AI Trajectory

Trajectory: (Expand/Collapse All)
Seq	Timestamp	Type	Name	Duration
0/0	2026/09/07 08:43	flow	patch-triage	2m Args: null Results: { "EnableConfigs": [ "MODULES", "MEM_ALLOC_PROFILING", "KALLSYMS" ], "FocusSymbols": [ "allocate_codetag_sections", "reserve_module_tags", "release_module_tags", "layout_and_allocate", "move_module", "layout_symtab", "add_kallsyms" ], "KMSANReasoning": "The patch refactors module section layout and allocation to handle standalone sections (such as `.data..percpu` and codetag sections). Specifically:\n1. `.data..percpu` retains its `SHF_ALLOC` flag and is marked as `SH_ENTSIZE_STANDALONE`, allowing it to be properly exposed via `/sys/module/*/sections/\u003csection\u003e` pointing to the boot CPU instance.\n2. Codetag section allocation is moved earlier into a dedicated helper (`allocate_codetag_sections`), with proper fallback to regular section allocation if codetag memory is exhausted.\n3. Copied memory is explicitly initialized using `memcpy` or `memset` for NOBITS sections, and sysfs reading formats addresses safely into bounded buffers via `scnprintf`.\n4. No uninitialized variables, struct paddings, or buffers are read or copied to userspace.\n\nAny potential bugs from these changes (such as memory management errors, out-of-bounds access during ELF parsing, or error-path resource cleanup) are covered by KASAN and standard kernel debugging facilities. A dedicated KMSAN run is not needed.", "NeedsKMSAN": false, "Reasoning": "The patch refactors the kernel module layout mechanism for standalone sections (such as per-CPU sections and codetag sections) and updates memory allocation tag management on tag overflow/failure. These changes affect reachable module loading paths via init_module/finit_module syscalls and warrant fuzzing.", "WorthFuzzing": true }
1/1	2026/09/07 08:43	action	read-patch-diff	0m Args: null Results: { "PatchDiff": "commit 67f048212c297720c5e5109237d6b1162b55581e\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate: Mon Sep 7 08:43:17 2026 +0000\n\n syz-cluster: applied patch under review\n\ndiff --git a/Documentation/ABI/testing/sysfs-module b/Documentation/ABI/testing/sysfs-module\nindex d5b7d19bd3103..65e152c6fa58d 100644\n--- a/Documentation/ABI/testing/sysfs-module\n+++ b/Documentation/ABI/testing/sysfs-module\n@@ -57,6 +57,14 @@ Description:\tList of symbol namespaces imported by this module via\n \t\tThis file only exists for modules that import at least one\n \t\tnamespace.\n \n+What:\t\t/sys/module//sections/\u003csection\u003e\n+Date:\t\tJune 2005\n+KernelVersion:\t2.6.12\n+Contact:\tlinux-modules@vger.kernel.org\n+Description:\tThe memory address of the given loaded section of the\n+\t\tmodule. .data..percpu has one instance per CPU; the\n+\t\taddress reported is the instance of the boot CPU.\n+\n What:\t\t/sys/module//taint\n Date:\t\tJan 2012\n KernelVersion:\t3.3\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..5f36852659dfb 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;\n@@ -3531,6 +3540,11 @@ static int load_module(struct load_info info, const char __user uargs,\n \tif (err \u003c 0)\n \t\tgoto free_modinfo;\n \n+\t/* The percpu ELF section is a template; report the boot CPU instance. /\n+\tif (info-\u003eindex.pcpu)\n+\t\tinfo-\u003esechdrs[info-\u003eindex.pcpu].sh_addr =\n+\t\t\t(unsigned long)per_cpu_ptr(mod-\u003epercpu, get_boot_cpu_id());\n+\n \tflush_module_icache(mod);\n \n \t/ Now copy in args /\ndiff --git a/mm/alloc_tag.c b/mm/alloc_tag.c\nindex f30ef8dd24c70..8f13369b32ecd 100644\n--- a/mm/alloc_tag.c\n+++ b/mm/alloc_tag.c\n@@ -843,6 +843,52 @@ 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@@ -912,10 +958,12 @@ static void reserve_module_tags(struct module mod, unsigned long 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\treturn ERR_PTR(-EAGAIN);\n \t\t}\n \n \t\tgrow_res = vm_module_tags_populate();\n@@ -923,6 +971,7 @@ 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\treturn ERR_PTR(grow_res);\n \t\t}\n \t}\n@@ -930,52 +979,6 @@ 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" }
2/1	2026/09/07 08:43	agent	patch-evaluator	0m Model: core Args: null Results: { "EnableConfigs": [ "MODULES", "MEM_ALLOC_PROFILING", "KALLSYMS" ], "FocusSymbols": [ "allocate_codetag_sections", "reserve_module_tags", "release_module_tags", "layout_and_allocate", "move_module", "layout_symtab", "add_kallsyms" ], "Reasoning": "The patch refactors the kernel module layout mechanism for standalone sections (such as per-CPU sections and codetag sections) and updates memory allocation tag management on tag overflow/failure. These changes affect reachable module loading paths via init_module/finit_module syscalls and warrant fuzzing.", "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 67f048212c297720c5e5109237d6b1162b55581e Author: syz-cluster <triage@syzkaller.com> Date: Mon Sep 7 08:43:17 2026 +0000 syz-cluster: applied patch under review diff --git a/Documentation/ABI/testing/sysfs-module b/Documentation/ABI/testing/sysfs-module index d5b7d19bd3103..65e152c6fa58d 100644 --- a/Documentation/ABI/testing/sysfs-module +++ b/Documentation/ABI/testing/sysfs-module @@ -57,6 +57,14 @@ Description: List of symbol namespaces imported by this module via This file only exists for modules that import at least one namespace. +What: /sys/module//sections/<section> +Date: June 2005 +KernelVersion: 2.6.12 +Contact: linux-modules@vger.kernel.org +Description: The memory address of the given loaded section of the + module. .data..percpu has one instance per CPU; the + address reported is the instance of the boot CPU. + What: /sys/module//taint Date: Jan 2012 KernelVersion: 3.3 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..5f36852659dfb 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; @@ -3531,6 +3540,11 @@ static int load_module(struct load_info info, const char __user uargs, if (err < 0) goto free_modinfo; + /* The percpu ELF section is a template; report the boot CPU instance. / + if (info->index.pcpu) + info->sechdrs[info->index.pcpu].sh_addr = + (unsigned long)per_cpu_ptr(mod->percpu, get_boot_cpu_id()); + flush_module_icache(mod); / Now copy in args / diff --git a/mm/alloc_tag.c b/mm/alloc_tag.c index f30ef8dd24c70..8f13369b32ecd 100644 --- a/mm/alloc_tag.c +++ b/mm/alloc_tag.c @@ -843,6 +843,52 @@ 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) { @@ -912,10 +958,12 @@ static void reserve_module_tags(struct module mod, unsigned long 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); + return ERR_PTR(-EAGAIN); } grow_res = vm_module_tags_populate(); @@ -923,6 +971,7 @@ 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); return ERR_PTR(grow_res); } } @@ -930,52 +979,6 @@ 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 */
3/2	2026/09/07 08:43	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 8718 output: 21 thoughts: 608 Thoughts: Analyzing This Patch Series for Fuzzing Potential Okay, so the task is to determine if this patch series is interesting enough to warrant fuzzing with syzkaller. Let's dig in. I see changes across the module loading and allocation infrastructure, so this could be fruitful. I need to understand the scope and nature of the modifications to assess the risk surface it presents. First, the diff touches on: * Documentation, which is good, but doesn't immediately suggest a fuzzing target. * `include/linux/module.h` - defining `MOD_STANDALONE`, and that's interesting. It looks like we're dealing with a new module memory type. * `kernel/module/` and `mm/alloc_tag.c` - these are the juicy bits! The changes to `kallsyms.c`, `main.c`, and `alloc_tag.c` are what I need to focus on. Looks like a bunch of section layout changes. Specifically, `allocate_codetag_sections` is new, and that's a red flag. There are changes around how sections are allocated, moved, and tagged, which likely interacts with the module loading process. The added checks on allocation success/failure are relevant too. From the quick review, it seems like we're potentially dealing with memory allocation and management, possibly around per-CPU sections or codetags. The `SH_ENTSIZE_STANDALONE` constant, changes to `apply_relocations` and the handling of allocation errors (`-EAGAIN`) in `allocate_codetag_sections` and `reserve_module_tags` are immediately catching my attention. The `reserve_module_tags` changes in `alloc_tag.c` are intriguing, especially the error handling and conditions there. This is likely a key area for potential vulnerabilities. I need to see what configurations are involved, and I'll need to check the exact code and Kconfig files for the symbols. I'll fire up `grepper` or `read-file` to get a closer look at `mm/alloc_tag.c` and everything in `kernel/module/`. This should give me a better understanding of what modules are affected, and what the code's behavior really is.
4/2	2026/09/07 08:43	tool	grepper	0m Args: { "Expression": "MEM_ALLOC_PROFILING" } Results: { "Output": "Documentation/admin-guide/sysctl/vm.rst=22=Currently, these files are in /proc/sys/vm:\n--\nDocumentation/admin-guide/sysctl/vm.rst-43-- max_map_count\nDocumentation/admin-guide/sysctl/vm.rst:44:- mem_profiling (only if CONFIG_MEM_ALLOC_PROFILING=y)\nDocumentation/admin-guide/sysctl/vm.rst-45-- memory_failure_early_kill\n--\nDocumentation/admin-guide/sysctl/vm.rst=476=mem_profiling\n--\nDocumentation/admin-guide/sysctl/vm.rst-478-\nDocumentation/admin-guide/sysctl/vm.rst:479:Enable memory profiling (when CONFIG_MEM_ALLOC_PROFILING=y)\nDocumentation/admin-guide/sysctl/vm.rst-480-\n--\nDocumentation/admin-guide/sysctl/vm.rst=486=memory allocations.\nDocumentation/admin-guide/sysctl/vm.rst-487-\nDocumentation/admin-guide/sysctl/vm.rst:488:The default value depends on CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT.\nDocumentation/admin-guide/sysctl/vm.rst-489-\nDocumentation/admin-guide/sysctl/vm.rst:490:When CONFIG_MEM_ALLOC_PROFILING_DEBUG=y, this control is read-only to avoid\nDocumentation/admin-guide/sysctl/vm.rst-491-warnings produced by allocations made while profiling is disabled and freed\n--\nDocumentation/mm/allocation-profiling.rst=11=kconfig options:\nDocumentation/mm/allocation-profiling.rst:12:- CONFIG_MEM_ALLOC_PROFILING\nDocumentation/mm/allocation-profiling.rst-13-\nDocumentation/mm/allocation-profiling.rst:14:- CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT\nDocumentation/mm/allocation-profiling.rst-15-\nDocumentation/mm/allocation-profiling.rst:16:- CONFIG_MEM_ALLOC_PROFILING_DEBUG\nDocumentation/mm/allocation-profiling.rst-17- adds warnings for allocations that weren't accounted because of a\n--\nDocumentation/mm/allocation-profiling.rst=20=Boot parameter:\n--\nDocumentation/mm/allocation-profiling.rst-24- cannot be enabled at runtime (sysctl becomes read-only).\nDocumentation/mm/allocation-profiling.rst:25: When CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT=y, default value is \"1\".\nDocumentation/mm/allocation-profiling.rst:26: When CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT=n, default value is \"never\".\nDocumentation/mm/allocation-profiling.rst-27- \"compressed\" optional parameter will try to store page tag references in a\n--\nDocumentation/mm/allocation-profiling.rst=33=sysctl:\n--\nDocumentation/mm/allocation-profiling.rst-39-\nDocumentation/mm/allocation-profiling.rst:40: The default value depends on CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT.\nDocumentation/mm/allocation-profiling.rst-41-\nDocumentation/mm/allocation-profiling.rst:42: When CONFIG_MEM_ALLOC_PROFILING_DEBUG=y, this control is read-only to avoid\nDocumentation/mm/allocation-profiling.rst-43- warnings produced by allocations made while profiling is disabled and freed\n--\ninclude/asm-generic/codetag.lds.h-4-\ninclude/asm-generic/codetag.lds.h:5:#ifdef CONFIG_MEM_ALLOC_PROFILING\ninclude/asm-generic/codetag.lds.h:6:#define IF_MEM_ALLOC_PROFILING(...) __VA_ARGS__\ninclude/asm-generic/codetag.lds.h-7-#else\ninclude/asm-generic/codetag.lds.h:8:#define IF_MEM_ALLOC_PROFILING(...)\ninclude/asm-generic/codetag.lds.h-9-#endif\n--\ninclude/asm-generic/codetag.lds.h-17-#define CODETAG_SECTIONS()\t\t\\\ninclude/asm-generic/codetag.lds.h:18:\tIF_MEM_ALLOC_PROFILING(SECTION_WITH_BOUNDARIES(alloc_tags))\ninclude/asm-generic/codetag.lds.h-19-\n--\ninclude/asm-generic/codetag.lds.h-30-#define MOD_SEPARATE_CODETAG_SECTIONS()\t\t\\\ninclude/asm-generic/codetag.lds.h:31:\tIF_MEM_ALLOC_PROFILING(MOD_SEPARATE_CODETAG_SECTION(alloc_tags))\ninclude/asm-generic/codetag.lds.h-32-\n--\ninclude/linux/alloc_tag.h=38=struct alloc_tag_module_section {\n--\ninclude/linux/alloc_tag.h-47-\ninclude/linux/alloc_tag.h:48:#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG\ninclude/linux/alloc_tag.h-49-\n--\ninclude/linux/alloc_tag.h=57=static inline void set_codetag_empty(union codetag_ref ref)\n--\ninclude/linux/alloc_tag.h-62-\ninclude/linux/alloc_tag.h:63:#else / CONFIG_MEM_ALLOC_PROFILING_DEBUG /\ninclude/linux/alloc_tag.h-64-\n--\ninclude/linux/alloc_tag.h=67=static inline void set_codetag_empty(union codetag_ref ref)\n--\ninclude/linux/alloc_tag.h-72-\ninclude/linux/alloc_tag.h:73:#endif /* CONFIG_MEM_ALLOC_PROFILING_DEBUG /\ninclude/linux/alloc_tag.h-74-\ninclude/linux/alloc_tag.h:75:#ifdef CONFIG_MEM_ALLOC_PROFILING\ninclude/linux/alloc_tag.h-76-\n--\ninclude/linux/alloc_tag.h=97=DECLARE_PER_CPU(struct alloc_tag_counters, _shared_alloc_tag);\n--\ninclude/linux/alloc_tag.h-127-\ninclude/linux/alloc_tag.h:128:DECLARE_STATIC_KEY_MAYBE(CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT,\ninclude/linux/alloc_tag.h-129-\t\t\tmem_alloc_profiling_key);\n--\ninclude/linux/alloc_tag.h=131=static inline bool mem_alloc_profiling_enabled(void)\ninclude/linux/alloc_tag.h-132-{\ninclude/linux/alloc_tag.h:133:\treturn static_branch_maybe(CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT,\ninclude/linux/alloc_tag.h-134-\t\t\t\t \u0026mem_alloc_profiling_key);\n--\ninclude/linux/alloc_tag.h=139=static inline struct alloc_tag_counters alloc_tag_read(struct alloc_tag tag)\n--\ninclude/linux/alloc_tag.h-153-\ninclude/linux/alloc_tag.h:154:#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG\ninclude/linux/alloc_tag.h-155-static inline void alloc_tag_add_check(union codetag_ref ref, struct alloc_tag tag)\n--\ninclude/linux/alloc_tag.h=233=static inline bool alloc_tag_is_inaccurate(struct alloc_tag tag)\n--\ninclude/linux/alloc_tag.h-239-\ninclude/linux/alloc_tag.h:240:#else / CONFIG_MEM_ALLOC_PROFILING /\ninclude/linux/alloc_tag.h-241-\n--\ninclude/linux/alloc_tag.h=249=static inline bool alloc_tag_is_inaccurate(struct alloc_tag tag) { return false; }\n--\ninclude/linux/alloc_tag.h-251-\ninclude/linux/alloc_tag.h:252:#endif /* CONFIG_MEM_ALLOC_PROFILING /\ninclude/linux/alloc_tag.h-253-\n--\ninclude/linux/pgalloc_tag.h-9-\ninclude/linux/pgalloc_tag.h:10:#ifdef CONFIG_MEM_ALLOC_PROFILING\ninclude/linux/pgalloc_tag.h-11-\n--\ninclude/linux/pgalloc_tag.h=202=void __init alloc_tag_sec_init(void);\ninclude/linux/pgalloc_tag.h-203-\ninclude/linux/pgalloc_tag.h:204:#else / CONFIG_MEM_ALLOC_PROFILING /\ninclude/linux/pgalloc_tag.h-205-\n--\ninclude/linux/pgalloc_tag.h=210=static inline struct alloc_tag pgalloc_tag_get(struct page page) { return NULL; }\ninclude/linux/pgalloc_tag.h-211-\ninclude/linux/pgalloc_tag.h:212:#endif / CONFIG_MEM_ALLOC_PROFILING /\ninclude/linux/pgalloc_tag.h-213-\n--\ninclude/linux/rhashtable-types.h=86=struct rhashtable {\n--\ninclude/linux/rhashtable-types.h-96-\tatomic_t\t\t\tnelems;\ninclude/linux/rhashtable-types.h:97:#ifdef CONFIG_MEM_ALLOC_PROFILING\ninclude/linux/rhashtable-types.h-98-\tstruct alloc_tag\t\talloc_tag;\n--\ninclude/linux/sched.h=835=struct task_struct {\n--\ninclude/linux/sched.h-859-\ninclude/linux/sched.h:860:#ifdef CONFIG_MEM_ALLOC_PROFILING\ninclude/linux/sched.h-861-\tstruct alloc_tag\t\talloc_tag;\n--\ninclude/linux/sched.h=2356=extern void sched_set_stop_task(int cpu, struct task_struct stop);\ninclude/linux/sched.h-2357-\ninclude/linux/sched.h:2358:#ifdef CONFIG_MEM_ALLOC_PROFILING\ninclude/linux/sched.h-2359-static __always_inline struct alloc_tag alloc_tag_save(struct alloc_tag tag)\n--\ninclude/linux/sched.h=2365=static __always_inline void alloc_tag_restore(struct alloc_tag tag, struct alloc_tag old)\ninclude/linux/sched.h-2366-{\ninclude/linux/sched.h:2367:#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG\ninclude/linux/sched.h-2368-\tWARN(current-\u003ealloc_tag != tag, \"current-\u003ealloc_tag was changed:\\n\");\n--\nmm/Kconfig.debug=311=config PER_VMA_LOCK_STATS\n--\nmm/Kconfig.debug-322-\nmm/Kconfig.debug:323:config MEM_ALLOC_PROFILING\nmm/Kconfig.debug-324-\tbool \"Enable memory allocation profiling\"\n--\nmm/Kconfig.debug-335-\nmm/Kconfig.debug:336:config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT\nmm/Kconfig.debug-337-\tbool \"Enable memory allocation profiling by default\"\nmm/Kconfig.debug-338-\tdefault y\nmm/Kconfig.debug:339:\tdepends on MEM_ALLOC_PROFILING\nmm/Kconfig.debug-340-\nmm/Kconfig.debug:341:config MEM_ALLOC_PROFILING_DEBUG\nmm/Kconfig.debug-342-\tbool \"Memory allocation profiler debugging\"\nmm/Kconfig.debug-343-\tdefault n\nmm/Kconfig.debug:344:\tdepends on MEM_ALLOC_PROFILING\nmm/Kconfig.debug:345:\tselect MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT\nmm/Kconfig.debug-346-\thelp\n--\nmm/Makefile=150=obj-$(CONFIG_LAZY_MMU_MODE_KUNIT_TEST) += tests/lazy_mmu_mode_kunit.o\nmm/Makefile:151:obj-$(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=1129=static __init bool need_page_alloc_tagging(void)\n--\nmm/alloc_tag.c-1136-\nmm/alloc_tag.c:1137:#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG\nmm/alloc_tag.c-1138-/\n--\nmm/alloc_tag.c=1215=static void __init clear_early_alloc_pfn_tag_refs(void)\n--\nmm/alloc_tag.c-1268-}\nmm/alloc_tag.c:1269:#else / !CONFIG_MEM_ALLOC_PROFILING_DEBUG /\nmm/alloc_tag.c-1270-static inline void __init clear_early_alloc_pfn_tag_refs(void) {}\nmm/alloc_tag.c:1271:#endif / CONFIG_MEM_ALLOC_PROFILING_DEBUG /\nmm/alloc_tag.c-1272-\n--\nmm/alloc_tag.c=1290=static int proc_mem_profiling_handler(const struct ctl_table table, int write,\n--\nmm/alloc_tag.c-1301-\nmm/alloc_tag.c:1302:#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG\nmm/alloc_tag.c-1303-\t\t/* User can't toggle profiling while debugging /\n--\nmm/page_alloc.c=1202=static void clear_highpages_kasan_tagged(struct page page, int numpages)\n--\nmm/page_alloc.c-1216-\nmm/page_alloc.c:1217:#ifdef CONFIG_MEM_ALLOC_PROFILING\nmm/page_alloc.c-1218-\n--\nmm/page_alloc.c=1283=static inline void pgalloc_tag_sub_pages(struct alloc_tag tag, unsigned int nr)\n--\nmm/page_alloc.c-1288-\nmm/page_alloc.c:1289:#else / CONFIG_MEM_ALLOC_PROFILING /\nmm/page_alloc.c-1290-\n--\nmm/page_alloc.c=1294=static inline void pgalloc_tag_sub_pages(struct alloc_tag tag, unsigned int nr) {}\nmm/page_alloc.c-1295-\nmm/page_alloc.c:1296:#endif /* CONFIG_MEM_ALLOC_PROFILING /\nmm/page_alloc.c-1297-\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=1688=static void pcpu_memcg_free_hook(struct pcpu_chunk chunk, int off, size_t size)\n--\nmm/percpu.c-1692-\nmm/percpu.c:1693:#ifdef CONFIG_MEM_ALLOC_PROFILING\nmm/percpu.c-1694-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	2026/09/07 08:43	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 15357 output: 22 thoughts: 693 Thoughts: Analyzing a Kernel Module Patch Series Okay, let's dive into this patch series. My initial thought is to really understand what's being modified, so I'll start by dissecting the diffs. Looks like the core of the changes is centered around how codetag sections are allocated and handled during module loading. Specifically, they're moving the codetag section allocation from `move_module` to earlier in the process, during `layout_and_allocate`. I need to understand why this shift is happening and what benefits it brings. From the code, it seems the patch series addresses scenarios where allocation fails, offering a fallback to treating the codetag section as a regular section. When allocated separately, it also seems to be explicitly handling memory copies and skipping these sections during `move_module`. There's also some interesting logic involving percpu sections, setting `sh_entsize` to `SH_ENTSIZE_STANDALONE` rather than clearing the `SHF_ALLOC` flag. This seems like a significant deviation from existing behavior and needs close scrutiny. The changes to relocation application and `kallsyms` suggest this alters how those components interact with percpu sections now, and the removal of the specific exception in `apply_relocations` is something that warrants a closer look at the implications. The inclusion of `release_module_tags` and `reserve_module_tags` in `alloc_tag.c` is also important in understanding resource handling in these changes. Next, I need to understand the practical impact of these changes. Is this core kernel logic? Based on the files being touched (module loader, memory management, kallsyms, and allocation tags), it seems to be. And the `init_module`/`finit_module` syscalls are definitely accessible even in standard virtualized environments like QEMU or GCE. This means it's definitely something that's reachable and fuzzable. I'll need to remember that in the evaluation. Now let's check the relevant configs involved. We're obviously looking at `CONFIG_MODULES`, which is a core feature, and potentially `CONFIG_MEM_ALLOC_PROFILING` and `CONFIG_KALLSYMS`. I should keep an eye out for other potentially relevant configs too, but that gives me a good start. I need to keep these configurations in mind as they likely influence the behavior being modified here.
6/2	2026/09/07 08:43	tool	grepper	0m Args: { "Expression": "codetag_needs_module_section" } Results: { "Output": "include/linux/codetag.h=88=codetag_register_type(const struct codetag_type_desc desc);\n--\ninclude/linux/codetag.h-91-\ninclude/linux/codetag.h:92:bool codetag_needs_module_section(struct module mod, const char name,\ninclude/linux/codetag.h-93-\t\t\t\t unsigned long size);\n--\ninclude/linux/codetag.h=104=static inline bool\ninclude/linux/codetag.h:105:codetag_needs_module_section(struct module mod, const char name,\ninclude/linux/codetag.h-106-\t\t\t unsigned long size) { return false; }\n--\nkernel/module/main.c=2919=static int allocate_codetag_sections(struct load_info info)\n--\nkernel/module/main.c-2925-\nkernel/module/main.c:2926:\t\tif (!codetag_needs_module_section(info-\u003emod, sname, shdr-\u003esh_size))\nkernel/module/main.c-2927-\t\t\tcontinue;\n--\nlib/codetag.c=194=static int codetag_module_init(struct codetag_type cttype, struct module mod)\n--\nlib/codetag.c-254-/* Some codetag types need a separate module section /\nlib/codetag.c:255:bool codetag_needs_module_section(struct module mod, const char *name,\nlib/codetag.c-256-\t\t\t\t unsigned long size)\n" }
7/2	2026/09/07 08:43	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 16982 output: 18 thoughts: 35 Thoughts: Okay, here's my take on those thoughts, framed as an expert in the field: Digging into Codetag Configuration Dependencies Alright, before I dive too deep into this, I need to get a clear picture of how `codetag` is configured and where its dependencies lie within the build system. My immediate instinct is to check a couple of key files. I'll need to look closely at `lib/codetag.c` – it's the obvious place to start, as the C source is where the core logic resides, and that often reveals any config options it directly uses. Then, I'll need to examine the Kconfig files. The `lib/Kconfig.debug` or just `lib/Kconfig` files are where all the configuration options for that library are likely defined. Knowing which config options are relevant is critical for understanding the build process and how `codetag` interacts with the broader system, and those files will list the dependencies. By cross-referencing these files, I should have a good handle on how the code is configured.
8/2	2026/09/07 08:43	tool	grepper	0m Error: no matches Args: { "Expression": "config CODETAG" } Results: { "error": "no matches" }
9/2	2026/09/07 08:43	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 17274 output: 18 thoughts: 14 Thoughts: Here's my take on those thoughts, tailored for an expert audience: Makefile Grepping for Code Tags Okay, so I'm thinking, "Time to dig into this Makefile and see what's what." My immediate impulse is to use `grep`. Specifically, I want to find all instances of something like `obj-something.codetag`. I'm assuming that the `obj-*` prefix indicates object files, and the `codetag` suffix likely relates to some sort of code tagging or instrumentation process within the build. Maybe it's for static analysis, debugging, profiling, or something along those lines. Using grep will allow me to quickly identify which object files are associated with this tagging mechanism. From there, I can investigate the surrounding context within the Makefile to gain a better understanding of how the tagging is implemented and utilized.
10/2	2026/09/07 08:43	tool	grepper	0m Args: { "Expression": "codetag\\.o" } Results: { "Output": "lib/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" }
11/2	2026/09/07 08:43	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 17562 output: 19 thoughts: 17 Thoughts: Okay, here's my summarized thought process, presented as if I were thinking it: Investigating Configuration Dependencies Alright, I need to figure out what's enabling `CODE_TAGGING` in this system. My first instinct is to dive into the configuration files. Given the nature of this, the most efficient approach is to leverage a tool like `grep`. Specifically, I'll use `grep` to search within the configuration for the string `CODE_TAGGING`. This will quickly reveal where and how this particular setting is being defined or influenced. This should give me a good handle on its dependencies or enabling conditions.
12/2	2026/09/07 08:43	tool	grepper	0m Args: { "Expression": "config CODE_TAGGING" } 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" }
13/2	2026/09/07 08:43	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 17808 output: 19 thoughts: 12 Thoughts: Okay, here's my attempt at summarizing that thought process, keeping in mind I'm speaking to a fellow expert: Investigating the `CODE_TAGGING` Selection Alright, let's dive in. My initial thought process here is pretty straightforward. I'm focusing in on what's selecting or triggering the `CODE_TAGGING` functionality. This isn't a nebulous request; it's a pinpointed query. I'm not just idly pondering, but actively trying to understand the control flow, the conditions, or the data dependencies that lead to this specific module or feature being activated. I need to understand the causal chain. Is it a direct call, a configuration setting, a data input, a specific user action? Understanding this selection mechanism is crucial for debugging, optimizing, or even just grasping the larger system's behavior. I need to understand the "why" of the selection. This sets the stage for further investigation.
14/2	2026/09/07 08:43	tool	grepper	0m Args: { "Expression": "select CODE_TAGGING" } Results: { "Output": "mm/Kconfig.debug=323=config MEM_ALLOC_PROFILING\n--\nmm/Kconfig.debug-327-\tdepends on PROC_FS\nmm/Kconfig.debug:328:\tselect CODE_TAGGING\nmm/Kconfig.debug-329-\tselect PAGE_EXTENSION\n" }
15/2	2026/09/07 08:43	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 18126 output: 34 thoughts: 44 Thoughts: Okay, here's my interpretation of that thought process, assuming I'm deep in the weeds of kernel configuration: Investigating the Memory Allocation Profiling Configuration Alright, so `CONFIG_MEM_ALLOC_PROFILING` automatically pulls in `CODE_TAGGING`. That makes sense, I suppose; tagging allocations is probably fundamental to profiling them effectively. But I need to double-check my assumptions and get the full picture. My first instinct is to drill down into the Kconfig for that area. Let's see... I should go straight to `mm/Kconfig.debug`. That's where I'd expect to find the dependencies and any further details on `CONFIG_MEM_ALLOC_PROFILING`. I want to understand why this dependency is in place and what other configurations it might affect. Time to dig in and confirm the relationship!
16/2	2026/09/07 08:43	tool	grepper	0m Args: { "Expression": "config MEM_ALLOC_PROFILING", "PathPrefix": "mm/Kconfig.debug" } Results: { "Output": "mm/Kconfig.debug=311=config PER_VMA_LOCK_STATS\n--\nmm/Kconfig.debug-322-\nmm/Kconfig.debug:323:config MEM_ALLOC_PROFILING\nmm/Kconfig.debug-324-\tbool \"Enable memory allocation profiling\"\n--\nmm/Kconfig.debug-335-\nmm/Kconfig.debug:336:config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT\nmm/Kconfig.debug-337-\tbool \"Enable memory allocation profiling by default\"\n--\nmm/Kconfig.debug-340-\nmm/Kconfig.debug:341:config MEM_ALLOC_PROFILING_DEBUG\nmm/Kconfig.debug-342-\tbool \"Memory allocation profiler debugging\"\n" }
17/2	2026/09/07 08:43	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 18592 output: 34 thoughts: 23 Thoughts: Here's a summary of my thought process, as if I were the one reading `mm/Kconfig.debug`: Diving into Kconfig.debug - Lines 320-350 Okay, time to get specific. I'm focusing on lines 320 through 350 within `mm/Kconfig.debug`. I know this section is dedicated to debug options for the memory management subsystem, so I'm expecting to find some configuration knobs that can affect how the kernel behaves during development and debugging, likely related to tracing, extra checks, or perhaps specific instrumentation. I'll need to pay close attention to the dependencies – what other options need to be enabled for these to even show up? Are they nested under a specific `DEBUG` flag, or do they rely on a particular memory management model or feature? Knowing the context of the surrounding code will be important, too, so I'll keep an eye on what immediately precedes and follows this block. I'm hoping to identify some useful options that can help me with the current issue I'm investigating... or perhaps some new techniques to add to my toolbox. Let's see what gems are hidden here.
18/2	2026/09/07 08:44	tool	read-file	0m Args: { "File": "mm/Kconfig.debug", "FirstLine": 320, "LineCount": 35 } Results: { "Contents": " 320:\t\n 321:\t\t If in doubt, say N.\n 322:\t\n 323:\tconfig MEM_ALLOC_PROFILING\n 324:\t\tbool \"Enable memory allocation profiling\"\n 325:\t\tdefault n\n 326:\t\tdepends on MMU\n 327:\t\tdepends on PROC_FS\n 328:\t\tselect CODE_TAGGING\n 329:\t\tselect PAGE_EXTENSION\n 330:\t\tselect SLAB_OBJ_EXT\n 331:\t\thelp\n 332:\t\t Track allocation source code and record total allocation size\n 333:\t\t initiated at that code location. The mechanism can be used to track\n 334:\t\t memory leaks with a low performance and memory impact.\n 335:\t\n 336:\tconfig MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT\n 337:\t\tbool \"Enable memory allocation profiling by default\"\n 338:\t\tdefault y\n 339:\t\tdepends on MEM_ALLOC_PROFILING\n 340:\t\n 341:\tconfig MEM_ALLOC_PROFILING_DEBUG\n 342:\t\tbool \"Memory allocation profiler debugging\"\n 343:\t\tdefault n\n 344:\t\tdepends on MEM_ALLOC_PROFILING\n 345:\t\tselect MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT\n 346:\t\thelp\n 347:\t\t Adds warnings with helpful error messages for memory allocation\n 348:\t\t profiling.\n" }
19/2	2026/09/07 08:44	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 19293 output: 28 thoughts: 128 Thoughts: Kernel Module Configuration Review Okay, time to make sure this kernel build is set up correctly. First, I need to verify the `MODULES` configuration. It's essential; it's the foundation for all module loading, so that's a given. Next, I want to confirm `CONFIG_MEM_ALLOC_PROFILING` is enabled and set up as expected. I'm also thinking about `CONFIG_KALLSYMS`. That's important for symbol tables. Let me take a look at `kernel/module/kallsyms.c`. I need to ensure the core functions related to symbol management are compiled if `CONFIG_KALLSYMS` is enabled. Specifically, I need to check how `is_core_symbol`, `layout_symtab`, and `add_kallsyms` are handled. They should be protected by the `CONFIG_KALLSYMS` macro. Then, I should confirm the module build rules defined in `kernel/module/Makefile`. This will provide the full picture.
20/2	2026/09/07 08:44	tool	grepper	0m Args: { "Expression": "kallsyms", "PathPrefix": "kernel/module/" } Results: { "Output": "kernel/module/Makefile=18=obj-$(CONFIG_DEBUG_KMEMLEAK) += debug_kmemleak.o\nkernel/module/Makefile:19:obj-$(CONFIG_KALLSYMS) += kallsyms.o\nkernel/module/Makefile-20-obj-$(CONFIG_PROC_FS) += procfs.o\n--\nkernel/module/internal.h=70=struct load_info {\n--\nkernel/module/internal.h-80-#ifdef CONFIG_KALLSYMS\nkernel/module/internal.h:81:\tunsigned long mod_kallsyms_init_off;\nkernel/module/internal.h-82-#endif\n--\nkernel/module/internal.h=365=void layout_symtab(struct module mod, struct load_info info);\nkernel/module/internal.h:366:void add_kallsyms(struct module mod, const struct load_info info);\nkernel/module/internal.h-367-\n--\nkernel/module/internal.h=374=static inline void layout_symtab(struct module mod, struct load_info info) { }\nkernel/module/internal.h:375:static inline void add_kallsyms(struct module mod, const struct load_info info) { }\nkernel/module/internal.h-376-#endif /* CONFIG_KALLSYMS /\n--\nkernel/module/kallsyms.c-2-/\nkernel/module/kallsyms.c:3: * Module kallsyms support\nkernel/module/kallsyms.c-4- \n--\nkernel/module/kallsyms.c-9-#include \u003clinux/module_symbol.h\u003e\nkernel/module/kallsyms.c:10:#include \u003clinux/kallsyms.h\u003e\nkernel/module/kallsyms.c-11-#include \u003clinux/buildid.h\u003e\n--\nkernel/module/kallsyms.c=108=void layout_symtab(struct module mod, struct load_info info)\n--\nkernel/module/kallsyms.c-138-\tmod_mem_data-\u003esize += strtab_size;\nkernel/module/kallsyms.c:139:\t/ Note add_kallsyms() computes strtab_size as core_typeoffs - stroffs /\nkernel/module/kallsyms.c-140-\tinfo-\u003ecore_typeoffs = mod_mem_data-\u003esize;\n--\nkernel/module/kallsyms.c-148-\nkernel/module/kallsyms.c:149:\t/ We'll tack temporary mod_kallsyms on the end. /\nkernel/module/kallsyms.c-150-\tmod_mem_init_data-\u003esize = ALIGN(mod_mem_init_data-\u003esize,\nkernel/module/kallsyms.c:151:\t\t\t\t\t__alignof__(struct mod_kallsyms));\nkernel/module/kallsyms.c:152:\tinfo-\u003emod_kallsyms_init_off = mod_mem_init_data-\u003esize;\nkernel/module/kallsyms.c-153-\nkernel/module/kallsyms.c:154:\tmod_mem_init_data-\u003esize += sizeof(struct mod_kallsyms);\nkernel/module/kallsyms.c-155-\tinfo-\u003einit_typeoffs = mod_mem_init_data-\u003esize;\n--\nkernel/module/kallsyms.c-163- /\nkernel/module/kallsyms.c:164:void add_kallsyms(struct module mod, const struct load_info info)\nkernel/module/kallsyms.c-165-{\n--\nkernel/module/kallsyms.c-173-\tvoid init_data_base = mod-\u003emem[MOD_INIT_DATA].base;\nkernel/module/kallsyms.c:174:\tstruct mod_kallsyms kallsyms;\nkernel/module/kallsyms.c-175-\nkernel/module/kallsyms.c:176:\tkallsyms = init_data_base + info-\u003emod_kallsyms_init_off;\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;\nkernel/module/kallsyms.c-183-\nkernel/module/kallsyms.c-184-\t/\nkernel/module/kallsyms.c:185:\t Now populate the cut down core kallsyms for after init\nkernel/module/kallsyms.c-186-\t * and set types up while we still have access to sections.\nkernel/module/kallsyms.c-187-\t /\nkernel/module/kallsyms.c:188:\tmod-\u003ecore_kallsyms.symtab = dst = data_base + info-\u003esymoffs;\nkernel/module/kallsyms.c:189:\tmod-\u003ecore_kallsyms.strtab = s = data_base + info-\u003estroffs;\nkernel/module/kallsyms.c:190:\tmod-\u003ecore_kallsyms.typetab = data_base + info-\u003ecore_typeoffs;\nkernel/module/kallsyms.c-191-\tstrtab_size = info-\u003ecore_typeoffs - info-\u003estroffs;\nkernel/module/kallsyms.c:192:\tsrc = kallsyms-\u003esymtab;\nkernel/module/kallsyms.c:193:\tfor (ndst = i = 0; i \u003c kallsyms-\u003enum_symtab; i++) {\nkernel/module/kallsyms.c:194:\t\tkallsyms-\u003etypetab[i] = elf_type(src + i, info);\nkernel/module/kallsyms.c-195-\t\tif (i == 0 \|\| is_livepatch_module(mod) \|\|\n--\nkernel/module/kallsyms.c-198-\nkernel/module/kallsyms.c:199:\t\t\tmod-\u003ecore_kallsyms.typetab[ndst] =\nkernel/module/kallsyms.c:200:\t\t\t\tkallsyms-\u003etypetab[i];\nkernel/module/kallsyms.c-201-\t\t\tdst[ndst] = src[i];\nkernel/module/kallsyms.c:202:\t\t\tdst[ndst++].st_name = s - mod-\u003ecore_kallsyms.strtab;\nkernel/module/kallsyms.c:203:\t\t\tret = strscpy(s, \u0026kallsyms-\u003estrtab[src[i].st_name],\nkernel/module/kallsyms.c-204-\t\t\t\t strtab_size);\n--\nkernel/module/kallsyms.c-212-\t/ Set up to point into init section. /\nkernel/module/kallsyms.c:213:\trcu_assign_pointer(mod-\u003ekallsyms, kallsyms);\nkernel/module/kallsyms.c:214:\tmod-\u003ecore_kallsyms.num_symtab = ndst;\nkernel/module/kallsyms.c-215-}\n--\nkernel/module/kallsyms.c=232=void init_build_id(struct module mod, const struct load_info info)\n--\nkernel/module/kallsyms.c-236-\nkernel/module/kallsyms.c:237:static const char kallsyms_symbol_name(struct mod_kallsyms kallsyms, unsigned int symnum)\nkernel/module/kallsyms.c-238-{\nkernel/module/kallsyms.c:239:\treturn kallsyms-\u003estrtab + kallsyms-\u003esymtab[symnum].st_name;\nkernel/module/kallsyms.c-240-}\n--\nkernel/module/kallsyms.c-245- /\nkernel/module/kallsyms.c:246:static const char find_kallsyms_symbol(struct module mod,\nkernel/module/kallsyms.c-247-\t\t\t\t\tunsigned long addr,\n--\nkernel/module/kallsyms.c-252-\tunsigned long nextval, bestval;\nkernel/module/kallsyms.c:253:\tstruct mod_kallsyms kallsyms = rcu_dereference(mod-\u003ekallsyms);\nkernel/module/kallsyms.c-254-\tstruct module_memory mod_mem = NULL;\n--\nkernel/module/kallsyms.c-277-\t /\nkernel/module/kallsyms.c:278:\tfor (i = 1; i \u003c kallsyms-\u003enum_symtab; i++) {\nkernel/module/kallsyms.c:279:\t\tconst Elf_Sym sym = \u0026kallsyms-\u003esymtab[i];\nkernel/module/kallsyms.c:280:\t\tunsigned long thisval = kallsyms_symbol_value(sym);\nkernel/module/kallsyms.c-281-\n--\nkernel/module/kallsyms.c-288-\t\t /\nkernel/module/kallsyms.c:289:\t\tif (kallsyms_symbol_name(kallsyms, i) == '\\0' \|\|\nkernel/module/kallsyms.c:290:\t\t is_mapping_symbol(kallsyms_symbol_name(kallsyms, i)))\nkernel/module/kallsyms.c-291-\t\t\tcontinue;\n--\nkernel/module/kallsyms.c-308-\nkernel/module/kallsyms.c:309:\treturn kallsyms_symbol_name(kallsyms, best);\nkernel/module/kallsyms.c-310-}\n--\nkernel/module/kallsyms.c=312=void * __weak dereference_module_function_descriptor(struct module mod,\n--\nkernel/module/kallsyms.c-318-/\nkernel/module/kallsyms.c:319: * For kallsyms to ask for address resolution. NULL means not found. Careful\nkernel/module/kallsyms.c-320- * not to lock to avoid deadlock on oopses, RCU is enough.\n--\nkernel/module/kallsyms.c=322=int module_address_lookup(unsigned long addr,\n--\nkernel/module/kallsyms.c-340-\nkernel/module/kallsyms.c:341:\t\tsym = find_kallsyms_symbol(mod, addr, size, offset);\nkernel/module/kallsyms.c-342-\n--\nkernel/module/kallsyms.c=349=int lookup_module_symbol_name(unsigned long addr, char symname)\n--\nkernel/module/kallsyms.c-359-\nkernel/module/kallsyms.c:360:\t\t\tsym = find_kallsyms_symbol(mod, addr, NULL, NULL);\nkernel/module/kallsyms.c-361-\t\t\tif (!sym)\n--\nkernel/module/kallsyms.c=372=int module_get_kallsym(unsigned int symnum, unsigned long value, char type,\n--\nkernel/module/kallsyms.c-378-\tlist_for_each_entry_rcu(mod, \u0026modules, list) {\nkernel/module/kallsyms.c:379:\t\tstruct mod_kallsyms kallsyms;\nkernel/module/kallsyms.c-380-\n--\nkernel/module/kallsyms.c-382-\t\t\tcontinue;\nkernel/module/kallsyms.c:383:\t\tkallsyms = rcu_dereference(mod-\u003ekallsyms);\nkernel/module/kallsyms.c:384:\t\tif (symnum \u003c kallsyms-\u003enum_symtab) {\nkernel/module/kallsyms.c:385:\t\t\tconst Elf_Sym sym = \u0026kallsyms-\u003esymtab[symnum];\nkernel/module/kallsyms.c-386-\nkernel/module/kallsyms.c:387:\t\t\tvalue = kallsyms_symbol_value(sym);\nkernel/module/kallsyms.c:388:\t\t\ttype = kallsyms-\u003etypetab[symnum];\nkernel/module/kallsyms.c:389:\t\t\tstrscpy(name, kallsyms_symbol_name(kallsyms, symnum), KSYM_NAME_LEN);\nkernel/module/kallsyms.c-390-\t\t\tstrscpy(module_name, mod-\u003ename, MODULE_NAME_LEN);\n--\nkernel/module/kallsyms.c-393-\t\t}\nkernel/module/kallsyms.c:394:\t\tsymnum -= kallsyms-\u003enum_symtab;\nkernel/module/kallsyms.c-395-\t}\n--\nkernel/module/kallsyms.c-399-/ Given a module and name of symbol, find and return the symbol's value /\nkernel/module/kallsyms.c:400:static unsigned long __find_kallsyms_symbol_value(struct module mod, const char name)\nkernel/module/kallsyms.c-401-{\nkernel/module/kallsyms.c-402-\tunsigned int i;\nkernel/module/kallsyms.c:403:\tstruct mod_kallsyms kallsyms = rcu_dereference(mod-\u003ekallsyms);\nkernel/module/kallsyms.c-404-\nkernel/module/kallsyms.c:405:\tfor (i = 0; i \u003c kallsyms-\u003enum_symtab; i++) {\nkernel/module/kallsyms.c:406:\t\tconst Elf_Sym sym = \u0026kallsyms-\u003esymtab[i];\nkernel/module/kallsyms.c-407-\nkernel/module/kallsyms.c:408:\t\tif (strcmp(name, kallsyms_symbol_name(kallsyms, i)) == 0 \u0026\u0026\nkernel/module/kallsyms.c-409-\t\t sym-\u003est_shndx != SHN_UNDEF)\nkernel/module/kallsyms.c:410:\t\t\treturn kallsyms_symbol_value(sym);\nkernel/module/kallsyms.c-411-\t}\n--\nkernel/module/kallsyms.c-414-\nkernel/module/kallsyms.c:415:static unsigned long __module_kallsyms_lookup_name(const char name)\nkernel/module/kallsyms.c-416-{\n--\nkernel/module/kallsyms.c-423-\t\tif (mod)\nkernel/module/kallsyms.c:424:\t\t\treturn __find_kallsyms_symbol_value(mod, colon + 1);\nkernel/module/kallsyms.c-425-\t\treturn 0;\n--\nkernel/module/kallsyms.c-432-\t\t\tcontinue;\nkernel/module/kallsyms.c:433:\t\tret = __find_kallsyms_symbol_value(mod, name);\nkernel/module/kallsyms.c-434-\t\tif (ret)\n--\nkernel/module/kallsyms.c-440-/* Look for this name: can be of form module:name. /\nkernel/module/kallsyms.c:441:unsigned long module_kallsyms_lookup_name(const char name)\nkernel/module/kallsyms.c-442-{\n--\nkernel/module/kallsyms.c-444-\tguard(rcu)();\nkernel/module/kallsyms.c:445:\treturn __module_kallsyms_lookup_name(name);\nkernel/module/kallsyms.c-446-}\nkernel/module/kallsyms.c-447-\nkernel/module/kallsyms.c:448:unsigned long find_kallsyms_symbol_value(struct module mod, const char name)\nkernel/module/kallsyms.c-449-{\nkernel/module/kallsyms.c-450-\tguard(rcu)();\nkernel/module/kallsyms.c:451:\treturn __find_kallsyms_symbol_value(mod, name);\nkernel/module/kallsyms.c-452-}\nkernel/module/kallsyms.c-453-\nkernel/module/kallsyms.c:454:int module_kallsyms_on_each_symbol(const char modname,\nkernel/module/kallsyms.c-455-\t\t\t\t int (fn)(void , const char , unsigned long),\n--\nkernel/module/kallsyms.c-463-\tlist_for_each_entry(mod, \u0026modules, list) {\nkernel/module/kallsyms.c:464:\t\tstruct mod_kallsyms kallsyms;\nkernel/module/kallsyms.c-465-\n--\nkernel/module/kallsyms.c-471-\nkernel/module/kallsyms.c:472:\t\tkallsyms = rcu_dereference_check(mod-\u003ekallsyms,\nkernel/module/kallsyms.c-473-\t\t\t\t\t\t lockdep_is_held(\u0026module_mutex));\nkernel/module/kallsyms.c-474-\nkernel/module/kallsyms.c:475:\t\tfor (i = 0; i \u003c kallsyms-\u003enum_symtab; i++) {\nkernel/module/kallsyms.c:476:\t\t\tconst Elf_Sym sym = \u0026kallsyms-\u003esymtab[i];\nkernel/module/kallsyms.c-477-\n--\nkernel/module/kallsyms.c-480-\nkernel/module/kallsyms.c:481:\t\t\tret = fn(data, kallsyms_symbol_name(kallsyms, i),\nkernel/module/kallsyms.c:482:\t\t\t\t kallsyms_symbol_value(sym));\nkernel/module/kallsyms.c-483-\t\t\tif (ret != 0)\n--\nkernel/module/livepatch.c=18=int copy_module_elf(struct module mod, struct load_info info)\n--\nkernel/module/livepatch.c-52-\t/\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\nkernel/module/livepatch.c-56-\t * init memory is freed at the end of do_init_module().\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-16-#include \u003clinux/init.h\u003e\nkernel/module/main.c:17:#include \u003clinux/kallsyms.h\u003e\nkernel/module/main.c-18-#include \u003clinux/buildid.h\u003e\n--\nkernel/module/main.c=1417=static void free_module(struct module mod)\n--\nkernel/module/main.c-1446-\tmutex_lock(\u0026module_mutex);\nkernel/module/main.c:1447:\t/* Unlink carefully: kallsyms could be walking list. /\nkernel/module/main.c-1448-\tlist_del_rcu(\u0026mod-\u003elist);\n--\nkernel/module/main.c=3027=static int post_relocation(struct module mod, const struct load_info info)\n--\nkernel/module/main.c-3035-\nkernel/module/main.c:3036:\t/ Setup kallsyms-specific fields. /\nkernel/module/main.c:3037:\tadd_kallsyms(mod, info);\nkernel/module/main.c-3038-\n--\nkernel/module/main.c=3044=static void do_mod_ctors(struct module mod)\n--\nkernel/module/main.c-3053-\nkernel/module/main.c:3054:/* For freeing module_init on success, in case kallsyms traversing /\nkernel/module/main.c-3055-struct mod_initfree {\n--\nkernel/module/main.c=3097=static noinline int do_init_module(struct module mod)\n--\nkernel/module/main.c-3167-#ifdef CONFIG_KALLSYMS\nkernel/module/main.c:3168:\t/* Switch to core kallsyms now init is done: kallsyms may be walking! /\nkernel/module/main.c:3169:\trcu_assign_pointer(mod-\u003ekallsyms, \u0026mod-\u003ecore_kallsyms);\nkernel/module/main.c-3170-#endif\n--\nkernel/module/main.c-3189-\t/\nkernel/module/main.c:3190:\t * We want to free module_init, but be aware that kallsyms may be\nkernel/module/main.c-3191-\t * walking this within an RCU read section. In all the failure paths, we\n--\nkernel/module/main.c=3327=static int complete_formation(struct module mod, struct load_info info)\n--\nkernel/module/main.c-3353-\t * Mark state as coming so strong_try_module_get() ignores us,\nkernel/module/main.c:3354:\t * but kallsyms etc. can see us.\nkernel/module/main.c-3355-\t /\n--\nkernel/module/main.c=3442=static int load_module(struct load_info info, const char __user uargs,\n--\nkernel/module/main.c-3639-\tmutex_lock(\u0026module_mutex);\nkernel/module/main.c:3640:\t/ Unlink carefully: kallsyms could be walking list. /\nkernel/module/main.c-3641-\tlist_del_rcu(\u0026mod-\u003elist);\n--\nkernel/module/procfs.c-8-#include \u003clinux/module.h\u003e\nkernel/module/procfs.c:9:#include \u003clinux/kallsyms.h\u003e\nkernel/module/procfs.c-10-#include \u003clinux/mutex.h\u003e\n--\nkernel/module/procfs.c=112=static const struct seq_operations modules_op = {\n--\nkernel/module/procfs.c-123- \nkernel/module/procfs.c:124: * We use the same logic as for /proc/kallsyms.\nkernel/module/procfs.c-125- /\nkernel/module/procfs.c=126=static int modules_open(struct inode inode, struct file file)\n--\nkernel/module/procfs.c-132-\nkernel/module/procfs.c:133:\t\tm-\u003eprivate = kallsyms_show_value(file-\u003ef_cred) ? NULL : (void )8ul;\nkernel/module/procfs.c-134-\t}\n--\nkernel/module/sysfs.c-12-#include \u003clinux/slab.h\u003e\nkernel/module/sysfs.c:13:#include \u003clinux/kallsyms.h\u003e\nkernel/module/sysfs.c-14-#include \u003clinux/mutex.h\u003e\n--\nkernel/module/sysfs.c=28=static ssize_t module_sect_read(struct file file, struct kobject kobj,\n--\nkernel/module/sysfs.c-46-\twrote = scnprintf(bounce, sizeof(bounce), \"0x%px\\n\",\nkernel/module/sysfs.c:47:\t\t\t kallsyms_show_value(file-\u003ef_cred)\nkernel/module/sysfs.c-48-\t\t\t\t? battr-\u003eprivate : NULL);\n" }
21/2	2026/09/07 08:44	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 26101 output: 19 thoughts: 869 Thoughts: Analysis of Modified Kernel Module Loading Logic for Fuzzing Alright, let's break this down. My goal here is to identify the most effective targets for fuzzing, given these changes to kernel module loading and related memory management. I'm focusing on functions that have been modified and are likely to expose new code paths or vulnerabilities. First, I need to establish if these changes are "WorthFuzzing". It's clear that the modifications touch core module loading, specifically: the codetag section allocation, the layout and allocation of memory for modules, relocation application, kallsyms logic, and memory allocation profiling tag management. These functions are critical and directly invoked during module loading via `init_module` and `finit_module` syscalls, which means this code is definitely reachable. The fallback handling introduced in `allocate_codetag_sections` (error handling, memory copying) and tag limit checks / handling in `reserve_module_tags` particularly catch my eye as likely areas for fuzzing. Given this, `WorthFuzzing = true` is the right call. Now, let's identify the specific functions that warrant closer inspection. I've narrowed it down to: `allocate_codetag_sections`, `layout_and_allocate`, `reserve_module_tags`, `release_module_tags`, `layout_symtab`, `add_kallsyms`, and `move_module`. I need to ensure these aren't ubiquitous functions; if they're called all over the kernel, they're less likely to be helpful for specific fuzzing targeted at these changes. After review, it's clear these are primarily used during module lifecycle events which is key. Finally, I need to make sure the fuzzing environment is correctly set up. I've identified the necessary configuration options: `MODULES`, `MEM_ALLOC_PROFILING`, and `KALLSYMS`. `MODULES` is a given; we need to build modules. `MEM_ALLOC_PROFILING` is crucial, enabling the use of allocation tags and codetag sections. I need to make sure `MEM_ALLOC_PROFILING`'s dependencies, `MMU` and `PROC_FS`, are enabled, which they usually are in standard AMD64 configs. Lastly, `KALLSYMS` enables the kallsyms functionality, which is essential to have during debugging. It's a top-level config, and I'll confirm it's correct from `init/Kconfig`.
22/2	2026/09/07 08:44	tool	grepper	0m Args: { "Expression": "config KALLSYMS" } Results: { "Output": "init/Kconfig=2079=config CACHESTAT_SYSCALL\n--\ninit/Kconfig-2088-\ninit/Kconfig:2089:config KALLSYMS\ninit/Kconfig-2090-\tbool \"Load all symbols for debugging/ksymoops\" if EXPERT\n--\ninit/Kconfig-2096-\ninit/Kconfig:2097:config KALLSYMS_SELFTEST\ninit/Kconfig-2098-\tbool \"Test the basic functions and performance of kallsyms\"\n--\ninit/Kconfig-2109-\ninit/Kconfig:2110:config KALLSYMS_ALL\ninit/Kconfig-2111-\tbool \"Include all symbols in kallsyms\"\n--\nkernel/ksyms_common.c-3- * ksyms_common.c: A split of kernel/kallsyms.c\nkernel/ksyms_common.c:4: * Contains a few generic function definations independent of config KALLSYMS.\nkernel/ksyms_common.c-5- */\n" }
23/2	2026/09/07 08:44	llm	patch-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 27798 output: 165 thoughts: 183 Thoughts: My Fuzzing Strategy: A Quick Review Okay, before I dive in, I need to make sure I'm following my own rules. Let's do a quick mental checklist: First, the core triage philosophy: We're targeting module loading, specifically anything reachable through `finit_module` and `init_module` syscalls. Any significant refactoring or logic changes in the core module layout or alloc tag management is definitely something worth focusing on for fuzzing. Next, I've got my FocusSymbols in mind. I want to keep this precise, so I'm looking at specific functions that aren't overly common: `allocate_codetag_sections`, `reserve_module_tags`, `release_module_tags`, `layout_and_allocate`, `move_module`, `layout_symtab`, and `add_kallsyms`. These are the key areas for deeper investigation. Then I have my EnableConfigs selected: I need to ensure `MODULES` is enabled, naturally. Beyond that, I need to enable `MEM_ALLOC_PROFILING` and `KALLSYMS`. These configs will give me the visibility I need. And finally, my Reasoning is clear, concise. Now that I'm confident I've got everything in order, let's go ahead and call `set-results`. I'm ready to move forward.
24/2	2026/09/07 08:44	tool	set-results	0m Args: { "EnableConfigs": [ "MODULES", "MEM_ALLOC_PROFILING", "KALLSYMS" ], "FocusSymbols": [ "allocate_codetag_sections", "reserve_module_tags", "release_module_tags", "layout_and_allocate", "move_module", "layout_symtab", "add_kallsyms" ], "Reasoning": "The patch refactors the kernel module layout mechanism for standalone sections (such as per-CPU sections and codetag sections) and updates memory allocation tag management on tag overflow/failure. These changes affect reachable module loading paths via init_module/finit_module syscalls and warrant fuzzing.", "WorthFuzzing": true } Results: { "EnableConfigs": [ "MODULES", "MEM_ALLOC_PROFILING", "KALLSYMS" ], "FocusSymbols": [ "allocate_codetag_sections", "reserve_module_tags", "release_module_tags", "layout_and_allocate", "move_module", "layout_symtab", "add_kallsyms" ], "Reasoning": "The patch refactors the kernel module layout mechanism for standalone sections (such as per-CPU sections and codetag sections) and updates memory allocation tag management on tag overflow/failure. These changes affect reachable module loading paths via init_module/finit_module syscalls and warrant fuzzing.", "WorthFuzzing": true }
25/1	2026/09/07 08:44	action	If	1m Args: { "WorthFuzzing": true } Results: null
26/2	2026/09/07 08:44	agent	kmsan-evaluator	1m Model: core Args: null Results: { "KMSANReasoning": "The patch refactors module section layout and allocation to handle standalone sections (such as `.data..percpu` and codetag sections). Specifically:\n1. `.data..percpu` retains its `SHF_ALLOC` flag and is marked as `SH_ENTSIZE_STANDALONE`, allowing it to be properly exposed via `/sys/module//sections/\u003csection\u003e` pointing to the boot CPU instance.\n2. Codetag section allocation is moved earlier into a dedicated helper (`allocate_codetag_sections`), with proper fallback to regular section allocation if codetag memory is exhausted.\n3. Copied memory is explicitly initialized using `memcpy` or `memset` for NOBITS sections, and sysfs reading formats addresses safely into bounded buffers via `scnprintf`.\n4. No uninitialized variables, struct paddings, or buffers are read or copied to userspace.\n\nAny potential bugs from these changes (such as memory management errors, out-of-bounds access during ELF parsing, or error-path resource cleanup) are covered by KASAN and standard kernel debugging facilities. A dedicated KMSAN run is not needed.", "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 67f048212c297720c5e5109237d6b1162b55581e Author: syz-cluster <triage@syzkaller.com> Date: Mon Sep 7 08:43:17 2026 +0000 syz-cluster: applied patch under review diff --git a/Documentation/ABI/testing/sysfs-module b/Documentation/ABI/testing/sysfs-module index d5b7d19bd3103..65e152c6fa58d 100644 --- a/Documentation/ABI/testing/sysfs-module +++ b/Documentation/ABI/testing/sysfs-module @@ -57,6 +57,14 @@ Description: List of symbol namespaces imported by this module via This file only exists for modules that import at least one namespace. +What: /sys/module//sections/<section> +Date: June 2005 +KernelVersion: 2.6.12 +Contact: linux-modules@vger.kernel.org +Description: The memory address of the given loaded section of the + module. .data..percpu has one instance per CPU; the + address reported is the instance of the boot CPU. + What: /sys/module//taint Date: Jan 2012 KernelVersion: 3.3 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..5f36852659dfb 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; @@ -3531,6 +3540,11 @@ static int load_module(struct load_info info, const char __user uargs, if (err < 0) goto free_modinfo; + /* The percpu ELF section is a template; report the boot CPU instance. / + if (info->index.pcpu) + info->sechdrs[info->index.pcpu].sh_addr = + (unsigned long)per_cpu_ptr(mod->percpu, get_boot_cpu_id()); + flush_module_icache(mod); / Now copy in args / diff --git a/mm/alloc_tag.c b/mm/alloc_tag.c index f30ef8dd24c70..8f13369b32ecd 100644 --- a/mm/alloc_tag.c +++ b/mm/alloc_tag.c @@ -843,6 +843,52 @@ 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) { @@ -912,10 +958,12 @@ static void reserve_module_tags(struct module mod, unsigned long 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); + return ERR_PTR(-EAGAIN); } grow_res = vm_module_tags_populate(); @@ -923,6 +971,7 @@ 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); return ERR_PTR(grow_res); } } @@ -930,52 +979,6 @@ 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 */
27/3	2026/09/07 08:44	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 7930 output: 22 thoughts: 996 Thoughts: KMSAN Evaluation of Patch Series Okay, let's break this down. My task is to determine whether this patch series necessitates a dedicated KMSAN session. The changes are spread across several files, so we need to trace the implications. The core of the modifications seems to revolve around handling "codetag" sections within modules, particularly related to standalone sections. We are adding `MOD_STANDALONE` to `enum mod_mem_type`, which suggests a new type of memory region. The `SH_ENTSIZE_STANDALONE` definition and the changes to `move_module`, `layout_and_allocate`, and the new `allocate_codetag_sections` function are the key areas of interest. The use of a separate tag allocation pool, and the potential for EAGAIN errors in allocation, implies a resource management challenge that could indirectly expose memory vulnerabilities. Specifically, the code is trying to handle situations where tag pool allocation overflows, and gracefully falling back to regular section allocation. This is a point of concern. If we are falling back to normal allocation in some cases, the fallback path needs to be inspected. Changes in `apply_relocations`, `layout_sections`, and `layout_symtab` hint at potentially modifying the memory layout of loaded modules. Removing the PCPU check in `apply_relocations` could mean we're changing how relocations are applied, impacting what data gets written to where. The modifications to `is_core_symbol` are less critical, as they seem to primarily simplify an existing check. The major concern I have is how codetag sections are allocated, initialized, and moved. Specifically, the introduction of a new allocation path. We need to be careful to make sure that the contents are either properly copied or zeroed. We also need to be careful to ensure that the code correctly handles memory allocation errors and potential uninitialized memory reads. I’m now going to use `grepper` (or `read-file` if needed) to dive deeper into those code paths, scrutinizing the data flow within `allocate_codetag_sections`, `layout_and_allocate`, and `move_module`, focusing on potential uninitialized memory risks. I'll pay close attention to the `memcpy` and `memset` operations to ensure that they are correctly handling the allocated memory. I’ll keep a sharp lookout for missing initialization steps or situations where the fallback logic might leave memory in an inconsistent state. The `mm/alloc_tag.c` changes are also crucial; the behavior in cases of tag pool exhaustion or memory allocation failure needs to be very carefully inspected for memory safety.
28/3	2026/09/07 08:44	tool	grepper	0m Args: { "Expression": "codetag_alloc_module_section" } Results: { "Output": "include/linux/codetag.h=92=bool codetag_needs_module_section(struct module mod, const char name,\ninclude/linux/codetag.h-93-\t\t\t\t unsigned long size);\ninclude/linux/codetag.h:94:void codetag_alloc_module_section(struct module mod, const char name,\ninclude/linux/codetag.h-95-\t\t\t\t unsigned long size, unsigned int prepend,\n--\ninclude/linux/codetag.h=107=static inline void \ninclude/linux/codetag.h:108:codetag_alloc_module_section(struct module mod, const char name,\ninclude/linux/codetag.h-109-\t\t\t unsigned long size, unsigned int prepend,\n--\nkernel/module/main.c=2919=static int allocate_codetag_sections(struct load_info info)\n--\nkernel/module/main.c-2928-\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);\n--\nlib/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" }
29/3	2026/09/07 08:44	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 9926 output: 37 thoughts: 36 Thoughts: Here's my thought process, as it relates to the kernel module and symbol resolution: Diving into `kallsyms.c` to Investigate Symbol Core-ness Okay, so I need to check how `is_core_symbol` is implemented. I'll need to head straight into `kernel/module/kallsyms.c`. That's where all the magic surrounding the kernel symbol table and, more specifically, the identification of "core" symbols, is handled. I need to understand the logic in `is_core_symbol` to accurately interpret its behavior. Let's get that code open and start digging.
30/3	2026/09/07 08:44	tool	read-file	0m Args: { "File": "kernel/module/kallsyms.c", "FirstLine": 70, "LineCount": 60 } 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 120:\t\t\t\t\t\t\t\t symsect, info-\u003eindex.sym);\n 121:\t\tpr_debug(\"\\t%s\\n\", info-\u003esecstrings + symsect-\u003esh_name);\n 122:\t\n 123:\t\tsrc = (void )info-\u003ehdr + symsect-\u003esh_offset;\n 124:\t\tnsrc = symsect-\u003esh_size / sizeof(src);\n 125:\t\n 126:\t\t/ Compute total space required for the core symbols' strtab. */\n 127:\t\tfor (ndst = i = 0; i \u003c nsrc; i++) {\n 128:\t\t\tif (i == 0 \|\| is_livepatch_module(mod) \|\|\n 129:\t\t\t is_core_symbol(src + i, info-\u003esechdrs, info-\u003ehdr-\u003ee_shnum)) {\n" }
31/3	2026/09/07 08:44	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 11164 output: 23 thoughts: 267 Thoughts: My Analysis of the `is_core_symbol` Function Okay, let's break this down. I'm looking at `is_core_symbol` and trying to understand why a specific conditional was present in the past. It looks like the original code included this: ```c #ifdef CONFIG_KALLSYMS_ALL if (src->st_shndx == pcpundx) return true; #endif ``` The reason for this check is that, previously, `info->sechdrs[info->index.pcpu].sh_flags &= ~(unsigned long)SHF_ALLOC;` was stripping the `SHF_ALLOC` flag from the per-CPU section. This is key. If we remove `SHF_ALLOC` from a per-CPU section, the logical negation `!(sec->sh_flags & SHF_ALLOC)` evaluates to true. Without the above check for percpu sections, this would incorrectly cause `is_core_symbol` to return `false` for those symbols. The explicit check was critical to handle percpu symbols correctly in this specific scenario. However, the patch I'm examining changes things. It now keeps `SHF_ALLOC` on the per-CPU section and marks `sh_entsize = SH_ENTSIZE_STANDALONE`. This is a significant shift in behavior. Because `SHF_ALLOC` is now present on the `.data..percpu` section, `!(sec->sh_flags & SHF_ALLOC)` will evaluate to false. This leads to the question of what happens now when we hit `mod_mem_type_is_init(type)`. What is the `type` being passed here for `SH_ENTSIZE_STANDALONE`? That's the critical question! I need to see what `mod_mem_type_is_init` does with this `type` value. Time to check its definition...
32/3	2026/09/07 08:44	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" }
33/3	2026/09/07 08:44	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 12156 output: 35 thoughts: 23 Thoughts: Here's my summary, as if I were thinking these thoughts: Diving into the Kernel Module Definitions Okay, time to get a handle on the module loading process again. Let's see... I need to refresh my memory on how this all fits together at the core. Right, so I'm thinking the best place to start is with the fundamental definitions. Let's head over to the `include/linux/module.h` file, specifically lines 320 through 345. That should give me a solid overview of the key structures and macros involved in module management. Hopefully, it will remind me of what I am looking for! I'm expecting to find the central data structures that describe a module and how they're used.
34/3	2026/09/07 08:44	tool	read-file	0m Args: { "File": "include/linux/module.h", "FirstLine": 320, "LineCount": 30 } Results: { "Contents": " 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 345:\t\n 346:\t#define mod_mem_type_is_core_data(type)\t\\\n 347:\t\t(mod_mem_type_is_core(type) \u0026\u0026\t\\\n 348:\t\t mod_mem_type_is_data(type))\n 349:\t\n" }
35/3	2026/09/07 08:44	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 12847 output: 29 thoughts: 287 Thoughts: My Analysis of Standalone Module Memory Allocation Okay, so I'm looking at how this code handles the initialization of module memory, specifically when dealing with standalone modules. The `mod_mem_type_is_init(type)` function is my starting point – it determines whether a memory type (`type`) requires explicit initialization, checking against `MOD_INIT_TEXT`, `MOD_INIT_DATA`, and `MOD_INIT_RODATA`. The key takeaway is that for `MOD_STANDALONE`, this function returns false. This is crucial because it means that core symbols within those standalone sections, like `percpu` and `codetags`, are treated differently – `is_core_symbol` considers them true. Now, let's dive into `allocate_codetag_sections`. It's clear that it's handling the actual memory allocation and population. Here's where it gets interesting: the code is using the section header (`shdr`) to decide how to handle the data. The check `shdr->sh_type != SHT_NOBITS` is the crux of it. If the section is not a "no bits" section (e.g., contains initialized data), the code copies the data from the location indicated by `shdr->sh_addr` into the newly allocated memory, using `memcpy`. Conversely, if it is a "no bits" section (like BSS segments), it uses `memset` to zero out the allocated memory. Then, after this process, it updates the `shdr` with the new destination address `dest` and the entry size. This is how the data is loaded into the new memory and the section header is updated to reflect this new memory layout. I need to compare this with how `move_module` used to handle this before, to understand the evolution of the allocation logic better. I'll need to go back and check the old code for that, but the basic process is clear here.
36/3	2026/09/07 08:44	tool	grepper	0m Args: { "Expression": "SHT_NOBITS", "PathPrefix": "kernel/module/" } Results: { "Output": "kernel/module/kallsyms.c=38=static char elf_type(const Elf_Sym sym, const struct load_info info)\n--\nkernel/module/kallsyms.c-56-\tif (sechdrs[sym-\u003est_shndx].sh_flags \u0026 SHF_ALLOC \u0026\u0026\nkernel/module/kallsyms.c:57:\t sechdrs[sym-\u003est_shndx].sh_type != SHT_NOBITS) {\nkernel/module/kallsyms.c-58-\t\tif (!(sechdrs[sym-\u003est_shndx].sh_flags \u0026 SHF_WRITE))\n--\nkernel/module/kallsyms.c-64-\t}\nkernel/module/kallsyms.c:65:\tif (sechdrs[sym-\u003est_shndx].sh_type == SHT_NOBITS) {\nkernel/module/kallsyms.c-66-\t\tif (sechdrs[sym-\u003est_shndx].sh_flags \u0026 ARCH_SHF_SMALL)\n--\nkernel/module/main.c=1922=static int elf_validity_cache_sechdrs(struct load_info info)\n--\nkernel/module/main.c-1968-\t\tcase SHT_NULL:\nkernel/module/main.c:1969:\t\tcase SHT_NOBITS:\nkernel/module/main.c-1970-\t\t\t/ No contents, offset/size don't mean anything /\n--\nkernel/module/main.c=2115=static int elf_validity_cache_index_mod(struct load_info info)\n--\nkernel/module/main.c-2128-\nkernel/module/main.c:2129:\tif (shdr-\u003esh_type == SHT_NOBITS) {\nkernel/module/main.c-2130-\t\tpr_err(\"module %s: .gnu.linkonce.this_module section must have a size set\\n\",\n--\nkernel/module/main.c=2780=static int move_module(struct module mod, struct load_info info)\n--\nkernel/module/main.c-2810-\nkernel/module/main.c:2811:\t\tif (shdr-\u003esh_type != SHT_NOBITS) {\nkernel/module/main.c-2812-\t\t\t/\n--\nkernel/module/main.c=2919=static int allocate_codetag_sections(struct load_info info)\n--\nkernel/module/main.c-2942-\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);\n" }
37/3	2026/09/07 08:44	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 14300 output: 36 thoughts: 19 Thoughts: Here's a summary of my thought process, as if I were considering the code around `move_module` in `kernel/module/main.c`: Deep Dive into Module Relocation Okay, so we're looking at `move_module` in `kernel/module/main.c`. My immediate thought is, "Ah, module relocation." That's a critical area, especially when we're talking about hot-plugging, unloading, and reloading modules dynamically. I need to refresh my understanding of how the kernel handles this. Specifically, I'm concerned about how `move_module` interacts with the symbol table, relocation entries, and section data. I'm thinking about the potential pitfalls here. Are we dealing with potential race conditions when modifying module memory? Are there any subtle issues with symbol resolution after the move – like dangling pointers or stale entries? Have we considered the implications for modules that interact closely with the kernel's internal data structures? I need to quickly recall the details of how the linker does this. We should have a very close look at the module sections `.text`, `.rodata`, `.data`, `.bss`, etc., and how they're handled. How does `move_module` deal with dependencies and circular references among modules, and does it do it correctly? Let's quickly check the surrounding code for any hints about memory barriers or locking mechanisms that they've employed in this section. I want to make sure the data integrity is sound during the move operation. Is `move_module` designed to prevent concurrent access while relocating? Also, it's vital to ensure that any potential modifications to the kernel's page table are handled carefully. We're potentially playing with the system's memory map here.
38/3	2026/09/07 08:44	tool	read-file	0m Args: { "File": "kernel/module/main.c", "FirstLine": 2805, "LineCount": 40 } Results: { "Contents": "2805:\t\t\t \|\| shdr-\u003esh_entsize == SH_ENTSIZE_STANDALONE)\n2806:\t\t\t\tcontinue;\n2807:\t\n2808:\t\t\tdest = mod-\u003emem[shdr-\u003esh_entsize \u003e\u003e SH_ENTSIZE_TYPE_SHIFT].base +\n2809:\t\t\t (shdr-\u003esh_entsize \u0026 SH_ENTSIZE_OFFSET_MASK);\n2810:\t\n2811:\t\t\tif (shdr-\u003esh_type != SHT_NOBITS) {\n2812:\t\t\t\t/\n2813:\t\t\t\t Our ELF checker already validated this, but let's\n2814:\t\t\t\t * be pedantic and make the goal clearer. We actually\n2815:\t\t\t\t * end up copying over all modifications made to the\n2816:\t\t\t\t * userspace copy of the entire struct module.\n2817:\t\t\t\t /\n2818:\t\t\t\tif (i == info-\u003eindex.mod \u0026\u0026\n2819:\t\t\t\t (WARN_ON_ONCE(shdr-\u003esh_size != sizeof(struct module)))) {\n2820:\t\t\t\t\tret = -ENOEXEC;\n2821:\t\t\t\t\tgoto out_err;\n2822:\t\t\t\t}\n2823:\t\t\t\tmemcpy(dest, (void )shdr-\u003esh_addr, shdr-\u003esh_size);\n2824:\t\t\t}\n2825:\t\t\t/\n2826:\t\t\t Update the userspace copy's ELF section address to point to\n2827:\t\t\t * our newly allocated memory as a pure convenience so that\n2828:\t\t\t * users of info can keep taking advantage and using the newly\n2829:\t\t\t * minted official memory area.\n2830:\t\t\t */\n2831:\t\t\tshdr-\u003esh_addr = (unsigned long)dest;\n2832:\t\t\tpr_debug(\"\\t0x%lx 0x%.8lx %s\\n\", (long)shdr-\u003esh_addr,\n2833:\t\t\t\t (long)shdr-\u003esh_size, info-\u003esecstrings + shdr-\u003esh_name);\n2834:\t\t}\n2835:\t\n2836:\t\treturn 0;\n2837:\tout_err:\n2838:\t\tmodule_memory_restore_rox(mod);\n2839:\t\twhile (t--)\n2840:\t\t\tmodule_memory_free(mod, t);\n2841:\t\n2842:\t\treturn ret;\n2843:\t}\n2844:\t\n" }
39/3	2026/09/07 08:44	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 15355 output: 35 thoughts: 91 Thoughts: Analyzing `alloc_tag.c` Module Tag Allocation Changes Okay, let's dive into these changes in `alloc_tag.c`. First thing's first, I see they've moved the `release_module_tags` function definition earlier in the file. That might be for readability, or perhaps it's related to some new dependencies. And the more interesting thing is that they added calls to `release_module_tags` in the error paths within `reserve_module_tags`, along with a `return ERR_PTR(-EAGAIN)` on tag exhaustion. This is pretty standard for memory management, cleaning up on failure is key. I want to understand the impact of that change though, so let's get a look at `mm/alloc_tag.c` and focus on the surrounding code of `reserve_module_tags`. I'm curious to see how the tag reservation logic itself has been modified and if there are any subtle side effects of the `EAGAIN` return.
40/3	2026/09/07 08:44	tool	read-file	0m Args: { "File": "mm/alloc_tag.c", "FirstLine": 945, "LineCount": 45 } Results: { "Contents": " 945:\t\t} else {\n 946:\t\t\tmas.last = offset + size - 1;\n 947:\t\t\tmas_store(\u0026mas, mod);\n 948:\t\t\tif (mas_is_err(\u0026mas))\n 949:\t\t\t\tret = ERR_PTR(xa_err(mas.node));\n 950:\t\t}\n 951:\tunlock:\n 952:\t\tmas_unlock(\u0026mas);\n 953:\t\n 954:\t\tif (IS_ERR(ret))\n 955:\t\t\treturn ret;\n 956:\t\n 957:\t\tif (module_tags.size \u003c offset + size) {\n 958:\t\t\tint grow_res;\n 959:\t\n 960:\t\t\tmodule_tags.size = offset + size;\n 961:\t\t\tif (!tags_addressable()) {\n 962:\t\t\t\tshutdown_mem_profiling(true);\n 963:\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 964:\t\t\t\t\t mod-\u003ename, NR_UNUSED_PAGEFLAG_BITS);\n 965:\t\t\t\trelease_module_tags(mod, false);\n 966:\t\t\t\treturn ERR_PTR(-EAGAIN);\n 967:\t\t\t}\n 968:\t\n 969:\t\t\tgrow_res = vm_module_tags_populate();\n 970:\t\t\tif (grow_res) {\n 971:\t\t\t\tshutdown_mem_profiling(true);\n 972:\t\t\t\tpr_err(\"Failed to allocate memory for allocation tags in the module %s. Memory allocation profiling is disabled!\\n\",\n 973:\t\t\t\t mod-\u003ename);\n 974:\t\t\t\trelease_module_tags(mod, false);\n 975:\t\t\t\treturn ERR_PTR(grow_res);\n 976:\t\t\t}\n 977:\t\t}\n 978:\t\n 979:\t\treturn (struct alloc_tag )(module_tags.start_addr + offset);\n 980:\t}\n 981:\t\n 982:\tstatic int load_module(struct module mod, struct codetag start, struct codetag stop)\n 983:\t{\n 984:\t\t/* Allocate module alloc_tag percpu counters /\n 985:\t\tstruct alloc_tag start_tag;\n 986:\t\tstruct alloc_tag stop_tag;\n 987:\t\tstruct alloc_tag tag;\n 988:\t\n 989:\t\t/* Profiling disabled: load the module without its tags. */\n" }
41/3	2026/09/07 08:44	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 16368 output: 31 thoughts: 235 Thoughts: Examining the Module Section Address Reporting Okay, let's dive into this. First, I'll refresh my memory by looking at the documentation for `/sys/module//sections/<section>`. Ah, right, that's where we get the memory address for a loaded module's section. The documentation notes that for sections like `.data..percpu`, the address reported is for the boot CPU's instance. That's a key detail to keep in mind, specifically "the instance of the boot CPU". Now, I need to see how* that address is determined, so I'll check the `load_module` code. Okay, here's the relevant snippet: ```c /* The percpu ELF section is a template; report the boot CPU instance. */ if (info->index.pcpu) info->sechdrs[info->index.pcpu].sh_addr = (unsigned long)per_cpu_ptr(mod->percpu, get_boot_cpu_id()); ``` Aha! It's using `per_cpu_ptr` with `get_boot_cpu_id()` to get the address of the per-CPU data, explicitly targeting the boot CPU's instance. This makes perfect sense; the system reports the boot CPU address because the percpu section is a template. This provides the correct method to calculate the address, as expected. I'll remember this for any future investigations related to module loading and section address mapping.
42/3	2026/09/07 08:44	tool	grepper	0m Args: { "Expression": "sect_show\|module_sections", "PathPrefix": "kernel/module/" } Results: { "Output": "kernel/module/main.c=2625=static int check_modinfo(struct module mod, struct load_info info, int flags)\n--\nkernel/module/main.c-2650-\nkernel/module/main.c:2651:static int find_module_sections(struct module mod, struct load_info info)\nkernel/module/main.c-2652-{\n--\nkernel/module/main.c=2919=static int allocate_codetag_sections(struct load_info info)\n--\nkernel/module/main.c-2931-\t\tif (WARN_ON(!dest)) {\nkernel/module/main.c:2932:\t\t\tcodetag_free_module_sections(info-\u003emod);\nkernel/module/main.c-2933-\t\t\treturn -EINVAL;\n--\nkernel/module/main.c-2938-\t\tif (IS_ERR(dest)) {\nkernel/module/main.c:2939:\t\t\tcodetag_free_module_sections(info-\u003emod);\nkernel/module/main.c-2940-\t\t\treturn PTR_ERR(dest);\n--\nkernel/module/main.c=2954=static struct module layout_and_allocate(struct load_info info, int flags)\n--\nkernel/module/main.c-2997-\tif (err) {\nkernel/module/main.c:2998:\t\tcodetag_free_module_sections(info-\u003emod);\nkernel/module/main.c-2999-\t\treturn ERR_PTR(err);\n--\nkernel/module/main.c=3011=static void module_deallocate(struct module mod, struct load_info info)\n--\nkernel/module/main.c-3014-\tmodule_arch_freeing_init(mod);\nkernel/module/main.c:3015:\tcodetag_free_module_sections(mod);\nkernel/module/main.c-3016-\n--\nkernel/module/main.c=3442=static int load_module(struct load_info info, const char __user uargs,\n--\nkernel/module/main.c-3516-\t /\nkernel/module/main.c:3517:\terr = find_module_sections(mod, info);\nkernel/module/main.c-3518-\tif (err)\n" }
43/3	2026/09/07 08:44	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 17564 output: 26 thoughts: 28 Thoughts: Here's my thinking: Investigating the System Filesystem Interface for Module Sections Okay, so I need to understand how the `sections` attributes within the sysfs are generated for kernel modules. My first instinct, given my experience, is to dig into the kernel source code, specifically around the module handling and sysfs interactions. I'm going to start by looking for a file like `kernel/module/sysfs.c` (or something similarly named, related to modules and sysfs) as that's where I'd expect to find the core logic for exposing module information through the system filesystem. That location is usually where low-level implementations and attributes would be defined. I'm expecting to find the key function or structure involved in creating those sysfs entries for the module sections themselves. Let's start there.
44/3	2026/09/07 08:44	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-3586-\nkernel/module/main.c:3587:\t/ Link in to sysfs. /\nkernel/module/main.c:3588:\terr = mod_sysfs_setup(mod, info, mod-\u003ekp, mod-\u003enum_kp);\nkernel/module/main.c-3589-\tif (err \u003c 0)\n--\nkernel/module/main.c-3594-\t\tif (err \u003c 0)\nkernel/module/main.c:3595:\t\t\tgoto sysfs_cleanup;\nkernel/module/main.c-3596-\t}\n--\nkernel/module/main.c-3612-\t\tfree_module_elf(mod);\nkernel/module/main.c:3613: sysfs_cleanup:\nkernel/module/main.c:3614:\tmod_sysfs_teardown(mod);\nkernel/module/main.c-3615- 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=65=static int add_sect_attrs(struct module mod, const struct load_info info)\n--\nkernel/module/sysfs.c-96-\t\t\tcontinue;\nkernel/module/sysfs.c:97:\t\tsysfs_bin_attr_init(sattr);\nkernel/module/sysfs.c-98-\t\tsattr-\u003eattr.name =\n--\nkernel/module/sysfs.c-110-\nkernel/module/sysfs.c:111:\tret = sysfs_create_group(\u0026mod-\u003emkobj.kobj, \u0026sect_attrs-\u003egrp);\nkernel/module/sysfs.c-112-\tif (ret)\n--\nkernel/module/sysfs.c=122=static void remove_sect_attrs(struct module mod)\n--\nkernel/module/sysfs.c-124-\tif (mod-\u003esect_attrs) {\nkernel/module/sysfs.c:125:\t\tsysfs_remove_group(\u0026mod-\u003emkobj.kobj,\nkernel/module/sysfs.c-126-\t\t\t\t \u0026mod-\u003esect_attrs-\u003egrp);\n--\nkernel/module/sysfs.c=151=static int add_notes_attrs(struct module mod, const struct load_info info)\n--\nkernel/module/sysfs.c-186-\t\tif (info-\u003esechdrs[i].sh_type == SHT_NOTE) {\nkernel/module/sysfs.c:187:\t\t\tsysfs_bin_attr_init(nattr);\nkernel/module/sysfs.c-188-\t\t\tnattr-\u003eattr.name = mod-\u003esect_attrs-\u003eattrs[loaded].attr.name;\n--\nkernel/module/sysfs.c-191-\t\t\tnattr-\u003eprivate = (void )info-\u003esechdrs[i].sh_addr;\nkernel/module/sysfs.c:192:\t\t\tnattr-\u003eread = sysfs_bin_attr_simple_read;\nkernel/module/sysfs.c-193-\t\t\t(gattr++) = nattr++;\n--\nkernel/module/sysfs.c-197-\nkernel/module/sysfs.c:198:\tret = sysfs_create_group(\u0026mod-\u003emkobj.kobj, \u0026notes_attrs-\u003egrp);\nkernel/module/sysfs.c-199-\tif (ret)\n--\nkernel/module/sysfs.c=210=static void remove_notes_attrs(struct module mod)\n--\nkernel/module/sysfs.c-212-\tif (mod-\u003enotes_attrs) {\nkernel/module/sysfs.c:213:\t\tsysfs_remove_group(\u0026mod-\u003emkobj.kobj,\nkernel/module/sysfs.c-214-\t\t\t\t \u0026mod-\u003enotes_attrs-\u003egrp);\n--\nkernel/module/sysfs.c=237=static void del_usage_links(struct module mod)\n--\nkernel/module/sysfs.c-243-\tlist_for_each_entry(use, \u0026mod-\u003etarget_list, target_list)\nkernel/module/sysfs.c:244:\t\tsysfs_remove_link(use-\u003etarget-\u003eholders_dir, mod-\u003ename);\nkernel/module/sysfs.c-245-\tmutex_unlock(\u0026module_mutex);\n--\nkernel/module/sysfs.c=249=static int add_usage_links(struct module mod)\n--\nkernel/module/sysfs.c-256-\tlist_for_each_entry(use, \u0026mod-\u003etarget_list, target_list) {\nkernel/module/sysfs.c:257:\t\tret = sysfs_create_link(use-\u003etarget-\u003eholders_dir,\nkernel/module/sysfs.c-258-\t\t\t\t\t\u0026mod-\u003emkobj.kobj, mod-\u003ename);\n--\nkernel/module/sysfs.c=269=static void module_remove_modinfo_attrs(struct module mod, int end)\n--\nkernel/module/sysfs.c-279-\t\t\tbreak;\nkernel/module/sysfs.c:280:\t\tsysfs_remove_file(\u0026mod-\u003emkobj.kobj, \u0026attr-\u003eattr);\nkernel/module/sysfs.c-281-\t\tif (attr-\u003efree)\n--\nkernel/module/sysfs.c=287=static int module_add_modinfo_attrs(struct module mod)\n--\nkernel/module/sysfs.c-303-\t\t\tmemcpy(temp_attr, attr, sizeof(temp_attr));\nkernel/module/sysfs.c:304:\t\t\tsysfs_attr_init(\u0026temp_attr-\u003eattr);\nkernel/module/sysfs.c:305:\t\t\terror = sysfs_create_file(\u0026mod-\u003emkobj.kobj,\nkernel/module/sysfs.c-306-\t\t\t\t\t\t \u0026temp_attr-\u003eattr);\n--\nkernel/module/sysfs.c=323=static void mod_kobject_put(struct module mod)\n--\nkernel/module/sysfs.c-331-\nkernel/module/sysfs.c:332:static int mod_sysfs_init(struct module mod)\nkernel/module/sysfs.c-333-{\n--\nkernel/module/sysfs.c-337-\tif (!module_kset) {\nkernel/module/sysfs.c:338:\t\tpr_err(\"%s: module sysfs not initialized\\n\", mod-\u003ename);\nkernel/module/sysfs.c-339-\t\terr = -EINVAL;\n--\nkernel/module/sysfs.c-363-\nkernel/module/sysfs.c:364:int mod_sysfs_setup(struct module mod,\nkernel/module/sysfs.c-365-\t\t const struct load_info info,\n--\nkernel/module/sysfs.c-370-\nkernel/module/sysfs.c:371:\terr = mod_sysfs_init(mod);\nkernel/module/sysfs.c-372-\tif (err)\n--\nkernel/module/sysfs.c-380-\nkernel/module/sysfs.c:381:\terr = module_param_sysfs_setup(mod, kparam, num_params);\nkernel/module/sysfs.c-382-\tif (err)\n--\nkernel/module/sysfs.c-409-out_unreg_param:\nkernel/module/sysfs.c:410:\tmodule_param_sysfs_remove(mod);\nkernel/module/sysfs.c-411-out_unreg_holders:\n--\nkernel/module/sysfs.c-418-\nkernel/module/sysfs.c:419:static void mod_sysfs_fini(struct module mod)\nkernel/module/sysfs.c-420-{\n--\nkernel/module/sysfs.c-425-\nkernel/module/sysfs.c:426:void mod_sysfs_teardown(struct module mod)\nkernel/module/sysfs.c-427-{\n--\nkernel/module/sysfs.c-429-\tmodule_remove_modinfo_attrs(mod, -1);\nkernel/module/sysfs.c:430:\tmodule_param_sysfs_remove(mod);\nkernel/module/sysfs.c-431-\tkobject_put(mod-\u003emkobj.drivers_dir);\nkernel/module/sysfs.c-432-\tkobject_put(mod-\u003eholders_dir);\nkernel/module/sysfs.c:433:\tmod_sysfs_fini(mod);\nkernel/module/sysfs.c-434-}\n" }
45/3	2026/09/07 08:44	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 21081 output: 35 thoughts: 21 Thoughts: Here's a summary of my thought process, as requested: Diving into `sysfs.c` Okay, time to dig into some code. I need to take a look at the `kernel/module/sysfs.c` file, specifically lines 65 through 105. That's a relatively focused section, so hopefully, it won't be too dense. I'm expecting this to deal with module-related sysfs entries, likely initialization or attribute creation, given the context. Let's see what kind of data structures they're working with in that section and what functions are being called. I'm especially interested in understanding how module information is exposed through the sysfs interface and any potential pitfalls in that area. Should be an interesting read.
46/3	2026/09/07 08:44	tool	read-file	0m Args: { "File": "kernel/module/sysfs.c", "FirstLine": 60, "LineCount": 55 } Results: { "Contents": " 60:\t\t\tkfree((bin_attr)-\u003eattr.name);\n 61:\t\tkfree(sect_attrs-\u003egrp.bin_attrs);\n 62:\t\tkfree(sect_attrs);\n 63:\t}\n 64:\t\n 65:\tstatic int add_sect_attrs(struct module mod, const struct load_info info)\n 66:\t{\n 67:\t\tstruct module_sect_attrs sect_attrs;\n 68:\t\tconst struct bin_attribute *gattr;\n 69:\t\tstruct bin_attribute sattr;\n 70:\t\tunsigned int nloaded = 0, i;\n 71:\t\tint ret;\n 72:\t\n 73:\t\t/* Count loaded sections and allocate structures /\n 74:\t\tfor (i = 0; i \u003c info-\u003ehdr-\u003ee_shnum; i++)\n 75:\t\t\tif (!sect_empty(\u0026info-\u003esechdrs[i]))\n 76:\t\t\t\tnloaded++;\n 77:\t\tsect_attrs = kzalloc_flex(sect_attrs, attrs, nloaded);\n 78:\t\tif (!sect_attrs)\n 79:\t\t\treturn -ENOMEM;\n 80:\t\n 81:\t\tgattr = kzalloc_objs(gattr, nloaded + 1);\n 82:\t\tif (!gattr) {\n 83:\t\t\tkfree(sect_attrs);\n 84:\t\t\treturn -ENOMEM;\n 85:\t\t}\n 86:\t\n 87:\t\t/ Setup section attributes. /\n 88:\t\tsect_attrs-\u003egrp.name = \"sections\";\n 89:\t\tsect_attrs-\u003egrp.bin_attrs = gattr;\n 90:\t\n 91:\t\tsattr = \u0026sect_attrs-\u003eattrs[0];\n 92:\t\tfor (i = 0; i \u003c info-\u003ehdr-\u003ee_shnum; i++) {\n 93:\t\t\tElf_Shdr sec = \u0026info-\u003esechdrs[i];\n 94:\t\n 95:\t\t\tif (sect_empty(sec))\n 96:\t\t\t\tcontinue;\n 97:\t\t\tsysfs_bin_attr_init(sattr);\n 98:\t\t\tsattr-\u003eattr.name =\n 99:\t\t\t\tkstrdup(info-\u003esecstrings + sec-\u003esh_name, GFP_KERNEL);\n 100:\t\t\tif (!sattr-\u003eattr.name) {\n 101:\t\t\t\tret = -ENOMEM;\n 102:\t\t\t\tgoto out;\n 103:\t\t\t}\n 104:\t\t\tsattr-\u003eread = module_sect_read;\n 105:\t\t\tsattr-\u003eprivate = (void )sec-\u003esh_addr;\n 106:\t\t\tsattr-\u003esize = MODULE_SECT_READ_SIZE;\n 107:\t\t\tsattr-\u003eattr.mode = 0400;\n 108:\t\t\t(gattr++) = sattr++;\n 109:\t\t}\n 110:\t\n 111:\t\tret = sysfs_create_group(\u0026mod-\u003emkobj.kobj, \u0026sect_attrs-\u003egrp);\n 112:\t\tif (ret)\n 113:\t\t\tgoto out;\n 114:\t\n" }
47/3	2026/09/07 08:44	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 22110 output: 35 thoughts: 52 Thoughts: Here's my analysis of the provided code snippet and the surrounding context: Analyzing the Module Section Initialization Okay, so I'm looking at how a section's private data is being initialized within the kernel's module system. Specifically, I see this assignment: `sattr->private = (void )sec->sh_addr;`. This tells me that the `private` member of a section attribute (`sattr`) is being set to the start address (`sh_addr`) of a section (`sec`). That seems straightforward enough – we're essentially linking the section's memory address to a private data structure. This `private` pointer is probably for internal use, for the kernel to reference the section in its own bookkeeping, or perhaps for some kind of specialized handling. Now, I need to understand why* this is happening, and what the `module_sect_read` function is doing in relation. My next step would be to consult the related source code. I know that the function `module_sect_read` is relevant to this section, and my immediate suspicion is that it is reading data that resides in the sections. To get a better grasp of the situation, I need to check the code that surrounds this initialization. Lines 30-59 in `kernel/module/sysfs.c` are probably where the action is. By examining that block of code, I can hopefully see the surrounding logic: how these `sattr` structs are being used, what `sec` refers to (is it a section header?), and what data is being read or manipulated based on the pointer initialized here. I'm guessing that these lines contain the core of the module section handling within the `sysfs` interface. This is going to give me the whole picture.
48/3	2026/09/07 08:44	tool	read-file	0m Args: { "File": "kernel/module/sysfs.c", "FirstLine": 30, "LineCount": 35 } Results: { "Contents": " 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 50:\t\tmemcpy(buf, bounce, count);\n 51:\t\n 52:\t\treturn count;\n 53:\t}\n 54:\t\n 55:\tstatic void free_sect_attrs(struct module_sect_attrs sect_attrs)\n 56:\t{\n 57:\t\tconst struct bin_attribute const bin_attr;\n 58:\t\n 59:\t\tfor (bin_attr = sect_attrs-\u003egrp.bin_attrs; bin_attr; bin_attr++)\n 60:\t\t\tkfree((bin_attr)-\u003eattr.name);\n 61:\t\tkfree(sect_attrs-\u003egrp.bin_attrs);\n 62:\t\tkfree(sect_attrs);\n 63:\t}\n 64:\t\n" }
49/3	2026/09/07 08:44	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 23082 output: 27 thoughts: 22 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: Investigating `sect_empty` Functionality Alright, let's delve deeper into this `sect_empty` function. My initial investigation is complete, but I need to understand its full implications. The behavior thus far is interesting, but I need to identify exactly how it's being used within the code base. I'll need to locate every instance of `sect_empty` to understand the different contexts in which it operates. This will allow me to build a more comprehensive mental model of this function's purpose and any potential vulnerabilities or optimizations that are present. The documentation, if it exists, is probably a good start, but I know it is always best to double check and find how it is actually being used. Time to get to it.
50/3	2026/09/07 08:44	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=65=static int add_sect_attrs(struct module mod, const struct load_info info)\n--\nkernel/module/sysfs.c-74-\tfor (i = 0; i \u003c info-\u003ehdr-\u003ee_shnum; i++)\nkernel/module/sysfs.c:75:\t\tif (!sect_empty(\u0026info-\u003esechdrs[i]))\nkernel/module/sysfs.c-76-\t\t\tnloaded++;\n--\nkernel/module/sysfs.c-94-\nkernel/module/sysfs.c:95:\t\tif (sect_empty(sec))\nkernel/module/sysfs.c-96-\t\t\tcontinue;\n--\nkernel/module/sysfs.c=151=static int add_notes_attrs(struct module mod, const struct load_info info)\n--\nkernel/module/sysfs.c-161-\tfor (i = 0; i \u003c info-\u003ehdr-\u003ee_shnum; i++)\nkernel/module/sysfs.c:162:\t\tif (!sect_empty(\u0026info-\u003esechdrs[i]) \u0026\u0026\nkernel/module/sysfs.c-163-\t\t info-\u003esechdrs[i].sh_type == SHT_NOTE)\n--\nkernel/module/sysfs.c-183-\tfor (loaded = i = 0; i \u003c info-\u003ehdr-\u003ee_shnum; ++i) {\nkernel/module/sysfs.c:184:\t\tif (sect_empty(\u0026info-\u003esechdrs[i]))\nkernel/module/sysfs.c-185-\t\t\tcontinue;\n" }
51/3	2026/09/07 08:44	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 23960 output: 35 thoughts: 20 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: Diving into Internal Module Structures Okay, so I'm troubleshooting something related to module management. My first instinct is to drill down into the core data structures that underpin the kernel's module handling. The `kernel/module/internal.h` header is the logical place to start – it's where the critical internal definitions reside. Specifically, I'm thinking I need to zero in around line 368. That area likely defines a key structure or macro I need to understand, perhaps related to symbol tables, module linking, or state transitions. I need to refresh my memory on what that section actually contains. Let's see what's lurking in the code.
52/3	2026/09/07 08:45	tool	read-file	0m Args: { "File": "kernel/module/internal.h", "FirstLine": 365, "LineCount": 20 } 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 380:\t\t\t struct kernel_param kparam, unsigned int num_params);\n 381:\tvoid mod_sysfs_teardown(struct module mod);\n 382:\tvoid init_param_lock(struct module mod);\n 383:\t#else /* !CONFIG_SYSFS /\n 384:\tstatic inline int mod_sysfs_setup(struct module mod,\n" }
53/3	2026/09/07 08:45	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 24593 output: 29 thoughts: 1166 Thoughts: Analyzing the Implications of This Patch Series Okay, let's break this down. First, the core issue seems to be around how per-CPU data sections (`.data..percpu`) are handled, specifically ensuring they are properly exposed via sysfs. I can see that the previous method of stripping `SHF_ALLOC` from these sections was leading to `sect_empty` incorrectly returning true. This, in turn, prevented the creation of the `/sys/module/<mod>/sections/.data..percpu` entry. Now, by retaining `SHF_ALLOC` and correctly setting the address, we are making sure the expected sysfs entry shows the correct boot CPU percpu address. Excellent. Now, let me systematically address the KMSAN implications. There are four key criteria to watch for, so let me quickly review those, as I know them quite well: uninitialized kernel structures in userspace, conditional logic on uninitialized variables, uninitialized fields in allocations, and potential access to uninitialized bytes through bounds checks. Okay, let's step through the patch series item by item: 1. `Documentation/ABI/testing/sysfs-module`: This is only documentation and poses no risk. 2. `include/linux/module.h`: The introduction of `MOD_STANDALONE` is fine. It does not seem immediately relevant to KMSAN. 3. `kernel/module/internal.h`: Defining `SH_ENTSIZE_STANDALONE` based on `MOD_STANDALONE` is also harmless. 4. `kernel/module/kallsyms.c`: Removing the special case for `pcpundx` is now safe because the underlying issue with `SHF_ALLOC` is fixed. The rest of the changes are not significant. 5. `kernel/module/main.c`: Here's where we need to be more careful. * `apply_relocations`: Restoring the logic here to check `SHF_ALLOC` should be safe, as it correctly handles the allocations now. * `__layout_sections`: Skipping standalone sections (`s->sh_entsize != ~0UL`) looks right. The codetag handling removal is also ok. * `layout_sections`: Moving the initialization of `sh_entsize` is fine, given the context. * `move_module`: Skipping based on `SHF_ALLOC` and `SH_ENTSIZE_STANDALONE` seems correct. Removing codetag allocation and cleanup on error here appears correct, as it is moved elsewhere. * `allocate_codetag_sections`: This is interesting. The key here is the `memcpy` or `memset`. If `shdr->sh_type != SHT_NOBITS`, `memcpy` will copy initialized data into the section. Otherwise, `memset` initializes the region to zero. After this, `shdr->sh_addr` is set. Given the presence of explicit initialization, it seems safe. * `layout_and_allocate`: Initializing `sh_entsize` to `~0UL` for all sections and then conditionally setting it to `SH_ENTSIZE_STANDALONE` for `info->index.pcpu` makes sense. The calls to `allocate_codetag_sections`, `layout_sections`, `layout_symtab`, and `move_module` (with error handling that frees the codetag sections) seem correct. * `load_module`: The crucial part: setting `info->sechdrs[info->index.pcpu].sh_addr` to `per_cpu_ptr(mod->percpu, get_boot_cpu_id())` only happens after `mod->percpu` is allocated by `percpu_modalloc`. Now, let me quickly double-check that `percpu_modalloc` is safe, as this is where the KMSAN risks will be greatest... * Now, I need to check `percpu_modalloc`.
54/3	2026/09/07 08:45	tool	grepper	0m Args: { "Expression": "percpu_modalloc", "PathPrefix": "kernel/module/" } Results: { "Output": "kernel/module/main.c=450=static inline void __percpu mod_percpu(struct module mod)\n--\nkernel/module/main.c-454-\nkernel/module/main.c:455:static int percpu_modalloc(struct module mod, struct load_info info)\nkernel/module/main.c-456-{\n--\nkernel/module/main.c=542=static inline void __percpu mod_percpu(struct module mod)\n--\nkernel/module/main.c-545-}\nkernel/module/main.c:546:static int percpu_modalloc(struct module mod, struct load_info info)\nkernel/module/main.c-547-{\n--\nkernel/module/main.c=3442=static int load_module(struct load_info info, const char __user uargs,\n--\nkernel/module/main.c-3501-\t/* To avoid stressing percpu allocator, do this once we're unique. */\nkernel/module/main.c:3502:\terr = percpu_modalloc(mod, info);\nkernel/module/main.c-3503-\tif (err)\n" }
55/3	2026/09/07 08:45	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 26971 output: 35 thoughts: 21 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: Diving into `percpu_modalloc` Okay, time to get my hands dirty. I'm focusing in on the allocation strategy for per-CPU variables within kernel modules. Specifically, I'm going to revisit `percpu_modalloc` – that's the function I need to understand better. I know it's located in `kernel/module/main.c`, so I'll jump straight there. I need to refresh my understanding of how this handles per-CPU data, especially with respect to the module loading lifecycle. I'm going to look at the interactions with the module loading/unloading paths, memory management and potential issues with locking or race conditions. I suspect there may be a performance bottleneck there that has recently come up in a discussion. Let's start with the code.
56/3	2026/09/07 08:45	tool	read-file	0m Args: { "File": "kernel/module/main.c", "FirstLine": 455, "LineCount": 40 } Results: { "Contents": " 455:\tstatic int percpu_modalloc(struct module mod, struct load_info info)\n 456:\t{\n 457:\t\tElf_Shdr pcpusec = \u0026info-\u003esechdrs[info-\u003eindex.pcpu];\n 458:\t\tunsigned long align = pcpusec-\u003esh_addralign;\n 459:\t\n 460:\t\tif (!pcpusec-\u003esh_size)\n 461:\t\t\treturn 0;\n 462:\t\n 463:\t\tif (align \u003e PAGE_SIZE) {\n 464:\t\t\tpr_warn(\"%s: per-cpu alignment %li \u003e %li\\n\",\n 465:\t\t\t\tmod-\u003ename, align, PAGE_SIZE);\n 466:\t\t\talign = PAGE_SIZE;\n 467:\t\t}\n 468:\t\n 469:\t\tmod-\u003epercpu = __alloc_reserved_percpu(pcpusec-\u003esh_size, align);\n 470:\t\tif (!mod-\u003epercpu) {\n 471:\t\t\tpr_warn(\"%s: Could not allocate %lu bytes percpu data\\n\",\n 472:\t\t\t\tmod-\u003ename, (unsigned long)pcpusec-\u003esh_size);\n 473:\t\t\treturn -ENOMEM;\n 474:\t\t}\n 475:\t\tmod-\u003epercpu_size = pcpusec-\u003esh_size;\n 476:\t\treturn 0;\n 477:\t}\n 478:\t\n 479:\tstatic void percpu_modfree(struct module mod)\n 480:\t{\n 481:\t\tfree_percpu(mod-\u003epercpu);\n 482:\t}\n 483:\t\n 484:\tstatic unsigned int find_pcpusec(struct load_info info)\n 485:\t{\n 486:\t\treturn find_sec(info, \".data..percpu\");\n 487:\t}\n 488:\t\n 489:\tstatic void percpu_modcopy(struct module mod,\n 490:\t\t\t\t const void *from, unsigned long size)\n 491:\t{\n 492:\t\tint cpu;\n 493:\t\n 494:\t\tfor_each_possible_cpu(cpu)\n" }
57/3	2026/09/07 08:45	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 27818 output: 35 thoughts: 12 Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience, presented in the first person: Deep Dive on `percpu_modcopy` Alright, I need to circle back and give `percpu_modcopy` a closer look. I've been focusing on [mention the broader topic you were working on, e.g., memory management, kernel synchronization, etc.], but I realize this function is likely pivotal to the interactions within this system. I should evaluate: * Its purpose: What specific problem does it solve in a per-CPU context? Is it about data copying, modification in-place, synchronization, or something else entirely? * Performance Implications: Considering its per-CPU nature, how does this affect scalability? Does it optimize for cache coherency, or are there potential bottlenecks with frequent modifications? I'll probably want to test this within a multi-core environment. * Alternatives: Are there alternative mechanisms in this architecture or others that are suitable in these scenarios? Are there lock-free approaches that could perform the same task with less overhead? * Potential issues: What are the common issues that can occur? Are there lock-related concerns, race conditions, memory corruption or buffer overflows that could exist? * Safety: I need to understand its exception handling, error cases, and if there are ways to create/trigger undefined behavior. * Integration: How is it used, and where is it used? I must trace its calls from the top-level to all the leaves, and all the things that interact with it. I should compare the use-case with similar systems. Overall, I need a comprehensive understanding of `percpu_modcopy` to validate its role and efficiency in the system. I also want to make sure I am not missing a critical point.
58/3	2026/09/07 08:45	tool	read-file	0m Args: { "File": "kernel/module/main.c", "FirstLine": 490, "LineCount": 20 } Results: { "Contents": " 490:\t\t\t\t const void from, unsigned long size)\n 491:\t{\n 492:\t\tint cpu;\n 493:\t\n 494:\t\tfor_each_possible_cpu(cpu)\n 495:\t\t\tmemcpy(per_cpu_ptr(mod-\u003epercpu, cpu), from, size);\n 496:\t}\n 497:\t\n 498:\tbool __is_module_percpu_address(unsigned long addr, unsigned long can_addr)\n 499:\t{\n 500:\t\tstruct module *mod;\n 501:\t\tunsigned int cpu;\n 502:\t\n 503:\t\tguard(rcu)();\n 504:\t\tlist_for_each_entry_rcu(mod, \u0026modules, list) {\n 505:\t\t\tif (mod-\u003estate == MODULE_STATE_UNFORMED)\n 506:\t\t\t\tcontinue;\n 507:\t\t\tif (!mod-\u003epercpu_size)\n 508:\t\t\t\tcontinue;\n 509:\t\t\tfor_each_possible_cpu(cpu) {\n" }
59/3	2026/09/07 08:45	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 28547 output: 29 thoughts: 20 Thoughts: Here's a summary of my thought process, as requested: Navigating Module Loading with `percpu_modcopy` Okay, so I need to understand how `percpu_modcopy` fits into the `load_module` process. Let's dig in and figure out where the calls to `percpu_modcopy` are happening within the `load_module` function. I want to see exactly how it's being used – is it for data initialization, relocation, or something else entirely? The context will be key here; just seeing the call isn't enough. I need to understand the surrounding code to grasp its purpose within the module loading sequence. I’m thinking there might be something interesting to observe about memory management in module loading.
60/3	2026/09/07 08:45	tool	grepper	0m Args: { "Expression": "percpu_modcopy", "PathPrefix": "kernel/module/" } Results: { "Output": "kernel/module/main.c=484=static unsigned int find_pcpusec(struct load_info info)\n--\nkernel/module/main.c-488-\nkernel/module/main.c:489:static void percpu_modcopy(struct module mod,\nkernel/module/main.c-490-\t\t\t const void from, unsigned long size)\n--\nkernel/module/main.c=556=static unsigned int find_pcpusec(struct load_info info)\n--\nkernel/module/main.c-559-}\nkernel/module/main.c:560:static inline void percpu_modcopy(struct module mod,\nkernel/module/main.c-561-\t\t\t\t const void from, unsigned long size)\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" }
61/3	2026/09/07 08:45	llm	kmsan-evaluator	0m Model: gemini-3.7-flash Args: null Results: null Tokens: input: 29104 output: 257 thoughts: 634 Thoughts: My Analysis of the Patch for KMSAN Implications Okay, so I've been digging into this patch and its potential impact on kernel memory safety, specifically regarding KMSAN (Kernel Memory Sanitizer). The core of this patch seems to be refactoring module loading to properly handle standalone sections like `.data..percpu` and codetag sections. My initial concern was, of course, whether this introduces any uninitialized memory leaks or reads that could be exploited. Let's break down my thought process: First, let's trace the data flow for the `.data..percpu` section. It starts with `percpu_modcopy` which handles copying the relocated data, then `load_module` sets the section address to the boot CPU instance using `per_cpu_ptr`. Later, when a user reads the sysfs entry `/sys/module/<mod>/sections/.data..percpu`, `module_sect_read` formats this boot CPU address ( `sh_addr` which came from that `per_cpu_ptr`) as a string using `scnprintf` into a `bounce` buffer. And that data gets copied to userspace. My first check was for uninitialized memory in that `bounce` buffer. However, the `scnprintf` formatting ensures that every byte within `bounce` is explicitly written. Then, `memcpy` only copies up to `count` bytes. So, no uninitialized data leaks to userspace through that vector. Next, I looked at `allocate_codetag_sections`, which uses `memcpy` or `memset` depending on `SHT_NOBITS`. That looks safe too; the data is initialized. And the `alloc_tag.c` part just reorders function definitions and handles error cleanup - no uninitialized memory usage there. My conclusion is: this patch is not introducing any new avenues for uninitialized memory use or leaks. It's really just restructuring module loading, making sure that sections like `.data..percpu` get correctly represented in sysfs, including the correct boot CPU address. Now, let's contrast KASAN and KMSAN. KASAN is the standard sanitizer that looks for out-of-bounds access, use-after-free, allocation errors, etc. KMSAN, on the other hand, specifically focuses on reads of uninitialized memory (stack, heap, pages), and it prevents the leakage of uninitialized data or padding to userspace. Given this patch's scope, the primary concern would be KMSAN, as that's where uninitialized memory would cause issues. But, because everything is explicitly initialized or formatted before being exposed, KMSAN is not needed here. The patch doesn't change what's being initialized or expose any new variables. Standard sanitizers (KASAN) are sufficient because the patch deals with buffer sizes, memory allocation, and copy operations that are already checked by standard sanitizers. Therefore, my assessment is `NeedsKMSAN=false`. The reasoning is straightforward: the patch doesn't introduce any new uninitialized memory reads or leaks. All data is initialized before use, either directly or through formatted output. Standard sanitizers, like KASAN, are sufficient to address any potential memory safety concerns introduced by this patch's refactoring and cleanup.
62/3	2026/09/07 08:45	tool	set-results	0m Args: { "KMSANReasoning": "The patch refactors module section layout and allocation to handle standalone sections (such as `.data..percpu` and codetag sections). Specifically:\n1. `.data..percpu` retains its `SHF_ALLOC` flag and is marked as `SH_ENTSIZE_STANDALONE`, allowing it to be properly exposed via `/sys/module//sections/\u003csection\u003e` pointing to the boot CPU instance.\n2. Codetag section allocation is moved earlier into a dedicated helper (`allocate_codetag_sections`), with proper fallback to regular section allocation if codetag memory is exhausted.\n3. Copied memory is explicitly initialized using `memcpy` or `memset` for NOBITS sections, and sysfs reading formats addresses safely into bounded buffers via `scnprintf`.\n4. No uninitialized variables, struct paddings, or buffers are read or copied to userspace.\n\nAny potential bugs from these changes (such as memory management errors, out-of-bounds access during ELF parsing, or error-path resource cleanup) are covered by KASAN and standard kernel debugging facilities. A dedicated KMSAN run is not needed.", "NeedsKMSAN": false } Results:* { "KMSANReasoning": "The patch refactors module section layout and allocation to handle standalone sections (such as `.data..percpu` and codetag sections). Specifically:\n1. `.data..percpu` retains its `SHF_ALLOC` flag and is marked as `SH_ENTSIZE_STANDALONE`, allowing it to be properly exposed via `/sys/module/*/sections/\u003csection\u003e` pointing to the boot CPU instance.\n2. Codetag section allocation is moved earlier into a dedicated helper (`allocate_codetag_sections`), with proper fallback to regular section allocation if codetag memory is exhausted.\n3. Copied memory is explicitly initialized using `memcpy` or `memset` for NOBITS sections, and sysfs reading formats addresses safely into bounded buffers via `scnprintf`.\n4. No uninitialized variables, struct paddings, or buffers are read or copied to userspace.\n\nAny potential bugs from these changes (such as memory management errors, out-of-bounds access during ELF parsing, or error-path resource cleanup) are covered by KASAN and standard kernel debugging facilities. A dedicated KMSAN run is not needed.", "NeedsKMSAN": false }

LLM Calls Summary:
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Tool Calls Summary:
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