr,\n 847:\t\t\t\t\tnew_end - module_tags.start_addr,\n 848:\t\t\t\t\tKASAN_VMALLOC_PROT_NORMAL);\n 849:\t\n" }
89/3	2026/09/15 07:47	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 27623 output: 35 thoughts: 24 Thoughts: Here's my take on the thought process, summarized as you requested: Digging into the Allocation Tagging Okay, so I'm trying to track down this memory allocation issue, and I've got a hunch it's related to how we're tagging memory. Time to dive into `mm/alloc_tag.c`. My gut says the problem might be around the 900-1010 line range. I need to refresh my memory on how the tagging mechanism actually works there - what the data structures look like, how we're assigning tags, and any potential race conditions that might be lurking. I'll focus on that section to see if anything jumps out as problematic or if I can spot any obvious logic errors. Let's see what's there...
90/3	2026/09/15 07:47	tool	read-file	0m Args: { "File": "mm/alloc_tag.c", "FirstLine": 950, "LineCount": 60 } Results: { "Contents": " 950:\t\t\t\tret = ERR_PTR(xa_err(mas.node));\n 951:\t\t\t}\n 952:\t\t} else {\n 953:\t\t\tmas.last = offset + size - 1;\n 954:\t\t\tmas_store(\u0026mas, mod);\n 955:\t\t\tif (mas_is_err(\u0026mas))\n 956:\t\t\t\tret = ERR_PTR(xa_err(mas.node));\n 957:\t\t}\n 958:\tunlock:\n 959:\t\tmas_unlock(\u0026mas);\n 960:\t\n 961:\t\tif (IS_ERR(ret))\n 962:\t\t\treturn ret;\n 963:\t\n 964:\t\tif (module_tags.size \u003c offset + size) {\n 965:\t\t\tunsigned long prev_size = module_tags.size;\n 966:\t\t\tint grow_res;\n 967:\t\n 968:\t\t\tmodule_tags.size = offset + size;\n 969:\t\t\tif (!tags_addressable()) {\n 970:\t\t\t\tshutdown_mem_profiling(true);\n 971:\t\t\t\tpr_warn_once(\"With module %s there are too many tags to fit in %d page flag bits. Memory allocation profiling is disabled!\\n\",\n 972:\t\t\t\t\t mod-\u003ename, NR_UNUSED_PAGEFLAG_BITS);\n 973:\t\t\t\trelease_module_tags(mod, false);\n 974:\t\t\t\tmodule_tags.size = prev_size;\n 975:\t\t\t\treturn ERR_PTR(-EAGAIN);\n 976:\t\t\t}\n 977:\t\n 978:\t\t\tgrow_res = vm_module_tags_populate();\n 979:\t\t\tif (grow_res) {\n 980:\t\t\t\tshutdown_mem_profiling(true);\n 981:\t\t\t\tpr_err(\"Failed to allocate memory for allocation tags in the module %s. Memory allocation profiling is disabled!\\n\",\n 982:\t\t\t\t mod-\u003ename);\n 983:\t\t\t\trelease_module_tags(mod, false);\n 984:\t\t\t\tmodule_tags.size = prev_size;\n 985:\t\t\t\treturn ERR_PTR(grow_res);\n 986:\t\t\t}\n 987:\t\t}\n 988:\t\n 989:\t\treturn (struct alloc_tag )(module_tags.start_addr + offset);\n 990:\t}\n 991:\t\n 992:\tstatic int load_module(struct module mod, struct codetag start, struct codetag stop)\n 993:\t{\n 994:\t\t/* Allocate module alloc_tag percpu counters /\n 995:\t\tstruct alloc_tag start_tag;\n 996:\t\tstruct alloc_tag stop_tag;\n 997:\t\tstruct alloc_tag tag;\n 998:\t\n 999:\t\t/* Profiling disabled: load the module without its tags. /\n1000:\t\tif (!mem_profiling_support)\n1001:\t\t\treturn -EOPNOTSUPP;\n1002:\t\n1003:\t\t/ percpu counters for core allocations are already statically allocated */\n1004:\t\tif (!mod)\n1005:\t\t\treturn 0;\n1006:\t\n1007:\t\tstart_tag = ct_to_alloc_tag(start);\n1008:\t\tstop_tag = ct_to_alloc_tag(stop);\n1009:\t\tfor (tag = start_tag; tag \u003c stop_tag; tag++) {\n" }
91/3	2026/09/15 07:47	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 28758 output: 36 thoughts: 23 Thoughts: Here's my take on that code snippet: Diving Deeper into `mm/alloc_tag.c` Okay, so I've been focusing on `load_module` in `mm/alloc_tag.c` recently, but I need to expand my understanding of its context. It's time to thoroughly examine exactly what `load_module` is doing within the broader framework of this file. I need to understand how it interacts with the allocation tagging mechanism and what impact it has on memory management, especially in dynamic scenarios. I also want to assess if this function is behaving correctly or if I can improve its performance. I'll need to look at adjacent functions and the overall data structures it affects to get a complete picture. Let's see what more this code has to tell me.
92/3	2026/09/15 07:47	tool	read-file	0m Args: { "File": "mm/alloc_tag.c", "FirstLine": 1008, "LineCount": 40 } Results: { "Contents": "1008:\t\tstop_tag = ct_to_alloc_tag(stop);\n1009:\t\tfor (tag = start_tag; tag \u003c stop_tag; tag++) {\n1010:\t\t\tWARN_ON(tag-\u003ecounters);\n1011:\t\t\ttag-\u003ecounters = alloc_percpu(struct alloc_tag_counters);\n1012:\t\t\tif (!tag-\u003ecounters) {\n1013:\t\t\t\twhile (--tag \u003e= start_tag) {\n1014:\t\t\t\t\tfree_percpu(tag-\u003ecounters);\n1015:\t\t\t\t\ttag-\u003ecounters = NULL;\n1016:\t\t\t\t}\n1017:\t\t\t\tpr_err(\"Failed to allocate memory for allocation tag percpu counters in the module %s\\n\",\n1018:\t\t\t\t mod-\u003ename);\n1019:\t\t\t\treturn -ENOMEM;\n1020:\t\t\t}\n1021:\t\n1022:\t\t\t/\n1023:\t\t\t Avoid a kmemleak false positive. The pointer to the counters is stored\n1024:\t\t\t * in the alloc_tag section of the module and cannot be directly accessed.\n1025:\t\t\t /\n1026:\t\t\tkmemleak_ignore_percpu(tag-\u003ecounters);\n1027:\t\t}\n1028:\t\treturn 0;\n1029:\t}\n1030:\t\n1031:\tstatic void replace_module(struct module mod, struct module new_mod)\n1032:\t{\n1033:\t\tMA_STATE(mas, \u0026mod_area_mt, 0, module_tags.size);\n1034:\t\tstruct module val;\n1035:\t\n1036:\t\tmas_lock(\u0026mas);\n1037:\t\tmas_for_each(\u0026mas, val, module_tags.size) {\n1038:\t\t\tif (val != mod)\n1039:\t\t\t\tcontinue;\n1040:\t\n1041:\t\t\tmas_store_gfp(\u0026mas, new_mod, GFP_KERNEL);\n1042:\t\t\tbreak;\n1043:\t\t}\n1044:\t\tmas_unlock(\u0026mas);\n1045:\t}\n1046:\t\n1047:\tstatic int __init alloc_mod_tags_mem(void)\n" }
93/3	2026/09/15 07:47	llm	kmsan-evaluator	1m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 29574 output: 35 thoughts: 1028 Thoughts: Analyzing Module Loading with Conditional Codetag Allocation Okay, let's break this down step-by-step. My initial thought is about what happens if `tags_addressable()` returns false in `reserve_module_tags`. That function call is key because it leads to the crucial allocation within `codetag_alloc_module_section`. This is used via `codetag_alloc_module_section(info->mod, sname, shdr->sh_size, arch_mod_section_prepend(info->mod, i), shdr->sh_addralign)`, which is part of the `allocate_codetag_sections` process. Here's the interesting bit: if `dest` from that call ends up being `ERR_PTR(-EAGAIN)`, the code `continue`s! My curiosity is piqued. What's the state of `shdr->sh_entsize` at this point? Diving in, I remember that `shdr->sh_entsize` is initialized to `~0UL` in `layout_and_allocate` within this loop: `for (i = 0; i < info->hdr->e_shnum; i++) info->sechdrs[i].sh_entsize = ~0UL;`. This means that `shdr->sh_entsize` stays at `~0UL`, and `shdr->sh_addr` maintains its temporary image address. Then, during `layout_sections`, I hit another critical check: ```c if ((s->sh_flags & masks[m][0]) != masks[m][0] \|\| (s->sh_flags & masks[m][1]) \|\| s->sh_entsize != ~0UL /* offset or standalone / \|\| is_init != module_init_layout_section(sname)) continue; ``` Because `s->sh_entsize` is* `~0UL`, it passes this check, and the section is treated as a regular section. This means that `s->sh_entsize = module_get_offset_and_type(...)` is called, and that assigns an offset and type in `mod->mem[type]`. Then, during `move_module`, the section is copied into the `mod->mem[type].base + offset` memory. Next, when it gets to codetag initialization (`codetag_load_module`), if the codetag section loading is skipped, `load_module` will see `!mem_profiling_support` and return `-EOPNOTSUPP`. However, `codetag_module_init` handles the error: `if (err != -EOPNOTSUPP) return err; return 0;` meaning that the module loads successfully without allocation profiling. Alright, let's switch gears. I need to make sure this patch isn't causing any issues with kernel structures that are sent to user space. It's a critical review to prevent uninitialized data leaks via any user-facing interfaces. I'll focus on `copy_to_user`, `put_user`, netlink skb attributes, ioctl output arguments, socket options, or BPF buffers. Time to check sysfs and /proc! Wait a moment! `kernel/module/sysfs.c` has been touched, specifically with the addition of `sect_visible`: ```c static bool sect_visible(const struct load_info info, unsigned int i) { return !sect_empty(&info->sechdrs[i]) && i != info->index.pcpu; } ``` What was sysfs doing before* this patch? I need to understand the baseline. Looking at the existing code in `add_sect_attrs` and `add_notes_attrs`, I see that the code iterates through sections and uses `sect_visible` to select sections and it counts loaded sections. Most importantly, it allocates the structures using `kzalloc_flex`! That's good, because `kzalloc_flex` zeroes the memory it allocates. The only exclusion is `info->index.pcpu`. Ok, so now, let's review the whole of `add_sect_attrs` to make sure nothing is missed!
94/3	2026/09/15 07:49	tool	read-file	0m Args: { "File": "kernel/module/sysfs.c", "FirstLine": 70, "LineCount": 60 } Results: { "Contents": " 70:\t{\n 71:\t\treturn !sect_empty(\u0026info-\u003esechdrs[i]) \u0026\u0026 i != info-\u003eindex.pcpu;\n 72:\t}\n 73:\t\n 74:\tstatic int add_sect_attrs(struct module mod, const struct load_info info)\n 75:\t{\n 76:\t\tstruct module_sect_attrs sect_attrs;\n 77:\t\tconst struct bin_attribute gattr;\n 78:\t\tstruct bin_attribute sattr;\n 79:\t\tunsigned int nloaded = 0, i;\n 80:\t\tint ret;\n 81:\t\n 82:\t\t/* Count loaded sections and allocate structures /\n 83:\t\tfor (i = 0; i \u003c info-\u003ehdr-\u003ee_shnum; i++)\n 84:\t\t\tif (sect_visible(info, i))\n 85:\t\t\t\tnloaded++;\n 86:\t\tsect_attrs = kzalloc_flex(sect_attrs, attrs, nloaded);\n 87:\t\tif (!sect_attrs)\n 88:\t\t\treturn -ENOMEM;\n 89:\t\n 90:\t\tgattr = kzalloc_objs(gattr, nloaded + 1);\n 91:\t\tif (!gattr) {\n 92:\t\t\tkfree(sect_attrs);\n 93:\t\t\treturn -ENOMEM;\n 94:\t\t}\n 95:\t\n 96:\t\t/ Setup section attributes. /\n 97:\t\tsect_attrs-\u003egrp.name = \"sections\";\n 98:\t\tsect_attrs-\u003egrp.bin_attrs = gattr;\n 99:\t\n 100:\t\tsattr = \u0026sect_attrs-\u003eattrs[0];\n 101:\t\tfor (i = 0; i \u003c info-\u003ehdr-\u003ee_shnum; i++) {\n 102:\t\t\tElf_Shdr sec = \u0026info-\u003esechdrs[i];\n 103:\t\n 104:\t\t\tif (!sect_visible(info, i))\n 105:\t\t\t\tcontinue;\n 106:\t\t\tsysfs_bin_attr_init(sattr);\n 107:\t\t\tsattr-\u003eattr.name =\n 108:\t\t\t\tkstrdup(info-\u003esecstrings + sec-\u003esh_name, GFP_KERNEL);\n 109:\t\t\tif (!sattr-\u003eattr.name) {\n 110:\t\t\t\tret = -ENOMEM;\n 111:\t\t\t\tgoto out;\n 112:\t\t\t}\n 113:\t\t\tsattr-\u003eread = module_sect_read;\n 114:\t\t\tsattr-\u003eprivate = (void )sec-\u003esh_addr;\n 115:\t\t\tsattr-\u003esize = MODULE_SECT_READ_SIZE;\n 116:\t\t\tsattr-\u003eattr.mode = 0400;\n 117:\t\t\t(gattr++) = sattr++;\n 118:\t\t}\n 119:\t\n 120:\t\tret = sysfs_create_group(\u0026mod-\u003emkobj.kobj, \u0026sect_attrs-\u003egrp);\n 121:\t\tif (ret)\n 122:\t\t\tgoto out;\n 123:\t\n 124:\t\tmod-\u003esect_attrs = sect_attrs;\n 125:\t\treturn 0;\n 126:\tout:\n 127:\t\tfree_sect_attrs(sect_attrs);\n 128:\t\treturn ret;\n 129:\t}\n" }
95/3	2026/09/15 07:49	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 32441 output: 36 thoughts: 54 Thoughts: Here's my summary, as the expert: Investigating Memory Allocation in Attribute Addition Functions Okay, let's dive into this. I'm focusing on the allocation strategy within the `add_sect_attrs` function. I see the use of `kzalloc_flex` and `kzalloc_objs` here, and that immediately tells me these are zeroed memory allocations, which is a key design consideration. I'm wondering if this pattern is consistent across related functions, specifically `add_notes_attrs`. Time to check that function and see what it's doing with memory.
96/3	2026/09/15 07:49	tool	read-file	0m Args: { "File": "kernel/module/sysfs.c", "FirstLine": 160, "LineCount": 60 } Results: { "Contents": " 160:\tstatic int add_notes_attrs(struct module mod, const struct load_info info)\n 161:\t{\n 162:\t\tunsigned int notes, loaded, i;\n 163:\t\tstruct module_notes_attrs notes_attrs;\n 164:\t\tconst struct bin_attribute gattr;\n 165:\t\tstruct bin_attribute nattr;\n 166:\t\tint ret;\n 167:\t\n 168:\t\t/* Count notes sections and allocate structures. /\n 169:\t\tnotes = 0;\n 170:\t\tfor (i = 0; i \u003c info-\u003ehdr-\u003ee_shnum; i++)\n 171:\t\t\tif (sect_visible(info, i) \u0026\u0026\n 172:\t\t\t info-\u003esechdrs[i].sh_type == SHT_NOTE)\n 173:\t\t\t\t++notes;\n 174:\t\n 175:\t\tif (notes == 0)\n 176:\t\t\treturn 0;\n 177:\t\n 178:\t\tnotes_attrs = kzalloc_flex(notes_attrs, attrs, notes);\n 179:\t\tif (!notes_attrs)\n 180:\t\t\treturn -ENOMEM;\n 181:\t\n 182:\t\tgattr = kzalloc_objs(gattr, notes + 1);\n 183:\t\tif (!gattr) {\n 184:\t\t\tkfree(notes_attrs);\n 185:\t\t\treturn -ENOMEM;\n 186:\t\t}\n 187:\t\n 188:\t\tnotes_attrs-\u003egrp.name = \"notes\";\n 189:\t\tnotes_attrs-\u003egrp.bin_attrs = gattr;\n 190:\t\n 191:\t\tnattr = \u0026notes_attrs-\u003eattrs[0];\n 192:\t\tfor (loaded = i = 0; i \u003c info-\u003ehdr-\u003ee_shnum; ++i) {\n 193:\t\t\tif (!sect_visible(info, i))\n 194:\t\t\t\tcontinue;\n 195:\t\t\tif (info-\u003esechdrs[i].sh_type == SHT_NOTE) {\n 196:\t\t\t\tsysfs_bin_attr_init(nattr);\n 197:\t\t\t\tnattr-\u003eattr.name = mod-\u003esect_attrs-\u003eattrs[loaded].attr.name;\n 198:\t\t\t\tnattr-\u003eattr.mode = 0444;\n 199:\t\t\t\tnattr-\u003esize = info-\u003esechdrs[i].sh_size;\n 200:\t\t\t\tnattr-\u003eprivate = (void )info-\u003esechdrs[i].sh_addr;\n 201:\t\t\t\tnattr-\u003eread = sysfs_bin_attr_simple_read;\n 202:\t\t\t\t(gattr++) = nattr++;\n 203:\t\t\t}\n 204:\t\t\t++loaded;\n 205:\t\t}\n 206:\t\n 207:\t\tret = sysfs_create_group(\u0026mod-\u003emkobj.kobj, \u0026notes_attrs-\u003egrp);\n 208:\t\tif (ret)\n 209:\t\t\tgoto out;\n 210:\t\n 211:\t\tmod-\u003enotes_attrs = notes_attrs;\n 212:\t\treturn 0;\n 213:\t\n 214:\tout:\n 215:\t\tfree_notes_attrs(notes_attrs);\n 216:\t\treturn ret;\n 217:\t}\n 218:\t\n 219:\tstatic void remove_notes_attrs(struct module mod)\n" }
97/3	2026/09/15 07:49	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 33576 output: 29 thoughts: 1190 Thoughts: Analyzing the Memory Layout and Relocation Logic Okay, so I'm looking at this code and immediately I see `notes_attrs = kzalloc_flex(notes_attrs, attrs, notes);` and `gattr = kzalloc_objs(gattr, notes + 1);` which are both zeroed, which makes sense. I have to wonder if these zero-initializations are covering all the bases. Then my mind jumps to `allocate_codetag_sections`. I have to check that function. Ah, here it is: the critical bit, if `shdr->sh_type != SHT_NOBITS` it copies data using `memcpy` from the address stored in the temporary elf image into `dest`. Otherwise, if it's `SHT_NOBITS`, it does a `memset` to zero it. This seems different from previous versions. I need to understand what changed. Where was this copying done previously? I dig up the old code and I find it! In the `move_module` function. It looks like codetag section memory was both allocated and copied within that function. Now, in this new version, the allocation and copying happens earlier in `allocate_codetag_sections`, before the `layout_sections` phase. This also means that, if it's a `SHT_NOBITS` section it explicitly zeros it, which is something the old code in `move_module` didn't do for codetag sections, since codetag sections are usually `SHT_PROGBITS`. Now, the next thing that springs to mind: Relocations! Time to look at `apply_relocations` in `main.c`. Okay, here's the crucial section: ```c for (i = 1; i < info->hdr->e_shnum; i++) { unsigned int infosec = info->sechdrs[i].sh_info; /* Not a valid section we want to apply relocations for / if (infosec >= info->hdr->e_shnum) continue; / * Don't bother with non-allocated sections. * * Note that .data..percpu has separate allocations for * individual CPUs. We relocate the section in the * initial ELF template and subsequently copy it to the * per-CPU destinations. */ if (!(info->sechdrs[infosec].sh_flags & SHF_ALLOC)) continue; ``` I remember the old code! I've got it. I'm digging into it. It used to be different: ```c if (!(info->sechdrs[infosec].sh_flags & SHF_ALLOC) && (!infosec \|\| infosec != info->index.pcpu)) continue; ``` Aha! I see it! The old code had `(!infosec \|\| infosec != info->index.pcpu)`. Why? Because `layout_and_allocate` used to clear `SHF_ALLOC` from `info->sechdrs[info->index.pcpu].sh_flags`! That's why it needed that special case. But now, in the new version, `layout_and_allocate` NO LONGER clears `SHF_ALLOC` from `info->sechdrs[info->index.pcpu].sh_flags`. So now `info->sechdrs[info->index.pcpu].sh_flags & SHF_ALLOC` is true, which makes the old exception redundant and it was simplified. Okay, so I am going to have to make sure that this means no regressions on the relocations for the codetag sections! Do codetag sections have `SHF_ALLOC`? Yes, they are allocated. Now where are they relocated? Wait, when `allocate_codetag_sections` is called, `shdr->sh_addr = (unsigned long)dest;` is set. Okay, I need to check when `apply_relocations` is called relative to `layout_and_allocate`.
98/3	2026/09/15 07:50	tool	grepper	0m Args: { "Expression": "apply_relocations", "PathPrefix": "kernel/module/" } Results: { "Output": "kernel/module/main.c=1529=static int simplify_symbols(struct module mod, const struct load_info info)\n--\nkernel/module/main.c-1606-\nkernel/module/main.c:1607:static int apply_relocations(struct module mod, const struct load_info info)\nkernel/module/main.c-1608-{\n--\nkernel/module/main.c=3442=static int load_module(struct load_info info, const char __user uargs,\n--\nkernel/module/main.c-3534-\nkernel/module/main.c:3535:\terr = apply_relocations(mod, info);\nkernel/module/main.c-3536-\tif (err \u003c 0)\n" }
99/3	2026/09/15 07:50	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 35907 output: 29 thoughts: 21 Thoughts: Here's my summary, as if I were thinking it: Tracing the Module Loading Process Okay, so I'm diving into the module loading code again. Time to refresh my memory and pinpoint the critical path. Let's see: `load_module`, that's the main entry point, and it's calling `layout_and_allocate` as a subroutine at a specific line. This is the stage where the module's structure is being defined in memory, and space is set aside for the code and data. Knowing this interaction is key to understanding how modules are brought into the system. Need to see how that allocation works to understand the underlying memory management and potentially pinpoint any performance bottlenecks.
100/3	2026/09/15 07:50	tool	grepper	0m Args: { "Expression": "layout_and_allocate", "PathPrefix": "kernel/module/" } Results: { "Output": "kernel/module/internal.h=164=static inline bool set_livepatch_module(struct module mod)\n--\nkernel/module/internal.h-179- \tor being processed on our \u0026modules list. This happens on early_mod_check()\nkernel/module/internal.h:180: * \tright before layout_and_allocate(). The kernel would have already\nkernel/module/internal.h-181- * \tvmalloc()'d space for the entire module through finit_module(). If\n--\nkernel/module/internal.h-187- \tof this allocated yet another private kernel copy of the module space in\nkernel/module/internal.h:188: \tlayout_and_allocate() but after this determined in add_unformed_module()\nkernel/module/internal.h-189- \tthat another module with the same name is already loaded or being processed.\n--\nkernel/module/main.c=2919=static int allocate_codetag_sections(struct load_info info)\n--\nkernel/module/main.c-2953-\nkernel/module/main.c:2954:static struct module layout_and_allocate(struct load_info info, int flags)\nkernel/module/main.c-2955-{\n--\nkernel/module/main.c=3442=static int load_module(struct load_info info, const char __user uargs,\n--\nkernel/module/main.c-3479-\t/* Figure out module layout, and allocate all the memory. /\nkernel/module/main.c:3480:\tmod = layout_and_allocate(info, flags);\nkernel/module/main.c-3481-\tif (IS_ERR(mod)) {\n--\nkernel/module/stats.c-42- from kernel_read_file_from_fd() is freed right away.\nkernel/module/stats.c:43: * c) layout_and_allocate() allocates space for the final resting\nkernel/module/stats.c-44- * place where we would keep the module if it were to be processed\n--\nkernel/module/stats.c-88- * a) FAIL_DUP_MOD_BECOMING: at the end of early_mod_check() before\nkernel/module/stats.c:89: \tlayout_and_allocate().\nkernel/module/stats.c-90- \t- with module decompression: 2 virtual memory allocation calls\nkernel/module/stats.c-91- \t- without module decompression: 1 virtual memory allocation calls\nkernel/module/stats.c:92: b) FAIL_DUP_MOD_LOAD: after layout_and_allocate() on add_unformed_module()\nkernel/module/stats.c-93- * \t- with module decompression 3 virtual memory allocation calls\n--\nkernel/module/stats.c=100=static LIST_HEAD(dup_failed_modules);\n--\nkernel/module/stats.c-139- * at the end of early_mod_check() prevents duplicate allocations\nkernel/module/stats.c:140: * on layout_and_allocate() for modules already being processed. These\nkernel/module/stats.c-141- * duplicate failed modules are non-fatal, however they typically are\n--\nkernel/module/stats.c-166- * is unique. A module can still fail to load if we detect the module is\nkernel/module/stats.c:167: * loaded after we allocate space for it with layout_and_allocate(), we do\nkernel/module/stats.c-168- * this check right before processing the module as live and run its\n--\nkernel/module/stats.c-180- * * failed_becoming: how many modules failed after we kernel_read_file_from_fd()\nkernel/module/stats.c:181: * it and before we allocate memory for it with layout_and_allocate(). This\nkernel/module/stats.c-182- * counter is never incremented if you manage to validate the module and\nkernel/module/stats.c:183: * call layout_and_allocate() for it.\nkernel/module/stats.c-184- * * failed_load_modules: how many modules failed once we've allocated our\nkernel/module/stats.c:185: * private space for our module using layout_and_allocate(). These failures\nkernel/module/stats.c-186- * should hopefully mostly be dealt with already. Races in theory could\n" }
101/3	2026/09/15 07:50	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 37221 output: 29 thoughts: 988 Thoughts: Analyzing the Module Loading Patch: A Deep Dive Okay, so I'm looking at this module loading patch, and I need to understand its impact, especially in relation to potential KMSAN issues. First, the sequence of events is clear: `layout_and_allocate` is invoked at a specific point, and then `apply_relocations` happens later. Crucially, the section header address (`shdr->sh_addr`) is updated during `layout_and_allocate`, both before and after this patch. The relocation application remains a separate stage. This suggests the fundamental module loading workflow hasn't changed drastically in terms of when these core operations occur, but how they're performed might have. Now, let's break down the fixes this patch series introduces. The first one deals with codetag section allocation. The previous behavior was to hard-fail the module load if codetag allocation failed, whereas now we have a graceful fallback: If the codetag allocation overflows, it falls back to a regular section allocation within the module. This involves handling `-EAGAIN` in a couple of places. The logic ensures that even if codetag memory allocation is problematic, the module still tries to load (with a potential performance impact and without codetags). We should confirm how this is reflected in the KMSAN check. The `-EOPNOTSUPP` handling in `codetag_module_init` seems important here: it allows the module to load without its tags. This is a significant change in the error handling. The second fix relates to `alloc_tag.c` and addresses a potential deadlock or invalid context issue when calling `remove_proc_entry` synchronously. The patch now uses `schedule_work` to defer this operation, making it asynchronous, which is good. Additionally, a memory leak or unmap issue is addressed in `vm_module_tags_populate()` (fixes an issue with `vunmap_range` on failure), and `proc_create` call ordering is changed to be after the memory is reserved. These are more general stability fixes, but we should make sure this doesn't lead to issues further down the line with KMSAN. The third change pertains to percpu section handling. This is where things get interesting. Previously, `.data..percpu` sections were marked with `SHF_ALLOC` cleared. This meant that `apply_relocations` had a specific check to handle this. Now, `SHF_ALLOC` is not cleared. Instead, `sh_entsize` is set to `SH_ENTSIZE_STANDALONE`. This change essentially hides the section from being relocated by `__layout_sections` and `move_module`, and filters it out in `sysfs.c`, where section visibility is controlled. This implies a fundamental change in how percpu sections are treated during module loading. The rationale behind this change is an important factor. Now the million-dollar question: Does this patch introduce anything that might trigger a KMSAN violation? I need to focus on my four main criteria. My primary concern here revolves around any data sent to user space where fields might not be initialized. My suspicion here stems from the `sysfs.c` modification, namely the reading of section addresses in `module_sect_read`, as the patch has changes affecting section visibility and how the sections are handled internally. Let's dig deeper into that function and its calling context. Is the formatting process susceptible to uninitialized memory, especially given the new `SH_ENTSIZE_STANDALONE` handling for percpu sections? We need to verify if the address retrieval process in `module_sect_read` is robust enough to handle the potential for uninitialized data or incorrect assumptions about section data. This is where I'll put my focus, with consideration for how percpu sections are excluded.
102/3	2026/09/15 07:51	tool	grepper	0m Args: { "Expression": "module_sect_read", "PathPrefix": "kernel/module/" } Results: { "Output": "kernel/module/sysfs.c=22=struct module_sect_attrs {\n--\nkernel/module/sysfs.c-27-#define MODULE_SECT_READ_SIZE (3 /* \"0x\", \"\\n\" / + (BITS_PER_LONG / 4))\nkernel/module/sysfs.c:28:static ssize_t module_sect_read(struct file file, struct kobject kobj,\nkernel/module/sysfs.c-29-\t\t\t\tconst struct bin_attribute battr,\n--\nkernel/module/sysfs.c=74=static int add_sect_attrs(struct module mod, const struct load_info info)\n--\nkernel/module/sysfs.c-112-\t\t}\nkernel/module/sysfs.c:113:\t\tsattr-\u003eread = module_sect_read;\nkernel/module/sysfs.c-114-\t\tsattr-\u003eprivate = (void *)sec-\u003esh_addr;\n" }
103/3	2026/09/15 07:51	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 39306 output: 35 thoughts: 22 Thoughts: Here's my take on the thought process, as if it were my own: Investigating `module_sect_read` in `kernel/module/sysfs.c` Okay, time to dive into this. I need to refresh my memory on the inner workings of module section reading within the kernel, specifically focusing on how it interacts with sysfs. The function I'm targeting is `module_sect_read` and it's located in `kernel/module/sysfs.c`. I expect this function plays a crucial role in providing access to module sections through the sysfs interface. I need to understand the data flow, access control, potential race conditions, and error handling involved. I'm going to look for any potential vulnerabilities, or performance bottlenecks. I need to be able to answer any question that can be brought to bear regarding this function, as well as the functionality that's dependent on it. So, let's open that file and get started.
104/3	2026/09/15 07:51	tool	read-file	0m Args: { "File": "kernel/module/sysfs.c", "FirstLine": 25, "LineCount": 25 } Results: { "Contents": " 25:\t};\n 26:\t\n 27:\t#define MODULE_SECT_READ_SIZE (3 /* \"0x\", \"\\n\" / + (BITS_PER_LONG / 4))\n 28:\tstatic ssize_t module_sect_read(struct file file, struct kobject kobj,\n 29:\t\t\t\t\tconst struct bin_attribute battr,\n 30:\t\t\t\t\tchar buf, loff_t pos, size_t count)\n 31:\t{\n 32:\t\tchar bounce[MODULE_SECT_READ_SIZE + 1];\n 33:\t\tsize_t wrote;\n 34:\t\n 35:\t\tif (pos != 0)\n 36:\t\t\treturn -EINVAL;\n 37:\t\n 38:\t\t/\n 39:\t\t * Since we're a binary read handler, we must account for the\n 40:\t\t * trailing NUL byte that sprintf will write: if \"buf\" is\n 41:\t\t * too small to hold the NUL, or the NUL is exactly the last\n 42:\t\t * byte, the read will look like it got truncated by one byte.\n 43:\t\t * Since there is no way to ask sprintf nicely to not write\n 44:\t\t * the NUL, we have to use a bounce buffer.\n 45:\t\t */\n 46:\t\twrote = scnprintf(bounce, sizeof(bounce), \"0x%px\\n\",\n 47:\t\t\t\t kallsyms_show_value(file-\u003ef_cred)\n 48:\t\t\t\t\t? battr-\u003eprivate : NULL);\n 49:\t\tcount = min(count, wrote);\n" }
105/3	2026/09/15 07:51	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 39986 output: 34 thoughts: 1810 Thoughts: Code Review: Addressing Potential Uninitialized Data Concerns Okay, let's break this down. First, the code uses `scnprintf` and `memcpy`, and while I don't see any obvious direct use of uninitialized data in those specific functions, I need to look deeper into how those functions are used in the broader context. Also, regarding the changes to `sect_visible`, it seems the change in logic from `!sect_empty(...)` to an explicit check with an additional condition doesn't introduce any functional change regarding sysfs section attributes, which is good. The behavior should be identical. Now, on to Criterion 2: "Conditional logic or branching that depends on potentially uninitialized variables or struct fields." I'm systematically going through the variables in the diff. * In `allocate_codetag_sections`, I've verified that all variables used in conditions are initialized before use. `dest` is either assigned a return value, or a value from a structure. There's good error handling with `WARN_ON`, `ERR_PTR`, and `IS_ERR` checks, and the `memcpy` or `memset` operations ensure `dest` is always initialized. * In `layout_and_allocate`, the `i` variable is properly initialized. * In `mm/alloc_tag.c`, the `remove_allocinfo_file` work function and `vm_module_tags_populate` work as expected. * The `reserve_module_tags` and `load_module` functions also look good with properly initialized variables. So far, it looks clean regarding Criterion 2, but I need to be thorough. Moving on to Criterion 3: "Allocation or initialization of complex data structures where uninitialized fields could be read later in reachable code paths." I need to revisit `allocate_codetag_sections` again. In the case where `allocate_codetag_sections` allocates a standalone codetag section, `dest` is fully written with either `memcpy` or `memset` depending on the section type. Even when `dest == ERR_PTR(-EAGAIN)`, `shdr->sh_entsize` is initialized to `~0UL` and `shdr->sh_addr` is set. Then, in the fallback path, `__layout_sections` correctly handles the case where `s->sh_entsize == ~0UL`, calls `module_get_offset_and_type`, and then `move_module`, properly initializing it. So it seems like this is ok. The `memcpy` or zeroing operations happen after allocation, so this is good. Finally, Criterion 4: "Bounds checks, lengths, or logic in a way that allows surrounding code to access uninitialized bytes of existing buffers." I'm looking for any changes in bounds checks or length logic that could cause uninitialized bytes to be accessed. In `layout_symtab` and `add_kallsyms`, the loop that calculates the total size of `strtab` seems safe. The `strlen` is on a string in a correctly populated data structure. In `is_core_symbol`, the checks on `sec->sh_flags` and the `type` derived from `sh_entsize` look reasonable. Wait, the `type` derivation needs a second look, especially with the bit shifts and masks... `SH_ENTSIZE_STANDALONE` seems to be related to the section type. So `type` is assigned `((unsigned long)MOD_STANDALONE & SH_ENTSIZE_TYPE_MASK)`. Let me verify `SH_ENTSIZE_TYPE_MASK` and `SH_ENTSIZE_TYPE_BITS` by checking `kernel/module/internal.h`. The goal here is to make sure we're not inadvertently revealing the contents of uninitialized variables in our bitmasking operations. If these constants are correctly defined, then the logic is sound. After that check, I can say with confidence that the bounds checks and length logic are solid.
106/3	2026/09/15 07:51	tool	read-file	0m Args: { "File": "kernel/module/internal.h", "FirstLine": 15, "LineCount": 35 } Results: { "Contents": " 15:\t#include \u003clinux/mm.h\u003e\n 16:\t\n 17:\t#ifndef ARCH_SHF_SMALL\n 18:\t#define ARCH_SHF_SMALL 0\n 19:\t#endif\n 20:\t\n 21:\t/\n 22:\t Use highest 4 bits of sh_entsize to store the mod_mem_type of this\n 23:\t * section. This leaves 28 bits for offset on 32-bit systems, which is\n 24:\t * about 256 MiB (WARN_ON_ONCE if we exceed that).\n 25:\t /\n 26:\t\n 27:\t#define SH_ENTSIZE_TYPE_BITS\t4\n 28:\t#define SH_ENTSIZE_TYPE_SHIFT\t(BITS_PER_LONG - SH_ENTSIZE_TYPE_BITS)\n 29:\t#define SH_ENTSIZE_TYPE_MASK\t((1UL \u003c\u003c SH_ENTSIZE_TYPE_BITS) - 1)\n 30:\t#define SH_ENTSIZE_OFFSET_MASK\t((1UL \u003c\u003c (BITS_PER_LONG - SH_ENTSIZE_TYPE_BITS)) - 1)\n 31:\t\n 32:\t/\n 33:\t * Marker for sections with a separate allocation, which are not placed\n 34:\t * into mod-\u003emem[].\n 35:\t /\n 36:\t#define SH_ENTSIZE_STANDALONE\t\t\t\t\t\\\n 37:\t\t(((unsigned long)MOD_STANDALONE \u0026 SH_ENTSIZE_TYPE_MASK)\t\\\n 38:\t\t \u003c\u003c SH_ENTSIZE_TYPE_SHIFT)\n 39:\t\n 40:\t/ Maximum number of characters written by module_flags() */\n 41:\t#define MODULE_FLAGS_BUF_SIZE (TAINT_FLAGS_COUNT + 4)\n 42:\t\n 43:\tstruct kernel_symbol {\n 44:\t#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS\n 45:\t\tint value_offset;\n 46:\t\tint name_offset;\n 47:\t\tint namespace_offset;\n 48:\t#else\n 49:\t\tunsigned long value;\n" }
107/3	2026/09/15 07:51	llm	kmsan-evaluator	1m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 43247 output: 36 thoughts: 330 Thoughts: Analyzing `mod_mem_type_is_init` and Its Implications Okay, let's break this down. I'm looking at this `mod_mem_type_is_init(type)` macro, specifically the implementation: ```c #define mod_mem_type_is_init(type) \ ((type) == MOD_INIT_TEXT \|\| \ (type) == MOD_INIT_DATA \|\| \ (type) == MOD_INIT_RODATA) ``` Right, so it's a simple check for whether `type` matches `MOD_INIT_TEXT`, `MOD_INIT_DATA`, or `MOD_INIT_RODATA`. We know these are enum values, like 3, 4, and 5... but what's our comparison case? We are evaluating the case `((unsigned long)MOD_STANDALONE & SH_ENTSIZE_TYPE_MASK)`. This, apparently, is evaluating to `((-2) & 0xf) = 14`. Okay, so 14 is definitely not 3, 4, or 5. This means that `mod_mem_type_is_init(14)` will evaluate to false. So `is_core_symbol` is still returning true for percpu symbols if `CONFIG_KALLSYMS_ALL` is set, which is exactly how it behaved previously. I understand this part. But wait... what about codetag symbols? That's the next layer here. Codetag sections are also tagged with `SH_ENTSIZE_STANDALONE`. Codetag sections also have the `SHF_ALLOC` flag set. Are these codetag symbols core symbols? Yes, `is_core_symbol` is returning true for them, as it should (and as it has been if they are module or codetag symbols). But hang on, what about `module_get_offset_and_type`? This is something I should definitely review...
108/3	2026/09/15 07:52	tool	read-file	0m Args: { "File": "kernel/module/main.c", "FirstLine": 1655, "LineCount": 30 } Results: { "Contents": "1655:\t}\n1656:\t\n1657:\tlong module_get_offset_and_type(struct module mod, enum mod_mem_type type,\n1658:\t\t\t\t\tElf_Shdr sechdr, unsigned int section)\n1659:\t{\n1660:\t\tlong offset;\n1661:\t\tlong mask = ((unsigned long)(type) \u0026 SH_ENTSIZE_TYPE_MASK) \u003c\u003c SH_ENTSIZE_TYPE_SHIFT;\n1662:\t\n1663:\t\tmod-\u003emem[type].size += arch_mod_section_prepend(mod, section);\n1664:\t\toffset = ALIGN(mod-\u003emem[type].size, sechdr-\u003esh_addralign ?: 1);\n1665:\t\tmod-\u003emem[type].size = offset + sechdr-\u003esh_size;\n1666:\t\n1667:\t\tWARN_ON_ONCE(offset \u0026 mask);\n1668:\t\treturn offset \| mask;\n1669:\t}\n1670:\t\n1671:\tbool module_init_layout_section(const char sname)\n1672:\t{\n1673:\t#ifndef CONFIG_MODULE_UNLOAD\n1674:\t\tif (module_exit_section(sname))\n1675:\t\t\treturn true;\n1676:\t#endif\n1677:\t\treturn module_init_section(sname);\n1678:\t}\n1679:\t\n1680:\tstatic void __layout_sections(struct module mod, struct load_info info, bool is_init)\n1681:\t{\n1682:\t\tunsigned int m, i;\n1683:\t\n1684:\t\t/\n" }
109/3	2026/09/15 07:52	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 44508 output: 307 thoughts: 1996 Thoughts: Patch Analysis and KMSAN Justification Okay, let's break this down. My goal here is to determine if this patch series necessitates KMSAN testing. Based on my understanding, this patch series is refactoring how codetag sections are handled during module loading. Essentially, it's about allocating codetag memory upfront, allowing modules to gracefully handle codetag pool exhaustion, and making sure that errors are handled. The original logic had a problem where module loads could fail because codetag sections were allocated in `move_module`, and there was a fallback problem if `reserve_module_tags` failed. This patch moves the allocation earlier, improves error handling, and provides a fall-back. Here's my thought process as I've gone through the changes: First, let's consider the changes themselves. We've got: 1. Enum/macros for tagging standalone sections, no uninitialized reads or writes. 2. `kallsyms.c`: Removing a parameter; no uninitialized memory concerns. 3. `main.c`: The core of the changes. We're skipping sections during layout, allocating codetag sections BEFORE layout, updating section headers to indicate standalone sections. There's also `memcpy` and `memset` in `allocate_codetag_sections` to properly initialize buffers. Error paths are handled. The logic around percpu sections, and the changes were handled. 4. `sysfs.c`: Adding a visibility flag, using `kzalloc`. No obvious memory leaks, use of uninitialized memory. 5. `codetag.c`: Handles `-EOPNOTSUPP`, proper freeing of memory. 6. `alloc_tag.c`: Deferred proc entry removal, properly restores tags size and maple tree entries when `reserve_module_tags` fails, and returns `-EOPNOTSUPP` if profiling is disabled. Based on this review, it appears that all memory allocations are either initialized with `memset`/`memcpy` or allocated using `kzalloc`. The most likely issues would be related to memory management (deadlocks, use-after-free, double-free), out-of-bounds access, or error handling. Now, let's analyze the KMSAN requirement. The rule is clear: KMSAN is for detecting uninitialized memory risks that aren't caught by KASAN or standard detectors. Considering the patch changes, are there any potential uninitialized memory risks? No. There are no uninitialized variables read, no info-leaks, or conditional execution based on uninitialized data. The memory buffers used are initialized to 0 or initialized from the image. The potential issues are use-after-free bugs, deadlocks, out-of-bounds access, or error-handling issues, are already detected by KASAN/LOCKDEP/kmemleak. Here's my reasoning. The changes are primarily in module layout, codetag allocation, sysfs section attribute creation, per-cpu section handling, error unwinding, and workqueue deferral. Any bugs here would result in use-after-free, double-free, out-of-bounds access, memory leaks, or locking deadlocks during module loading/unloading. Standard detectors catch these issues. KMSAN would detect reads of uninitialized memory and uninitialized data copied to userspace. All buffers are initialized. Structures are allocated with `kzalloc`. There are no uninitialized struct fields, or uninitialized memory leaks. Therefore, `NeedsKMSAN = false`. We're not introducing or exposing any risks that KMSAN is specifically designed to detect.
110/3	2026/09/15 07:52	tool	set-results	0m Args: { "KMSANReasoning": "The patch series refactors module loading for standalone sections (.data..percpu and codetag sections like alloc_tag), handling fallback when contiguous codetag memory overflows, adjusting module section layout and relocation logic, deferring /proc/allocinfo removal via a workqueue to avoid deadlocks, and cleaning up error unwinding paths in vm_module_tags_populate().\n\n- KASAN \u0026 standard detector applicability: The changes touch module section memory allocation, life-cycle management, error unwinding, and sysfs/procfs registrations. Potential bugs in these areas include out-of-bounds accesses during section layout/relocation, use-after-free / double-free during codetag unload or error rollback, and deadlocks in shutdown paths. These risks are fully covered by KASAN, LOCKDEP, and kmemleak.\n- KMSAN applicability: KMSAN detects uninitialized memory reads and kernel-to-user info-leaks. In this patch series, newly allocated standalone sections are completely initialized via memcpy() or memset() depending on section type (SHT_NOBITS). Sysfs attribute structures are allocated using kzalloc_flex() and kzalloc_objs() which zero memory. No conditional branches rely on uninitialized data, and no uninitialized padding or buffer content is exposed to userspace.\n\nTherefore, running a dedicated KMSAN session is not warranted.", "NeedsKMSAN": false } Results: { "KMSANReasoning": "The patch series refactors module loading for standalone sections (.data..percpu and codetag sections like alloc_tag), handling fallback when contiguous codetag memory overflows, adjusting module section layout and relocation logic, deferring /proc/allocinfo removal via a workqueue to avoid deadlocks, and cleaning up error unwinding paths in vm_module_tags_populate().\n\n- KASAN \u0026 standard detector applicability: The changes touch module section memory allocation, life-cycle management, error unwinding, and sysfs/procfs registrations. Potential bugs in these areas include out-of-bounds accesses during section layout/relocation, use-after-free / double-free during codetag unload or error rollback, and deadlocks in shutdown paths. These risks are fully covered by KASAN, LOCKDEP, and kmemleak.\n- KMSAN applicability: KMSAN detects uninitialized memory reads and kernel-to-user info-leaks. In this patch series, newly allocated standalone sections are completely initialized via memcpy() or memset() depending on section type (SHT_NOBITS). Sysfs attribute structures are allocated using kzalloc_flex() and kzalloc_objs() which zero memory. No conditional branches rely on uninitialized data, and no uninitialized padding or buffer content is exposed to userspace.\n\nTherefore, running a dedicated KMSAN session is not warranted.", "NeedsKMSAN": false }

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