AI Trajectory

Trajectory: (Expand/Collapse All)
Seq	Timestamp	Type	Name	Duration
0/0	2026/09/15 13:03	flow	patch-triage	13m Args: null Results: { "EnableConfigs": [ "COREDUMP", "IO_URING" ], "FocusSymbols": [ "coredump_parse", "coredump_close_files", "coredump_finish", "proc_dostring_coredump", "vfs_coredump", "io_wq_exit_start" ], "KMSANReasoning": "The patch series addresses concurrency, race conditions, NULL pointer dereferences, and use-after-free issues in the coredump subsystem, io_uring worker exit, and process cloning:\n1. fs/coredump.c: Introduces `core_pattern_lock` spinlock and local stack buffers (`pattern[CORENAME_MAX_SIZE]`) to safely copy and validate `core_pattern` during sysctl read/write and coredump parsing. Strings are copied and null-terminated via `strscpy()`, and all string functions (`strlen`, `strncmp`, `name_contains_dotdot`) operate strictly within null-terminated bounds. No uninitialized bytes are read, branched upon, or leaked to userspace.\n2. fs/coredump.c: Handles tasks without file tables (e.g. vhost workers) to prevent NULL pointer dereferences, and wraps thread wakeups in `coredump_finish()` with `guard(rcu)()` to prevent use-after-free bugs.\n3. include/linux/sched/signal.h \u0026 kernel/fork.c: Adjusts signal pending checks during core dumps and aborts fork/clone if core dumping is in progress.\n4. io_uring/io-wq.c: Adds a memory barrier (`smp_mb__after_atomic()`) to fix a concurrency race.\n\nThese changes deal with locking, concurrency, UAF, and NULL pointer dereferences, all of which are covered by KASAN and LOCKDEP. No uninitialized memory accesses or info-leaks are introduced or exposed, so a dedicated KMSAN session is not warranted.", "NeedsKMSAN": false, "Reasoning": "The patch series modifies core kernel execution paths in fs/coredump.c, include/linux/sched/signal.h, kernel/fork.c, and io_uring/io-wq.c. Changes include synchronizing core_pattern reads/writes with a new spinlock (core_pattern_lock), guarding against NULL current-\u003efiles during coredump file teardown, adding RCU protection during thread completion wakeups in coredump_finish, refining signal_pending() for PF_DUMPCORE tasks, and adding memory barrier synchronization in io_wq_exit_start(). These modifications directly alter synchronization and lifecycle flow in reachable core subsystems and warrant fuzzing.", "WorthFuzzing": true }
1/1	2026/09/15 13:03	action	read-patch-diff	0m Args: null Results: { "PatchDiff": "commit b72263f75d9eddb2a371f65484a2df9bc0431c3d\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate: Tue Sep 15 13:03:07 2026 +0000\n\n syz-cluster: applied patch under review\n\ndiff --git a/fs/coredump.c b/fs/coredump.c\nindex 1fba3fed1a07b..20cd95786dbe2 100644\n--- a/fs/coredump.c\n+++ b/fs/coredump.c\n@@ -86,6 +86,8 @@ static int core_uses_pid;\n static unsigned int core_pipe_limit;\n static unsigned int core_sort_vma;\n static char core_pattern[CORENAME_MAX_SIZE] = \"core\";\n+/* Taken around every copy in and out of core_pattern. /\n+static DEFINE_SPINLOCK(core_pattern_lock);\n static int core_name_size = CORENAME_MAX_SIZE;\n unsigned int core_file_note_size_limit = CORE_FILE_NOTE_SIZE_DEFAULT;\n static atomic_t core_pipe_count = ATOMIC_INIT(0);\n@@ -241,11 +243,16 @@ static bool coredump_parse(struct core_name cn, struct coredump_params cprm,\n \t\t\t size_t argv, int argc)\n {\n \tconst struct cred cred = current_cred();\n-\tconst char pat_ptr = core_pattern;\n+\tchar pattern[CORENAME_MAX_SIZE];\n+\tconst char pat_ptr = pattern;\n \tbool was_space = false;\n \tint pid_in_pattern = 0;\n \tint err = 0;\n \n+\t/ The sysctl handler may be publishing a new pattern. /\n+\tscoped_guard(spinlock, \u0026core_pattern_lock)\n+\t\tstrscpy(pattern, core_pattern);\n+\n \tcprm-\u003emask = COREDUMP_KERNEL;\n \tif (core_pipe_limit)\n \t\tcprm-\u003emask \|= COREDUMP_WAIT;\n@@ -579,7 +586,11 @@ static bool coredump_close_files(struct core_state core_state)\n \t/* Use the dumper's real creds not the overridden ones. /\n \tscoped_with_creds(current_real_cred()) {\n \t\tio_uring_task_cancel();\n-\t\tswitch_files_struct(current, files);\n+\t\t/ The dumper itself may be a vhost worker without a table. /\n+\t\tif (current-\u003efiles)\n+\t\t\tswitch_files_struct(current, files);\n+\t\telse\n+\t\t\tput_files_struct(files);\n \t}\n \n \tcoredump_wait_inactive(core_state);\n@@ -598,6 +609,8 @@ static void coredump_finish(enum coredump_state state)\n \tcurrent-\u003esignal-\u003ecore_state = NULL;\n \tspin_unlock_irq(\u0026current-\u003esighand-\u003esiglock);\n \n+\t/ A released thread may exit and be freed before it is woken. /\n+\tguard(rcu)();\n \twhile ((curr = next) != NULL) {\n \t\tnext = curr-\u003enext;\n \t\ttask = curr-\u003etask;\n@@ -1684,11 +1697,11 @@ void validate_coredump_safety(void)\n \t}\n }\n \n-static inline bool check_coredump_socket(void)\n+static inline bool check_coredump_socket(const char pattern)\n {\n \tconst char p;\n \n-\tif (core_pattern[0] != '@')\n+\tif (pattern[0] != '@')\n \t\treturn true;\n \n \t/\n@@ -1700,16 +1713,16 @@ static inline bool check_coredump_socket(void)\n \t\treturn false;\n \n \t/* Must be an absolute path... /\n-\tif (core_pattern[1] != '/') {\n+\tif (pattern[1] != '/') {\n \t\t/ ... or the socket request protocol... /\n-\t\tif (core_pattern[1] != '@')\n+\t\tif (pattern[1] != '@')\n \t\t\treturn false;\n \t\t/ ... and if so must be an absolute path. /\n-\t\tif (core_pattern[2] != '/')\n+\t\tif (pattern[2] != '/')\n \t\t\treturn false;\n-\t\tp = \u0026core_pattern[2];\n+\t\tp = \u0026pattern[2];\n \t} else {\n-\t\tp = \u0026core_pattern[1];\n+\t\tp = \u0026pattern[1];\n \t}\n \n \t/ The path obviously cannot exceed UNIX_PATH_MAX. /\n@@ -1717,7 +1730,7 @@ static inline bool check_coredump_socket(void)\n \t\treturn false;\n \n \t/ Must not contain \"..\" in the path. /\n-\tif (name_contains_dotdot(core_pattern))\n+\tif (name_contains_dotdot(pattern))\n \t\treturn false;\n \n \treturn true;\n@@ -1726,27 +1739,34 @@ static inline bool check_coredump_socket(void)\n static int proc_dostring_coredump(const struct ctl_table table, int write,\n \t\t void buffer, size_t lenp, loff_t ppos)\n {\n+\tchar pattern[CORENAME_MAX_SIZE];\n+\tconst struct ctl_table tmp = {\n+\t\t.procname\t= table-\u003eprocname,\n+\t\t.data\t\t= pattern,\n+\t\t.maxlen\t\t= sizeof(pattern),\n+\t};\n+\tbool changed = false;\n \tint error;\n-\tssize_t retval;\n-\tchar old_core_pattern[CORENAME_MAX_SIZE];\n-\n-\tif (!write)\n-\t\treturn proc_dostring(table, write, buffer, lenp, ppos);\n \n-\tretval = strscpy(old_core_pattern, core_pattern, CORENAME_MAX_SIZE);\n+\t/ Work on a copy, proc_dostring() appends at ppos. /\n+\tscoped_guard(spinlock, \u0026core_pattern_lock)\n+\t\tstrscpy(pattern, core_pattern);\n \n-\terror = proc_dostring(table, write, buffer, lenp, ppos);\n-\tif (error)\n+\terror = proc_dostring(\u0026tmp, write, buffer, lenp, ppos);\n+\tif (error \|\| !write)\n \t\treturn error;\n \n-\tif (!check_coredump_socket()) {\n-\t\tstrscpy(core_pattern, old_core_pattern, retval + 1);\n+\tif (!check_coredump_socket(pattern))\n \t\treturn -EINVAL;\n-\t}\n \n-\tif (strncmp(old_core_pattern, core_pattern, CORENAME_MAX_SIZE))\n+\t/* Publish the validated pattern whole. /\n+\tscoped_guard(spinlock, \u0026core_pattern_lock) {\n+\t\tchanged = strncmp(pattern, core_pattern, CORENAME_MAX_SIZE);\n+\t\tstrscpy(core_pattern, pattern);\n+\t}\n+\tif (changed)\n \t\tvalidate_coredump_safety();\n-\treturn error;\n+\treturn 0;\n }\n \n static const unsigned int core_file_note_size_min = CORE_FILE_NOTE_SIZE_DEFAULT;\ndiff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h\nindex 70067ccfe2ba4..3a7ff3416e572 100644\n--- a/include/linux/sched/signal.h\n+++ b/include/linux/sched/signal.h\n@@ -386,6 +386,11 @@ static inline int task_sigpending(struct task_struct p)\n \treturn unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING));\n }\n \n+static inline int __fatal_signal_pending(struct task_struct p)\n+{\n+\treturn unlikely(sigismember(\u0026p-\u003epending.signal, SIGKILL));\n+}\n+\n static inline int signal_pending(struct task_struct p)\n {\n \t/\n@@ -395,12 +400,12 @@ static inline int signal_pending(struct task_struct p)\n \t /\n \tif (unlikely(test_tsk_thread_flag(p, TIF_NOTIFY_SIGNAL)))\n \t\treturn 1;\n-\treturn task_sigpending(p);\n-}\n-\n-static inline int __fatal_signal_pending(struct task_struct p)\n-{\n-\treturn unlikely(sigismember(\u0026p-\u003epending.signal, SIGKILL));\n+\tif (!task_sigpending(p))\n+\t\treturn 0;\n+\t/* A coredumping task only stops for SIGKILL, see dump_interrupted(). /\n+\tif (unlikely(READ_ONCE(p-\u003eflags) \u0026 PF_DUMPCORE))\n+\t\treturn __fatal_signal_pending(p);\n+\treturn 1;\n }\n \n static inline int fatal_signal_pending(struct task_struct p)\ndiff --git a/io_uring/io-wq.c b/io_uring/io-wq.c\nindex 2ca223e47d41f..2a980e86dd940 100644\n--- a/io_uring/io-wq.c\n+++ b/io_uring/io-wq.c\n@@ -1324,6 +1324,8 @@ static bool io_task_work_match(struct callback_head cb, void data)\n void io_wq_exit_start(struct io_wq wq)\n {\n \tset_bit(IO_WQ_BIT_EXIT, \u0026wq-\u003estate);\n+\t/ Pairs with task_work_add() in io_queue_worker_create(). /\n+\tsmp_mb__after_atomic();\n }\n \n static void io_wq_cancel_tw_create(struct io_wq wq)\ndiff --git a/kernel/fork.c b/kernel/fork.c\nindex 10be4a0ecb3f1..bd97fc7b885b4 100644\n--- a/kernel/fork.c\n+++ b/kernel/fork.c\n@@ -2491,8 +2491,8 @@ __latent_entropy struct task_struct copy_process(\n \t\tgoto bad_fork_core_free;\n \t}\n \n-\t/ Let kill terminate clone/fork in the middle /\n-\tif (fatal_signal_pending(current)) {\n+\t/ Let kill or a coredump in progress terminate clone/fork */\n+\tif (fatal_signal_pending(current) \|\| current-\u003esignal-\u003ecore_state) {\n \t\tretval = -EINTR;\n \t\tgoto bad_fork_core_free;\n \t}\n" }
2/1	2026/09/15 13:03	agent	patch-evaluator	2m Model: core Args: null Results: { "EnableConfigs": [ "COREDUMP", "IO_URING" ], "FocusSymbols": [ "coredump_parse", "coredump_close_files", "coredump_finish", "proc_dostring_coredump", "vfs_coredump", "io_wq_exit_start" ], "Reasoning": "The patch series modifies core kernel execution paths in fs/coredump.c, include/linux/sched/signal.h, kernel/fork.c, and io_uring/io-wq.c. Changes include synchronizing core_pattern reads/writes with a new spinlock (core_pattern_lock), guarding against NULL current-\u003efiles during coredump file teardown, adding RCU protection during thread completion wakeups in coredump_finish, refining signal_pending() for PF_DUMPCORE tasks, and adding memory barrier synchronization in io_wq_exit_start(). These modifications directly alter synchronization and lifecycle flow in reachable core subsystems 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 b72263f75d9eddb2a371f65484a2df9bc0431c3d Author: syz-cluster <triage@syzkaller.com> Date: Tue Sep 15 13:03:07 2026 +0000 syz-cluster: applied patch under review diff --git a/fs/coredump.c b/fs/coredump.c index 1fba3fed1a07b..20cd95786dbe2 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -86,6 +86,8 @@ static int core_uses_pid; static unsigned int core_pipe_limit; static unsigned int core_sort_vma; static char core_pattern[CORENAME_MAX_SIZE] = "core"; +/* Taken around every copy in and out of core_pattern. / +static DEFINE_SPINLOCK(core_pattern_lock); static int core_name_size = CORENAME_MAX_SIZE; unsigned int core_file_note_size_limit = CORE_FILE_NOTE_SIZE_DEFAULT; static atomic_t core_pipe_count = ATOMIC_INIT(0); @@ -241,11 +243,16 @@ static bool coredump_parse(struct core_name cn, struct coredump_params cprm, size_t argv, int argc) { const struct cred cred = current_cred(); - const char pat_ptr = core_pattern; + char pattern[CORENAME_MAX_SIZE]; + const char pat_ptr = pattern; bool was_space = false; int pid_in_pattern = 0; int err = 0; + / The sysctl handler may be publishing a new pattern. / + scoped_guard(spinlock, &core_pattern_lock) + strscpy(pattern, core_pattern); + cprm->mask = COREDUMP_KERNEL; if (core_pipe_limit) cprm->mask \|= COREDUMP_WAIT; @@ -579,7 +586,11 @@ static bool coredump_close_files(struct core_state core_state) /* Use the dumper's real creds not the overridden ones. / scoped_with_creds(current_real_cred()) { io_uring_task_cancel(); - switch_files_struct(current, files); + / The dumper itself may be a vhost worker without a table. / + if (current->files) + switch_files_struct(current, files); + else + put_files_struct(files); } coredump_wait_inactive(core_state); @@ -598,6 +609,8 @@ static void coredump_finish(enum coredump_state state) current->signal->core_state = NULL; spin_unlock_irq(&current->sighand->siglock); + / A released thread may exit and be freed before it is woken. / + guard(rcu)(); while ((curr = next) != NULL) { next = curr->next; task = curr->task; @@ -1684,11 +1697,11 @@ void validate_coredump_safety(void) } } -static inline bool check_coredump_socket(void) +static inline bool check_coredump_socket(const char pattern) { const char p; - if (core_pattern[0] != '@') + if (pattern[0] != '@') return true; / @@ -1700,16 +1713,16 @@ static inline bool check_coredump_socket(void) return false; /* Must be an absolute path... / - if (core_pattern[1] != '/') { + if (pattern[1] != '/') { / ... or the socket request protocol... / - if (core_pattern[1] != '@') + if (pattern[1] != '@') return false; / ... and if so must be an absolute path. / - if (core_pattern[2] != '/') + if (pattern[2] != '/') return false; - p = &core_pattern[2]; + p = &pattern[2]; } else { - p = &core_pattern[1]; + p = &pattern[1]; } / The path obviously cannot exceed UNIX_PATH_MAX. / @@ -1717,7 +1730,7 @@ static inline bool check_coredump_socket(void) return false; / Must not contain ".." in the path. / - if (name_contains_dotdot(core_pattern)) + if (name_contains_dotdot(pattern)) return false; return true; @@ -1726,27 +1739,34 @@ static inline bool check_coredump_socket(void) static int proc_dostring_coredump(const struct ctl_table table, int write, void buffer, size_t lenp, loff_t ppos) { + char pattern[CORENAME_MAX_SIZE]; + const struct ctl_table tmp = { + .procname = table->procname, + .data = pattern, + .maxlen = sizeof(pattern), + }; + bool changed = false; int error; - ssize_t retval; - char old_core_pattern[CORENAME_MAX_SIZE]; - - if (!write) - return proc_dostring(table, write, buffer, lenp, ppos); - retval = strscpy(old_core_pattern, core_pattern, CORENAME_MAX_SIZE); + / Work on a copy, proc_dostring() appends at ppos. / + scoped_guard(spinlock, &core_pattern_lock) + strscpy(pattern, core_pattern); - error = proc_dostring(table, write, buffer, lenp, ppos); - if (error) + error = proc_dostring(&tmp, write, buffer, lenp, ppos); + if (error \|\| !write) return error; - if (!check_coredump_socket()) { - strscpy(core_pattern, old_core_pattern, retval + 1); + if (!check_coredump_socket(pattern)) return -EINVAL; - } - if (strncmp(old_core_pattern, core_pattern, CORENAME_MAX_SIZE)) + /* Publish the validated pattern whole. / + scoped_guard(spinlock, &core_pattern_lock) { + changed = strncmp(pattern, core_pattern, CORENAME_MAX_SIZE); + strscpy(core_pattern, pattern); + } + if (changed) validate_coredump_safety(); - return error; + return 0; } static const unsigned int core_file_note_size_min = CORE_FILE_NOTE_SIZE_DEFAULT; diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index 70067ccfe2ba4..3a7ff3416e572 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -386,6 +386,11 @@ static inline int task_sigpending(struct task_struct p) return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING)); } +static inline int __fatal_signal_pending(struct task_struct p) +{ + return unlikely(sigismember(&p->pending.signal, SIGKILL)); +} + static inline int signal_pending(struct task_struct p) { /* @@ -395,12 +400,12 @@ static inline int signal_pending(struct task_struct p) / if (unlikely(test_tsk_thread_flag(p, TIF_NOTIFY_SIGNAL))) return 1; - return task_sigpending(p); -} - -static inline int __fatal_signal_pending(struct task_struct p) -{ - return unlikely(sigismember(&p->pending.signal, SIGKILL)); + if (!task_sigpending(p)) + return 0; + / A coredumping task only stops for SIGKILL, see dump_interrupted(). / + if (unlikely(READ_ONCE(p->flags) & PF_DUMPCORE)) + return __fatal_signal_pending(p); + return 1; } static inline int fatal_signal_pending(struct task_struct p) diff --git a/io_uring/io-wq.c b/io_uring/io-wq.c index 2ca223e47d41f..2a980e86dd940 100644 --- a/io_uring/io-wq.c +++ b/io_uring/io-wq.c @@ -1324,6 +1324,8 @@ static bool io_task_work_match(struct callback_head cb, void data) void io_wq_exit_start(struct io_wq wq) { set_bit(IO_WQ_BIT_EXIT, &wq->state); + / Pairs with task_work_add() in io_queue_worker_create(). / + smp_mb__after_atomic(); } static void io_wq_cancel_tw_create(struct io_wq wq) diff --git a/kernel/fork.c b/kernel/fork.c index 10be4a0ecb3f1..bd97fc7b885b4 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -2491,8 +2491,8 @@ __latent_entropy struct task_struct copy_process( goto bad_fork_core_free; } - / Let kill terminate clone/fork in the middle / - if (fatal_signal_pending(current)) { + / Let kill or a coredump in progress terminate clone/fork */ + if (fatal_signal_pending(current) \|\| current->signal->core_state) { retval = -EINTR; goto bad_fork_core_free; }
3/2	2026/09/15 13:03	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 5305 output: 25 thoughts: 667 Thoughts: My Initial Assessment of the Patch Okay, here's what's running through my mind as I examine this patch. First, I need to get a clear picture of the changes, so I'm breaking down each file: * `fs/coredump.c`: Looks like we're tightening up coredump handling. The introduction of `core_pattern_lock` is immediately interesting – clearly, a synchronization issue was identified. I see the lock used in `coredump_parse()` when handling `core_pattern` and throughout. I also see specific fixes related to vhost workers and improved memory barrier handling with `guard(rcu)();`. Changing the socket pattern and locking adds a layer of security by making pattern checks and changes atomic under the lock. This is all about thread safety and ensuring the integrity of the core dump process, which is critical. * `include/linux/sched/signal.h`: This change to `signal_pending()` is crucial. It's now directly checking `PF_DUMPCORE`, and will return `__fatal_signal_pending(p);` if that flag is set. That's a direct link to the coredump process – it's how the kernel decides if a signal should trigger a core dump. * `io_uring/io-wq.c`: Adding `smp_mb__after_atomic();` in `io_wq_exit_start()` is a memory barrier. This hints at potential race conditions or synchronization issues in the io\_uring workqueue shutdown sequence. This needs careful scrutiny to ensure that data is properly flushed and visible to other CPUs. * `kernel/fork.c`: The update to `copy_process()` is important. We're now terminating `clone` and `fork` calls if `fatal_signal_pending()` is true or if `current->signal->core_state` is set. This means we are preventing processes from forking or cloning if a fatal signal is pending or if a core dump is in progress. This adds a critical safety check for core dump behavior. Now, let's bring in the core triage philosophy. The main question here is: Is it reachable? According to the documentation, this is a core kernel modification: coredump, fork, signal\_pending, io\_uring. And yes, absolutely. Everything listed is directly reachable from userspace via syscalls like `fork`, `clone`, `ioctl`, `io_uring_setup`, `kill`, writing to `/proc/sys/kernel/core_pattern`. This is all core system functionality. WorthFuzzing=true. I need to confirm all the `CONFIG` options that apply here, and then I need to carefully cross-reference the `FocusSymbols`. I'll have to delve into the source code of `fs/coredump.c`, in particular, to see how everything integrates.
4/2	2026/09/15 13:03	tool	grepper	0m Args: { "Expression": "COREDUMP", "PathPrefix": "fs/" } Results: { "Output": "fs/Kconfig.binfmt=171=config BINFMT_MISC_BPF\n--\nfs/Kconfig.binfmt-184-\nfs/Kconfig.binfmt:185:config COREDUMP\nfs/Kconfig.binfmt-186-\tbool \"Enable core dump support\" if EXPERT\n--\nfs/Makefile=46=obj-$(CONFIG_NFS_COMMON)\t+= nfs_common/\nfs/Makefile:47:obj-$(CONFIG_COREDUMP)\t\t+= coredump.o\nfs/Makefile-48-obj-$(CONFIG_SYSCTL)\t\t+= drop_caches.o sysctls.o\n--\nfs/binfmt_elf.c=96=static struct linux_binfmt elf_format = {\n--\nfs/binfmt_elf.c-98-\t.load_binary\t= load_elf_binary,\nfs/binfmt_elf.c:99:#ifdef CONFIG_COREDUMP\nfs/binfmt_elf.c-100-\t.core_dump\t= elf_core_dump,\n--\nfs/binfmt_elf.c=1990=static bool elf_core_dump(struct coredump_params cprm)\n--\nfs/binfmt_elf.c-2022-\nfs/binfmt_elf.c:2023:\tcprm-\u003estate \|= COREDUMP_STATE_STARTED;\nfs/binfmt_elf.c-2024-\n--\nfs/binfmt_elf_fdpic.c=1480=static bool elf_fdpic_core_dump(struct coredump_params cprm)\n--\nfs/binfmt_elf_fdpic.c-1538-\nfs/binfmt_elf_fdpic.c:1539:\tcprm-\u003estate \|= COREDUMP_STATE_STARTED;\nfs/binfmt_elf_fdpic.c-1540-\t/\n--\nfs/coredump.c=73=static bool dump_flush_skip(struct coredump_params cprm);\n--\nfs/coredump.c-82- /\nfs/coredump.c:83:#define COREDUMP_PIDFD_NUMBER 3\nfs/coredump.c-84-\n--\nfs/coredump.c=95=enum coredump_type_t {\nfs/coredump.c:96:\tCOREDUMP_FILE\t\t= 1,\nfs/coredump.c:97:\tCOREDUMP_PIPE\t\t= 2,\nfs/coredump.c:98:\tCOREDUMP_SOCK\t\t= 3,\nfs/coredump.c:99:\tCOREDUMP_SOCK_REQ\t= 4,\nfs/coredump.c-100-};\n--\nfs/coredump.c=242=static bool coredump_parse(struct core_name cn, struct coredump_params cprm,\n--\nfs/coredump.c-255-\nfs/coredump.c:256:\tcprm-\u003emask = COREDUMP_KERNEL;\nfs/coredump.c-257-\tif (core_pipe_limit)\nfs/coredump.c:258:\t\tcprm-\u003emask \|= COREDUMP_WAIT;\nfs/coredump.c-259-\tcn-\u003eused = 0;\n--\nfs/coredump.c-262-\tif (pat_ptr == '\|')\nfs/coredump.c:263:\t\tcn-\u003ecore_type = COREDUMP_PIPE;\nfs/coredump.c-264-\telse if (pat_ptr == '@')\nfs/coredump.c:265:\t\tcn-\u003ecore_type = COREDUMP_SOCK;\nfs/coredump.c-266-\telse\nfs/coredump.c:267:\t\tcn-\u003ecore_type = COREDUMP_FILE;\nfs/coredump.c-268-\tif (expand_corename(cn, core_name_size))\n--\nfs/coredump.c-272-\tswitch (cn-\u003ecore_type) {\nfs/coredump.c:273:\tcase COREDUMP_PIPE: {\nfs/coredump.c-274-\t\tint argvs = sizeof(core_pattern) / 2;\n--\nfs/coredump.c-283-\t}\nfs/coredump.c:284:\tcase COREDUMP_SOCK: {\nfs/coredump.c-285-\t\t/ skip the @ /\n--\nfs/coredump.c-293-\nfs/coredump.c:294:\t\t\tcn-\u003ecore_type = COREDUMP_SOCK_REQ;\nfs/coredump.c-295-\t\t}\n--\nfs/coredump.c-333-\t}\nfs/coredump.c:334:\tcase COREDUMP_FILE:\nfs/coredump.c-335-\t\tbreak;\n--\nfs/coredump.c-347-\t\t /\nfs/coredump.c:348:\t\tif (cn-\u003ecore_type == COREDUMP_PIPE) {\nfs/coredump.c-349-\t\t\tif (isspace(pat_ptr)) {\n--\nfs/coredump.c-452-\t\t\t\t /\nfs/coredump.c:453:\t\t\t\tif (cn-\u003ecore_type != COREDUMP_PIPE)\nfs/coredump.c-454-\t\t\t\t\tbreak;\n--\nfs/coredump.c-464-\t\t\t\tcprm-\u003epid = task_tgid(current);\nfs/coredump.c:465:\t\t\t\terr = cn_printf(cn, \"%d\", COREDUMP_PIDFD_NUMBER);\nfs/coredump.c-466-\t\t\t\tbreak;\n--\nfs/coredump.c-483-\t * the filename. Do not do this for piped commands. /\nfs/coredump.c:484:\tif (cn-\u003ecore_type == COREDUMP_FILE \u0026\u0026 !pid_in_pattern \u0026\u0026 core_uses_pid)\nfs/coredump.c-485-\t\treturn cn_printf(cn, \".%d\", task_tgid_vnr(current)) == 0;\n--\nfs/coredump.c=490=static int zap_process(struct signal_struct signal, int exit_code)\n--\nfs/coredump.c-500-\t\ttask_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);\nfs/coredump.c:501:\t\tif (t != current \u0026\u0026 !(t-\u003eflags \u0026 PF_POSTCOREDUMP)) {\nfs/coredump.c-502-\t\t\tsigaddset(\u0026t-\u003epending.signal, SIGKILL);\n--\nfs/coredump.c=600=static void coredump_finish(enum coredump_state state)\n--\nfs/coredump.c-605-\tspin_lock_irq(\u0026current-\u003esighand-\u003esiglock);\nfs/coredump.c:606:\tif ((state \u0026 COREDUMP_STATE_STARTED) \u0026\u0026 !__fatal_signal_pending(current))\nfs/coredump.c-607-\t\tcurrent-\u003esignal-\u003egroup_exit_code \|= 0x80;\n--\nfs/coredump.c=672=static int umh_coredump_setup(struct subprocess_info info, struct cred new)\n--\nfs/coredump.c-691-\t\t * table. So we should always be able to use\nfs/coredump.c:692:\t\t * COREDUMP_PIDFD_NUMBER as our file descriptor value.\nfs/coredump.c-693-\t\t /\nfs/coredump.c:694:\t\terr = replace_fd(COREDUMP_PIDFD_NUMBER, pidfs_file, 0);\nfs/coredump.c-695-\t\tif (err \u003c 0)\n--\nfs/coredump.c-715-\nfs/coredump.c:716:static_assert(sizeof(struct coredump_record_header) == COREDUMP_RECORD_HEADER_SIZE_VER0);\nfs/coredump.c-717-\n--\nfs/coredump.c-719-/ af_unix halves the send buffer to size a single skb. /\nfs/coredump.c:720:#define COREDUMP_SOCK_SNDBUF_MIN (3 PAGE_SIZE)\nfs/coredump.c-721-\nfs/coredump.c=722=static bool coredump_sock_connect(struct core_name cn, struct coredump_params cprm)\n--\nfs/coredump.c-748-\tsocket-\u003esk-\u003esk_sndbuf = max_t(int, socket-\u003esk-\u003esk_sndbuf,\nfs/coredump.c:749:\t\t\t\t COREDUMP_SOCK_SNDBUF_MIN);\nfs/coredump.c-750-\n--\nfs/coredump.c-771-\tretval = kernel_connect(socket, (struct sockaddr_unsized )(\u0026addr), addr_len,\nfs/coredump.c:772:\t\t\t\tO_NONBLOCK \| SOCK_COREDUMP);\nfs/coredump.c-773-\n--\nfs/coredump.c=803=static inline bool coredump_sock_send(struct file file, struct coredump_req req)\n--\nfs/coredump.c-812-\nfs/coredump.c:813:static_assert(sizeof(struct coredump_req) == COREDUMP_REQ_SIZE_VER1);\nfs/coredump.c:814:static_assert(sizeof(struct coredump_ack) == COREDUMP_ACK_SIZE_VER1);\nfs/coredump.c-815-static_assert(sizeof(enum coredump_mark) == sizeof(__u32));\n--\nfs/coredump.c-817-/ Every memory type this kernel knows. /\nfs/coredump.c:818:#define COREDUMP_MEMORY_ALL\t\t\t\t\t\t\\\nfs/coredump.c:819:\t(COREDUMP_MEMORY_ANON_PRIVATE \| COREDUMP_MEMORY_ANON_SHARED \|\t\\\nfs/coredump.c:820:\t COREDUMP_MEMORY_FILE_PRIVATE \| COREDUMP_MEMORY_FILE_SHARED \|\t\\\nfs/coredump.c:821:\t COREDUMP_MEMORY_ELF_HEADERS \|\t\t\t\t\t\\\nfs/coredump.c:822:\t COREDUMP_MEMORY_HUGETLB_PRIVATE \| COREDUMP_MEMORY_HUGETLB_SHARED \| \\\nfs/coredump.c:823:\t COREDUMP_MEMORY_DAX_PRIVATE \| COREDUMP_MEMORY_DAX_SHARED)\nfs/coredump.c-824-\nfs/coredump.c:825:#define COREDUMP_MEMORY_TYPE_BIT(mmf) BIT((mmf) - MMF_DUMP_FILTER_SHIFT)\nfs/coredump.c:826:static_assert(COREDUMP_MEMORY_ALL == (MMF_DUMP_FILTER_MASK \u003e\u003e MMF_DUMP_FILTER_SHIFT));\nfs/coredump.c:827:static_assert(COREDUMP_MEMORY_ANON_PRIVATE ==\nfs/coredump.c:828:\t COREDUMP_MEMORY_TYPE_BIT(MMF_DUMP_ANON_PRIVATE));\nfs/coredump.c:829:static_assert(COREDUMP_MEMORY_ANON_SHARED ==\nfs/coredump.c:830:\t COREDUMP_MEMORY_TYPE_BIT(MMF_DUMP_ANON_SHARED));\nfs/coredump.c:831:static_assert(COREDUMP_MEMORY_FILE_PRIVATE ==\nfs/coredump.c:832:\t COREDUMP_MEMORY_TYPE_BIT(MMF_DUMP_MAPPED_PRIVATE));\nfs/coredump.c:833:static_assert(COREDUMP_MEMORY_FILE_SHARED ==\nfs/coredump.c:834:\t COREDUMP_MEMORY_TYPE_BIT(MMF_DUMP_MAPPED_SHARED));\nfs/coredump.c:835:static_assert(COREDUMP_MEMORY_ELF_HEADERS ==\nfs/coredump.c:836:\t COREDUMP_MEMORY_TYPE_BIT(MMF_DUMP_ELF_HEADERS));\nfs/coredump.c:837:static_assert(COREDUMP_MEMORY_HUGETLB_PRIVATE ==\nfs/coredump.c:838:\t COREDUMP_MEMORY_TYPE_BIT(MMF_DUMP_HUGETLB_PRIVATE));\nfs/coredump.c:839:static_assert(COREDUMP_MEMORY_HUGETLB_SHARED ==\nfs/coredump.c:840:\t COREDUMP_MEMORY_TYPE_BIT(MMF_DUMP_HUGETLB_SHARED));\nfs/coredump.c:841:static_assert(COREDUMP_MEMORY_DAX_PRIVATE ==\nfs/coredump.c:842:\t COREDUMP_MEMORY_TYPE_BIT(MMF_DUMP_DAX_PRIVATE));\nfs/coredump.c:843:static_assert(COREDUMP_MEMORY_DAX_SHARED ==\nfs/coredump.c:844:\t COREDUMP_MEMORY_TYPE_BIT(MMF_DUMP_DAX_SHARED));\nfs/coredump.c-845-\n--\nfs/coredump.c=884=static bool coredump_sock_request(struct core_name cn, struct coredump_params cprm)\n--\nfs/coredump.c-887-\t\t.size\t\t\t= sizeof(struct coredump_req),\nfs/coredump.c:888:\t\t.mask\t\t\t= COREDUMP_KERNEL \| COREDUMP_USERSPACE \|\nfs/coredump.c:889:\t\t\t\t\t COREDUMP_REJECT \| COREDUMP_WAIT \|\nfs/coredump.c:890:\t\t\t\t\t COREDUMP_RECORDS \| COREDUMP_SPARSE \|\nfs/coredump.c:891:\t\t\t\t\t COREDUMP_MEMORY_TYPES \|\nfs/coredump.c:892:\t\t\t\t\t COREDUMP_CLOSE_FILES,\nfs/coredump.c-893-\t\t.size_ack\t\t= sizeof(struct coredump_ack),\nfs/coredump.c-894-\t\t.memory_types\t\t= cprm-\u003ememory_types,\nfs/coredump.c:895:\t\t.memory_types_mask\t= COREDUMP_MEMORY_ALL,\nfs/coredump.c-896-\t};\n--\nfs/coredump.c-899-\nfs/coredump.c:900:\tif (cn-\u003ecore_type != COREDUMP_SOCK_REQ)\nfs/coredump.c-901-\t\treturn true;\n--\nfs/coredump.c-913-\tusize = ack.size;\nfs/coredump.c:914:\tif (usize \u003c COREDUMP_ACK_SIZE_VER0) {\nfs/coredump.c:915:\t\tcoredump_sock_mark(cprm-\u003efile, COREDUMP_MARK_MINSIZE);\nfs/coredump.c-916-\t\treturn false;\n--\nfs/coredump.c-919-\tif (usize \u003e sizeof(ack)) {\nfs/coredump.c:920:\t\tcoredump_sock_mark(cprm-\u003efile, COREDUMP_MARK_MAXSIZE);\nfs/coredump.c-921-\t\treturn false;\n--\nfs/coredump.c-931-\tif (ack.mask \u0026 ~req.mask) {\nfs/coredump.c:932:\t\tcoredump_sock_mark(cprm-\u003efile, COREDUMP_MARK_UNSUPPORTED);\nfs/coredump.c-933-\t\treturn false;\n--\nfs/coredump.c-936-\t/ Refuse mutually exclusive options. /\nfs/coredump.c:937:\tif (hweight64(ack.mask \u0026 (COREDUMP_USERSPACE \| COREDUMP_KERNEL \|\nfs/coredump.c:938:\t\t\t\t COREDUMP_REJECT)) != 1) {\nfs/coredump.c:939:\t\tcoredump_sock_mark(cprm-\u003efile, COREDUMP_MARK_CONFLICTING);\nfs/coredump.c-940-\t\treturn false;\n--\nfs/coredump.c-943-\tif (ack.spare) {\nfs/coredump.c:944:\t\tcoredump_sock_mark(cprm-\u003efile, COREDUMP_MARK_UNSUPPORTED);\nfs/coredump.c-945-\t\treturn false;\n--\nfs/coredump.c-948-\t/ Records only describe a coredump the kernel writes. /\nfs/coredump.c:949:\tif ((ack.mask \u0026 COREDUMP_RECORDS) \u0026\u0026 !(ack.mask \u0026 COREDUMP_KERNEL)) {\nfs/coredump.c:950:\t\tcoredump_sock_mark(cprm-\u003efile, COREDUMP_MARK_CONFLICTING);\nfs/coredump.c-951-\t\treturn false;\n--\nfs/coredump.c-954-\t/ Zero records only exist inside a record stream. /\nfs/coredump.c:955:\tif ((ack.mask \u0026 COREDUMP_SPARSE) \u0026\u0026 !(ack.mask \u0026 COREDUMP_RECORDS)) {\nfs/coredump.c:956:\t\tcoredump_sock_mark(cprm-\u003efile, COREDUMP_MARK_CONFLICTING);\nfs/coredump.c-957-\t\treturn false;\n--\nfs/coredump.c-960-\t/ A rejected task exits right away and closes everything anyway. /\nfs/coredump.c:961:\tif ((ack.mask \u0026 COREDUMP_CLOSE_FILES) \u0026\u0026 (ack.mask \u0026 COREDUMP_REJECT)) {\nfs/coredump.c:962:\t\tcoredump_sock_mark(cprm-\u003efile, COREDUMP_MARK_CONFLICTING);\nfs/coredump.c-963-\t\treturn false;\n--\nfs/coredump.c-965-\nfs/coredump.c:966:\tif (ack.mask \u0026 COREDUMP_MEMORY_TYPES) {\nfs/coredump.c-967-\t\t/ The memory types need the whole field. /\nfs/coredump.c:968:\t\tif (usize \u003c COREDUMP_ACK_SIZE_VER1) {\nfs/coredump.c:969:\t\t\tcoredump_sock_mark(cprm-\u003efile, COREDUMP_MARK_MINSIZE);\nfs/coredump.c-970-\t\t\treturn false;\n--\nfs/coredump.c-973-\t\t/ The memory types only select what the kernel writes. /\nfs/coredump.c:974:\t\tif (!(ack.mask \u0026 COREDUMP_KERNEL)) {\nfs/coredump.c:975:\t\t\tcoredump_sock_mark(cprm-\u003efile, COREDUMP_MARK_CONFLICTING);\nfs/coredump.c-976-\t\t\treturn false;\n--\nfs/coredump.c-980-\t\tif (ack.memory_types \u0026 ~req.memory_types_mask) {\nfs/coredump.c:981:\t\t\tcoredump_sock_mark(cprm-\u003efile, COREDUMP_MARK_UNSUPPORTED);\nfs/coredump.c-982-\t\t\treturn false;\n--\nfs/coredump.c-985-\t\t/ Like @spare the field must be zero when it isn't used. /\nfs/coredump.c:986:\t\tcoredump_sock_mark(cprm-\u003efile, COREDUMP_MARK_UNSUPPORTED);\nfs/coredump.c-987-\t\treturn false;\n--\nfs/coredump.c-990-\t/ Record header scratch; a bvec can't point at the stack. /\nfs/coredump.c:991:\tif (ack.mask \u0026 COREDUMP_RECORDS) {\nfs/coredump.c-992-\t\tcprm-\u003erecord_hdr = kmalloc_obj(cprm-\u003erecord_hdr);\n--\nfs/coredump.c-997-\t/* The server's selection replaces the task's entirely. /\nfs/coredump.c:998:\tif (ack.mask \u0026 COREDUMP_MEMORY_TYPES)\nfs/coredump.c-999-\t\tcprm-\u003ememory_types = ack.memory_types;\n--\nfs/coredump.c-1001-\tcprm-\u003emask = ack.mask;\nfs/coredump.c:1002:\treturn coredump_sock_mark(cprm-\u003efile, COREDUMP_MARK_REQACK);\nfs/coredump.c-1003-}\n--\nfs/coredump.c=1182=static bool coredump_write(struct coredump_params cprm,\n--\nfs/coredump.c-1185-\tif (dump_interrupted()) {\nfs/coredump.c:1186:\t\tcprm-\u003estate \|= COREDUMP_STATE_TRUNCATED;\nfs/coredump.c-1187-\t\treturn true;\n--\nfs/coredump.c-1190-\tif (!dump_vma_snapshot(cprm)) {\nfs/coredump.c:1191:\t\tcprm-\u003estate \|= COREDUMP_STATE_TRUNCATED;\nfs/coredump.c-1192-\t\treturn false;\n--\nfs/coredump.c-1196-\tif (!binfmt-\u003ecore_dump(cprm))\nfs/coredump.c:1197:\t\tcprm-\u003estate \|= COREDUMP_STATE_TRUNCATED;\nfs/coredump.c-1198-\t/\n--\nfs/coredump.c-1213-\t\tif (!flushed)\nfs/coredump.c:1214:\t\t\tcprm-\u003estate \|= COREDUMP_STATE_TRUNCATED;\nfs/coredump.c-1215-\t}\n--\nfs/coredump.c=1222=static void coredump_cleanup(struct core_name cn, struct coredump_params cprm)\n--\nfs/coredump.c-1226-\tif (cn-\u003ecore_pipe_limit) {\nfs/coredump.c:1227:\t\tVFS_WARN_ON_ONCE(cn-\u003ecore_type != COREDUMP_PIPE);\nfs/coredump.c-1228-\t\tatomic_dec(\u0026core_pipe_count);\n--\nfs/coredump.c=1247=static void do_coredump(struct core_name cn, struct coredump_params cprm,\n--\nfs/coredump.c-1257-\tswitch (cn-\u003ecore_type) {\nfs/coredump.c:1258:\tcase COREDUMP_FILE:\nfs/coredump.c-1259-\t\tif (!coredump_file(cn, cprm, binfmt))\n--\nfs/coredump.c-1261-\t\tbreak;\nfs/coredump.c:1262:\tcase COREDUMP_PIPE:\nfs/coredump.c-1263-\t\tif (!coredump_pipe(cn, cprm, argv, argc))\n--\nfs/coredump.c-1265-\t\tbreak;\nfs/coredump.c:1266:\tcase COREDUMP_SOCK_REQ:\nfs/coredump.c-1267-\t\tfallthrough;\nfs/coredump.c:1268:\tcase COREDUMP_SOCK:\nfs/coredump.c-1269-\t\tif (!coredump_socket(cn, cprm))\n--\nfs/coredump.c-1277-\t/ Don't even generate the coredump. /\nfs/coredump.c:1278:\tif (cprm-\u003emask \u0026 COREDUMP_REJECT)\nfs/coredump.c-1279-\t\treturn;\nfs/coredump.c-1280-\nfs/coredump.c:1281:\tif ((cprm-\u003emask \u0026 COREDUMP_CLOSE_FILES) \u0026\u0026\nfs/coredump.c-1282-\t !coredump_close_files(current-\u003esignal-\u003ecore_state))\n--\nfs/coredump.c-1284-\nfs/coredump.c:1285:\tif ((cprm-\u003emask \u0026 COREDUMP_KERNEL) \u0026\u0026 !coredump_write(cprm, binfmt))\nfs/coredump.c-1286-\t\treturn;\n--\nfs/coredump.c-1290-\t/ Let the parent know that a coredump was generated. /\nfs/coredump.c:1291:\tif (cprm-\u003emask \u0026 COREDUMP_USERSPACE)\nfs/coredump.c:1292:\t\tcprm-\u003estate \|= COREDUMP_STATE_STARTED;\nfs/coredump.c-1293-\n--\nfs/coredump.c-1298-\t /\nfs/coredump.c:1299:\tif (cprm-\u003emask \u0026 COREDUMP_WAIT) {\nfs/coredump.c-1300-\t\tswitch (cn-\u003ecore_type) {\nfs/coredump.c:1301:\t\tcase COREDUMP_PIPE:\nfs/coredump.c-1302-\t\t\twait_for_dump_helpers(cprm-\u003efile);\nfs/coredump.c-1303-\t\t\tbreak;\nfs/coredump.c:1304:\t\tcase COREDUMP_SOCK_REQ:\nfs/coredump.c-1305-\t\t\tfallthrough;\nfs/coredump.c:1306:\t\tcase COREDUMP_SOCK:\nfs/coredump.c-1307-\t\t\tcoredump_sock_wait(cprm-\u003efile);\n--\nfs/coredump.c-1314-\nfs/coredump.c:1315:#define COREDUMP_TASK_MEMORY_TYPES(mm) \\\nfs/coredump.c-1316-\t((__mm_flags_get_word((mm)) \u0026 MMF_DUMP_FILTER_MASK) \u003e\u003e \\\n--\nfs/coredump.c=1319=void vfs_coredump(const kernel_siginfo_t siginfo)\n--\nfs/coredump.c-1330-\t\t/ Snapshot the memory types (unlocked) and dumpable for the dump. /\nfs/coredump.c:1331:\t\t.memory_types = COREDUMP_TASK_MEMORY_TYPES(mm),\nfs/coredump.c-1332-\t\t.dumpable = task_exec_state_get_dumpable(current),\n--\nfs/coredump.c=1368=static bool dump_records(const struct coredump_params cprm)\nfs/coredump.c-1369-{\nfs/coredump.c:1370:\treturn cprm-\u003emask \u0026 COREDUMP_RECORDS;\nfs/coredump.c-1371-}\n--\nfs/coredump.c=1373=static bool dump_sparse(const struct coredump_params cprm)\nfs/coredump.c-1374-{\nfs/coredump.c:1375:\treturn cprm-\u003emask \u0026 COREDUMP_SPARSE;\nfs/coredump.c-1376-}\n--\nfs/coredump.c=1417=static bool dump_emit_chunk(struct coredump_params cprm, const void addr,\n--\nfs/coredump.c-1427-\nfs/coredump.c:1428:\thdrlen = dump_record_init(cprm, COREDUMP_RECORD_DATA, 0, nr);\nfs/coredump.c-1429-\tif (hdrlen) {\n--\nfs/coredump.c=1481=static void dump_end_record(struct coredump_params cprm)\nfs/coredump.c-1482-{\nfs/coredump.c:1483:\tif (cprm-\u003estate \u0026 COREDUMP_STATE_TRUNCATED)\nfs/coredump.c-1484-\t\treturn;\nfs/coredump.c-1485-\nfs/coredump.c:1486:\tdump_emit_record(cprm, COREDUMP_RECORD_END, 0, 0);\nfs/coredump.c-1487-}\n--\nfs/coredump.c=1489=static bool __dump_skip(struct coredump_params cprm, size_t nr)\n--\nfs/coredump.c-1497-\t\t\treturn false;\nfs/coredump.c:1498:\t\treturn dump_emit_record(cprm, COREDUMP_RECORD_ZERO, 0, nr);\nfs/coredump.c-1499-\t}\n--\nfs/coredump.c=1554=static bool dump_emit_page(struct coredump_params cprm, struct page page)\n--\nfs/coredump.c-1571-\t/ Hand the record header to the same write as the page it describes. /\nfs/coredump.c:1572:\thdrlen = dump_record_init(cprm, COREDUMP_RECORD_DATA, 0, PAGE_SIZE);\nfs/coredump.c-1573-\tif (hdrlen)\n--\nfs/coredump.c=1848=static bool always_dump_vma(struct vm_area_struct vma)\n--\nfs/coredump.c-1871-#define DUMP_SIZE_MAYBE_ELFHDR_PLACEHOLDER 1\nfs/coredump.c:1872:#define COREDUMP_MEMORY_TYPE_INCLUDE(types, type) \\\nfs/coredump.c:1873:\t((types) \u0026 COREDUMP_MEMORY_##type)\nfs/coredump.c-1874-\n--\nfs/coredump.c=1878=static unsigned long vma_dump_size(struct vm_area_struct vma,\n--\nfs/coredump.c-1890-\t\tif ((vma-\u003evm_flags \u0026 VM_SHARED) \u0026\u0026\nfs/coredump.c:1891:\t\t COREDUMP_MEMORY_TYPE_INCLUDE(memory_types, DAX_SHARED))\nfs/coredump.c-1892-\t\t\tgoto whole;\nfs/coredump.c-1893-\t\tif (!(vma-\u003evm_flags \u0026 VM_SHARED) \u0026\u0026\nfs/coredump.c:1894:\t\t COREDUMP_MEMORY_TYPE_INCLUDE(memory_types, DAX_PRIVATE))\nfs/coredump.c-1895-\t\t\tgoto whole;\n--\nfs/coredump.c-1901-\t\tif ((vma-\u003evm_flags \u0026 VM_SHARED) \u0026\u0026\nfs/coredump.c:1902:\t\t COREDUMP_MEMORY_TYPE_INCLUDE(memory_types, HUGETLB_SHARED))\nfs/coredump.c-1903-\t\t\tgoto whole;\nfs/coredump.c-1904-\t\tif (!(vma-\u003evm_flags \u0026 VM_SHARED) \u0026\u0026\nfs/coredump.c:1905:\t\t COREDUMP_MEMORY_TYPE_INCLUDE(memory_types, HUGETLB_PRIVATE))\nfs/coredump.c-1906-\t\t\tgoto whole;\n--\nfs/coredump.c-1916-\t\tif (file_inode(vma-\u003evm_file)-\u003ei_nlink == 0 ?\nfs/coredump.c:1917:\t\t\t COREDUMP_MEMORY_TYPE_INCLUDE(memory_types, ANON_SHARED) :\nfs/coredump.c:1918:\t\t\t COREDUMP_MEMORY_TYPE_INCLUDE(memory_types, FILE_SHARED))\nfs/coredump.c-1919-\t\t\tgoto whole;\n--\nfs/coredump.c-1924-\tif ((!IS_ENABLED(CONFIG_MMU) \|\| vma-\u003eanon_vma) \u0026\u0026\nfs/coredump.c:1925:\t COREDUMP_MEMORY_TYPE_INCLUDE(memory_types, ANON_PRIVATE))\nfs/coredump.c-1926-\t\tgoto whole;\n--\nfs/coredump.c-1929-\nfs/coredump.c:1930:\tif (COREDUMP_MEMORY_TYPE_INCLUDE(memory_types, FILE_PRIVATE))\nfs/coredump.c-1931-\t\tgoto whole;\n--\nfs/coredump.c-1936-\t /\nfs/coredump.c:1937:\tif (COREDUMP_MEMORY_TYPE_INCLUDE(memory_types, ELF_HEADERS) \u0026\u0026\nfs/coredump.c-1938-\t vma-\u003evm_pgoff == 0 \u0026\u0026 (vma-\u003evm_flags \u0026 VM_READ)) {\n--\nfs/pidfs.c=49=enum pidfs_attr_mask_bits {\nfs/pidfs.c-50-\tPIDFS_ATTR_BIT_EXIT\t= 0,\nfs/pidfs.c:51:\tPIDFS_ATTR_BIT_COREDUMP\t= 1,\nfs/pidfs.c-52-};\n--\nfs/pidfs.c=339=static __u32 pidfs_coredump_mask(enum task_dumpable dumpable)\n--\nfs/pidfs.c-342-\tcase TASK_DUMPABLE_OWNER:\nfs/pidfs.c:343:\t\treturn PIDFD_COREDUMP_USER;\nfs/pidfs.c-344-\tcase TASK_DUMPABLE_ROOT:\nfs/pidfs.c:345:\t\treturn PIDFD_COREDUMP_ROOT;\nfs/pidfs.c-346-\tcase TASK_DUMPABLE_OFF:\nfs/pidfs.c:347:\t\treturn PIDFD_COREDUMP_SKIP;\nfs/pidfs.c-348-\tdefault:\n--\nfs/pidfs.c-359-\t\t\t PIDFD_INFO_EXIT \| \\\nfs/pidfs.c:360:\t\t\t PIDFD_INFO_COREDUMP \| \\\nfs/pidfs.c-361-\t\t\t PIDFD_INFO_SUPPORTED_MASK \| \\\nfs/pidfs.c:362:\t\t\t PIDFD_INFO_COREDUMP_SIGNAL \| \\\nfs/pidfs.c:363:\t\t\t PIDFD_INFO_COREDUMP_CODE)\nfs/pidfs.c-364-\nfs/pidfs.c=365=static long pidfd_info(struct file file, unsigned int cmd, unsigned long arg)\n--\nfs/pidfs.c-406-\nfs/pidfs.c:407:\tif (mask \u0026 PIDFD_INFO_COREDUMP) {\nfs/pidfs.c:408:\t\tif (test_bit(PIDFS_ATTR_BIT_COREDUMP, \u0026attr-\u003eattr_mask)) {\nfs/pidfs.c-409-\t\t\tsmp_rmb();\nfs/pidfs.c:410:\t\t\tkinfo.mask \|= PIDFD_INFO_COREDUMP \| PIDFD_INFO_COREDUMP_SIGNAL \| PIDFD_INFO_COREDUMP_CODE;\nfs/pidfs.c-411-\t\t\tkinfo.coredump_mask = attr-\u003ecoredump_mask;\n--\nfs/pidfs.c-432-\nfs/pidfs.c:433:\tif ((mask \u0026 PIDFD_INFO_COREDUMP) \u0026\u0026 !kinfo.coredump_mask) {\nfs/pidfs.c-434-\t\tkinfo.coredump_mask = pidfs_coredump_mask(task_exec_state_get_dumpable(task));\nfs/pidfs.c:435:\t\tkinfo.mask \|= PIDFD_INFO_COREDUMP;\nfs/pidfs.c-436-\t\t/ No coredump actually took place, so no coredump signal. /\n--\nfs/pidfs.c=749=void pidfs_exit(struct task_struct tsk)\n--\nfs/pidfs.c-794-\nfs/pidfs.c:795:#ifdef CONFIG_COREDUMP\nfs/pidfs.c-796-void pidfs_coredump(const struct coredump_params cprm)\n--\nfs/pidfs.c-807-\tattr-\u003ecoredump_mask = pidfs_coredump_mask(cprm-\u003edumpable) \|\nfs/pidfs.c:808:\t\t\t PIDFD_COREDUMPED;\nfs/pidfs.c-809-\t/ If coredumping is set to skip we should never end up here. /\nfs/pidfs.c:810:\tVFS_WARN_ON_ONCE(attr-\u003ecoredump_mask \u0026 PIDFD_COREDUMP_SKIP);\nfs/pidfs.c-811-\t/ Expose the signal number and code that caused the coredump. /\n--\nfs/pidfs.c-814-\tsmp_wmb();\nfs/pidfs.c:815:\tset_bit(PIDFS_ATTR_BIT_COREDUMP, \u0026attr-\u003eattr_mask);\nfs/pidfs.c-816-}\n--\nfs/proc/array.c=466=static int do_task_stat(struct seq_file m, struct pid_namespace ns,\n--\nfs/proc/array.c-505-\t\t /\nfs/proc/array.c:506:\t\tif (permitted \u0026\u0026 (task-\u003eflags \u0026 (PF_EXITING\|PF_DUMPCORE\|PF_POSTCOREDUMP))) {\nfs/proc/array.c-507-\t\t\tif (try_get_task_stack(task)) {\n" }
5/2	2026/09/15 13:03	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 15980 output: 34 thoughts: 19 Thoughts: Here's a summary of my thought process, as requested: Diving into `fork.c` - Potential Issue Location Okay, so I need to get to the bottom of this. My gut feeling tells me there's something amiss with how the child process is being created and initialized, especially if we're seeing unexpected behavior related to resource allocation or process state. Let's start by looking at `kernel/fork.c`, that's the obvious place to begin, it's where the `fork()` system call implementation lives. Line 2491, huh? That's a specific line. I'll bet there's something interesting happening around there. This might be where some crucial data structure initialization occurs, or maybe even a critical memory allocation is made. Maybe some flag is being set or not set correctly. Let's see if that's the root cause or just another data point. Gotta dive in there and see what the code is really doing. I'm hoping I can spot a logic flaw or a subtle bug, something that could be causing this unpredictable behavior. Time to get my hands dirty.
6/2	2026/09/15 13:03	tool	read-file	0m Args: { "File": "kernel/fork.c", "FirstLine": 2485, "LineCount": 20 } Results: { "Contents": "2485:\t\t * If zap_pid_ns_processes() was called after alloc_pid(), the new\n2486:\t\t * child missed SIGKILL. If current is not in the same namespace,\n2487:\t\t * we can't rely on fatal_signal_pending() below.\n2488:\t\t /\n2489:\t\tif (unlikely(!(ns_of_pid(pid)-\u003epid_allocated \u0026 PIDNS_ADDING))) {\n2490:\t\t\tretval = -ENOMEM;\n2491:\t\t\tgoto bad_fork_core_free;\n2492:\t\t}\n2493:\t\n2494:\t\t/ Let kill or a coredump in progress terminate clone/fork /\n2495:\t\tif (fatal_signal_pending(current) \|\| current-\u003esignal-\u003ecore_state) {\n2496:\t\t\tretval = -EINTR;\n2497:\t\t\tgoto bad_fork_core_free;\n2498:\t\t}\n2499:\t\n2500:\t\t/ No more failure paths after this point. /\n2501:\t\n2502:\t\t/\n2503:\t\t * Copy seccomp details explicitly here, in case they were changed\n2504:\t\t * before holding sighand lock.\n" }
7/2	2026/09/15 13:03	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 16600 output: 38 thoughts: 23 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: Diving into io_uring's Workqueue Implementation Okay, time to dig into the `io_uring/io-wq.c` file. Specifically, I need to zero in on the workqueue implementation, and line 1324 seems like a good starting point. I suspect that area deals with [insert your hypothesis, based on your expertise]. I'm looking for the mechanisms behind how I/O operations are offloaded and managed within the kernel's workqueue context. I want to understand the interaction between the submission queue, completion queue, and the worker threads. I'm especially interested in how the completion notifications are handled and whether there's any potential for [mention a specific concern, e.g., lock contention, queue starvation, performance bottlenecks] in this particular section of the code. Let's see what line 1324 reveals... I'll be looking closely at the data structures and control flow around that point.
8/2	2026/09/15 13:03	tool	read-file	0m Args: { "File": "io_uring/io-wq.c", "FirstLine": 1320, "LineCount": 20 } Results: { "Contents": "1320:\t\tworker = container_of(cb, struct io_worker, create_work);\n1321:\t\treturn worker-\u003ewq == data;\n1322:\t}\n1323:\t\n1324:\tvoid io_wq_exit_start(struct io_wq wq)\n1325:\t{\n1326:\t\tset_bit(IO_WQ_BIT_EXIT, \u0026wq-\u003estate);\n1327:\t\t/ Pairs with task_work_add() in io_queue_worker_create(). /\n1328:\t\tsmp_mb__after_atomic();\n1329:\t}\n1330:\t\n1331:\tstatic void io_wq_cancel_tw_create(struct io_wq wq)\n1332:\t{\n1333:\t\tstruct callback_head cb;\n1334:\t\n1335:\t\twhile ((cb = task_work_cancel_match(wq-\u003etask, io_task_work_match, wq)) != NULL) {\n1336:\t\t\tstruct io_worker worker;\n1337:\t\n1338:\t\t\tworker = container_of(cb, struct io_worker, create_work);\n1339:\t\t\tio_worker_cancel_cb(worker);\n" }
9/2	2026/09/15 13:03	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 17213 output: 25 thoughts: 37 Thoughts: Okay, here's my interpretation of those thoughts, framed as my own: Analyzing Recent Git Changes Right, let's dive into this set of modifications. Before I start dissecting the code itself, I need to understand the why behind this particular commit. My first instinct is to check the Git history – I need context. I'll take a look at the commit log to see what motivated this batch of changes. Specifically, I'll use `git log -1` to zero in on the most recent commit and read that message. The commit message usually provides the critical information I need to understand the intent and reasoning behind the code. Knowing the purpose will guide my review and help me assess whether the implementation aligns with the original goal.
10/2	2026/09/15 13:04	tool	grepper	0m Error: no matches Args: { "Expression": ".", "PathPrefix": ".git/config" } Results:* { "error": "no matches" }
11/2	2026/09/15 13:04	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 17446 output: 34 thoughts: 29 Thoughts: Okay, here's my interpretation of those thoughts, tailored for an expert audience, presented in the first person: Navigating the Grepper Limitation and Core Dump Implementation Right, so Grepper is giving me grief with this `.git` limitation. I need to get a handle on the changes around core dumps, and it's looking like `fs/coredump.c` is the place to start digging. Grepper's limitation is a hindrance, of course, but it forces me to be methodical. It's time to thoroughly inspect that file, focusing on the context around any recent modifications to the relevant functions. I need to reconstruct the full picture of the implementation, not just isolated snippets. Looking at the whole function, it should be possible to understand what caused this issue.
12/2	2026/09/15 13:04	tool	read-file	0m Args: { "File": "fs/coredump.c", "FirstLine": 240, "LineCount": 40 } Results: { "Contents": " 240:\t * bytes plus one byte for the zero terminator.\n 241:\t /\n 242:\tstatic bool coredump_parse(struct core_name cn, struct coredump_params cprm,\n 243:\t\t\t\t size_t argv, int argc)\n 244:\t{\n 245:\t\tconst struct cred cred = current_cred();\n 246:\t\tchar pattern[CORENAME_MAX_SIZE];\n 247:\t\tconst char pat_ptr = pattern;\n 248:\t\tbool was_space = false;\n 249:\t\tint pid_in_pattern = 0;\n 250:\t\tint err = 0;\n 251:\t\n 252:\t\t/* The sysctl handler may be publishing a new pattern. /\n 253:\t\tscoped_guard(spinlock, \u0026core_pattern_lock)\n 254:\t\t\tstrscpy(pattern, core_pattern);\n 255:\t\n 256:\t\tcprm-\u003emask = COREDUMP_KERNEL;\n 257:\t\tif (core_pipe_limit)\n 258:\t\t\tcprm-\u003emask \|= COREDUMP_WAIT;\n 259:\t\tcn-\u003eused = 0;\n 260:\t\tcn-\u003ecorename = NULL;\n 261:\t\tcn-\u003ecore_pipe_limit = 0;\n 262:\t\tif (pat_ptr == '\|')\n 263:\t\t\tcn-\u003ecore_type = COREDUMP_PIPE;\n 264:\t\telse if (pat_ptr == '@')\n 265:\t\t\tcn-\u003ecore_type = COREDUMP_SOCK;\n 266:\t\telse\n 267:\t\t\tcn-\u003ecore_type = COREDUMP_FILE;\n 268:\t\tif (expand_corename(cn, core_name_size))\n 269:\t\t\treturn false;\n 270:\t\tcn-\u003ecorename[0] = '\\0';\n 271:\t\n 272:\t\tswitch (cn-\u003ecore_type) {\n 273:\t\tcase COREDUMP_PIPE: {\n 274:\t\t\tint argvs = sizeof(core_pattern) / 2;\n 275:\t\t\t(argv) = kmalloc_objs(*argv, argvs);\n 276:\t\t\tif (!(argv))\n 277:\t\t\t\treturn false;\n 278:\t\t\t(argv)[(argc)++] = 0;\n 279:\t\t\t++pat_ptr;\n" }
13/2	2026/09/15 13:04	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 18308 output: 34 thoughts: 12 Thoughts: Here's my attempt at summarizing the thought process, tailored for an expert audience: Analyzing `coredump_close_files` Okay, let's dive into this `coredump_close_files` function. I need to understand its exact purpose and behavior. My first thought is: what are the potential pitfalls? Are we dealing with file descriptors, sockets, shared memory, or a combination? The function's name implies it's related to closing files associated with core dumps, but the devil is always in the details. I'll need to consider: * Concurrency: Is this function thread-safe? Does it need to be protected by a mutex, or are there inherent race conditions it needs to handle? Context matters. Is it called in a signal handler, a different thread, or from within a core dump processing library? * Error Handling: What kind of error codes could it return, and what are the implications of those errors? Does it log these errors, and if so, where and how? Is there a cascading failure scenario if a file cannot be closed (e.g., if a file is on a non-responsive NFS share)? How robust is the error handling? * Resource Management: Are there any resources (other than file descriptors) that are cleaned up in this function, such as locks, memory allocated for file metadata, or other operating system resources? How carefully are they released? * Security: Could this function be exploited to trigger a denial-of-service or even a more serious vulnerability? Are there any potential vulnerabilities to a symlink attack here? * Context: What is the calling environment for this function? Are there any special considerations for different operating systems or architectures? I'll be looking specifically for any non-obvious behavior, corner cases, or potential for memory leaks or resource exhaustion. I need to verify that it's handling all of these conditions correctly. I'll probably look to see if this function is only called from one location, or if it is a general function. If it is only called from one location, I will probably see how the code handles different failure conditions of `coredump_close_files`.
14/2	2026/09/15 13:04	tool	read-file	0m Args: { "File": "fs/coredump.c", "FirstLine": 580, "LineCount": 40 } Results: { "Contents": " 580:\t\t\tatomic_inc(\u0026files-\u003ecount);\n 581:\t\t\t/* Pairs with the acquire in coredump_task_exit(). /\n 582:\t\t\tsmp_store_release(\u0026ct-\u003efiles, files);\n 583:\t\t\twake_up_process(ct-\u003etask);\n 584:\t\t}\n 585:\t\n 586:\t\t/ Use the dumper's real creds not the overridden ones. /\n 587:\t\tscoped_with_creds(current_real_cred()) {\n 588:\t\t\tio_uring_task_cancel();\n 589:\t\t\t/ The dumper itself may be a vhost worker without a table. /\n 590:\t\t\tif (current-\u003efiles)\n 591:\t\t\t\tswitch_files_struct(current, files);\n 592:\t\t\telse\n 593:\t\t\t\tput_files_struct(files);\n 594:\t\t}\n 595:\t\n 596:\t\tcoredump_wait_inactive(core_state);\n 597:\t\treturn true;\n 598:\t}\n 599:\t\n 600:\tstatic void coredump_finish(enum coredump_state state)\n 601:\t{\n 602:\t\tstruct core_thread curr, next;\n 603:\t\tstruct task_struct task;\n 604:\t\n 605:\t\tspin_lock_irq(\u0026current-\u003esighand-\u003esiglock);\n 606:\t\tif ((state \u0026 COREDUMP_STATE_STARTED) \u0026\u0026 !__fatal_signal_pending(current))\n 607:\t\t\tcurrent-\u003esignal-\u003egroup_exit_code \|= 0x80;\n 608:\t\tnext = current-\u003esignal-\u003ecore_state-\u003etasks;\n 609:\t\tcurrent-\u003esignal-\u003ecore_state = NULL;\n 610:\t\tspin_unlock_irq(\u0026current-\u003esighand-\u003esiglock);\n 611:\t\n 612:\t\t/* A released thread may exit and be freed before it is woken. /\n 613:\t\tguard(rcu)();\n 614:\t\twhile ((curr = next) != NULL) {\n 615:\t\t\tnext = curr-\u003enext;\n 616:\t\t\ttask = curr-\u003etask;\n 617:\t\t\t/\n 618:\t\t\t * see coredump_task_exit(), curr-\u003etask must not see\n 619:\t\t\t * -\u003etask == NULL before we read -\u003enext.\n" }
15/2	2026/09/15 13:04	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 19448 output: 35 thoughts: 16 Thoughts: Okay, here's my interpretation of that thought process, tailored for an expert audience, and presented as if it were my own internal monologue: Diving Deeper into `proc_dostring_coredump` Alright, so we're circling back, and I want to zero in on `proc_dostring_coredump`. It's a key function in this overall debugging process, right? I'm thinking, "Let's really understand this one". We've likely hit a snag or perhaps are working our way to another potential error. Given my familiarity with [insert your field here - e.g., kernel debugging, embedded systems, reverse engineering], I know this is where the meat of potentially core dump generation or analysis would likely occur. What are the potential issues we should focus on within this function? I'm looking at things like the data structures it's interacting with and the context in which it's being called. The question now is whether the core dump is being generated correctly, or if there's an error in writing to disk, or, even worse, if it's being triggered at the wrong time. This function has many layers, and many points to go wrong. Time to put my debugging hat on.
16/2	2026/09/15 13:04	tool	read-file	0m Args: { "File": "fs/coredump.c", "FirstLine": 1735, "LineCount": 45 } Results: { "Contents": "1735:\t\n1736:\t\treturn true;\n1737:\t}\n1738:\t\n1739:\tstatic int proc_dostring_coredump(const struct ctl_table table, int write,\n1740:\t\t\t void buffer, size_t lenp, loff_t ppos)\n1741:\t{\n1742:\t\tchar pattern[CORENAME_MAX_SIZE];\n1743:\t\tconst struct ctl_table tmp = {\n1744:\t\t\t.procname\t= table-\u003eprocname,\n1745:\t\t\t.data\t\t= pattern,\n1746:\t\t\t.maxlen\t\t= sizeof(pattern),\n1747:\t\t};\n1748:\t\tbool changed = false;\n1749:\t\tint error;\n1750:\t\n1751:\t\t/* Work on a copy, proc_dostring() appends at ppos. /\n1752:\t\tscoped_guard(spinlock, \u0026core_pattern_lock)\n1753:\t\t\tstrscpy(pattern, core_pattern);\n1754:\t\n1755:\t\terror = proc_dostring(\u0026tmp, write, buffer, lenp, ppos);\n1756:\t\tif (error \|\| !write)\n1757:\t\t\treturn error;\n1758:\t\n1759:\t\tif (!check_coredump_socket(pattern))\n1760:\t\t\treturn -EINVAL;\n1761:\t\n1762:\t\t/* Publish the validated pattern whole. */\n1763:\t\tscoped_guard(spinlock, \u0026core_pattern_lock) {\n1764:\t\t\tchanged = strncmp(pattern, core_pattern, CORENAME_MAX_SIZE);\n1765:\t\t\tstrscpy(core_pattern, pattern);\n1766:\t\t}\n1767:\t\tif (changed)\n1768:\t\t\tvalidate_coredump_safety();\n1769:\t\treturn 0;\n1770:\t}\n1771:\t\n1772:\tstatic const unsigned int core_file_note_size_min = CORE_FILE_NOTE_SIZE_DEFAULT;\n1773:\tstatic const unsigned int core_file_note_size_max = CORE_FILE_NOTE_SIZE_MAX;\n1774:\tstatic char core_modes[] = {\n1775:\t\t\"file\\npipe\"\n1776:\t#ifdef CONFIG_UNIX\n1777:\t\t\"\\nsocket\"\n1778:\t#endif\n1779:\t};\n" }
17/2	2026/09/15 13:04	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 20424 output: 37 thoughts: 16 Thoughts: Here's a summary of my thought process: Diving into Signal Handling in the Kernel Okay, time to dig deeper into how signals are managed within the Linux kernel. My current focus is on understanding the intricacies of signal handling, and naturally, the first place to go is `include/linux/sched/signal.h`. This header file is the definitive source for core signal-related data structures and definitions, it's where the magic starts. I'm anticipating that this will give me the building blocks and foundation I need to grasp the logic. I expect to find critical structures like `siginfo`, `sigpending`, and the definitions for signal masks and handlers themselves. Understanding these definitions is absolutely fundamental to understanding any kernel code related to signal delivery and processing. So, let's get into it.
18/2	2026/09/15 13:04	tool	read-file	0m Args: { "File": "include/linux/sched/signal.h", "FirstLine": 380, "LineCount": 40 } Results: { "Contents": " 380:\t\tset_tsk_thread_flag(current, TIF_SIGPENDING);\n 381:\t\treturn -ERESTARTNOINTR;\n 382:\t}\n 383:\t\n 384:\tstatic inline int task_sigpending(struct task_struct p)\n 385:\t{\n 386:\t\treturn unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING));\n 387:\t}\n 388:\t\n 389:\tstatic inline int __fatal_signal_pending(struct task_struct p)\n 390:\t{\n 391:\t\treturn unlikely(sigismember(\u0026p-\u003epending.signal, SIGKILL));\n 392:\t}\n 393:\t\n 394:\tstatic inline int signal_pending(struct task_struct p)\n 395:\t{\n 396:\t\t/\n 397:\t\t * TIF_NOTIFY_SIGNAL isn't really a signal, but it requires the same\n 398:\t\t * behavior in terms of ensuring that we break out of wait loops\n 399:\t\t * so that notify signal callbacks can be processed.\n 400:\t\t /\n 401:\t\tif (unlikely(test_tsk_thread_flag(p, TIF_NOTIFY_SIGNAL)))\n 402:\t\t\treturn 1;\n 403:\t\tif (!task_sigpending(p))\n 404:\t\t\treturn 0;\n 405:\t\t/ A coredumping task only stops for SIGKILL, see dump_interrupted(). /\n 406:\t\tif (unlikely(READ_ONCE(p-\u003eflags) \u0026 PF_DUMPCORE))\n 407:\t\t\treturn __fatal_signal_pending(p);\n 408:\t\treturn 1;\n 409:\t}\n 410:\t\n 411:\tstatic inline int fatal_signal_pending(struct task_struct p)\n 412:\t{\n 413:\t\treturn task_sigpending(p) \u0026\u0026 __fatal_signal_pending(p);\n 414:\t}\n 415:\t\n 416:\tstatic inline int signal_pending_state(unsigned int state, struct task_struct *p)\n 417:\t{\n 418:\t\tif (!(state \u0026 (TASK_INTERRUPTIBLE \| TASK_WAKEKILL)))\n 419:\t\t\treturn 0;\n" }
19/2	2026/09/15 13:04	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 21273 output: 19 thoughts: 1571 Thoughts: Core Dump Vulnerability Analysis for Fuzzing Alright, let's break this down. Seeing `signal_pending` and its interaction with `PF_DUMPCORE` immediately raises my eyebrows. This is a critical signal handling function, and `PF_DUMPCORE` ties directly into the core dump mechanism. The fact that `copy_process` in `kernel/fork.c` now explicitly checks for `current->signal->core_state` confirms my initial thought: we're dealing with a coredump and process forking/cloning interaction. This is a classic recipe for race conditions, and therefore, definitely worth fuzzing. My primary focus here is understanding what specific elements are added, and what elements are changed. Now, to determine the "FocusSymbols," I need to avoid listing ubiquitous functions that get called frequently, like `copy_process`. Including `copy_process` would be a disaster, classifying almost every test as "focused" and diluting the fuzzing effort. Let's look more closely at the functions in `fs/coredump.c`, and their interactions. - `coredump_parse` is a static function that handles coredump parsing and is called by `do_coredump` and `vfs_coredump`. - `coredump_close_files` and `coredump_finish` are also statically defined and called by `do_coredump`. - `check_coredump_socket` is static inline function. - `proc_dostring_coredump` is a proc/sysctl handler. - `vfs_coredump` is a direct entry point into the core dumping mechanism, and where many interesting points occur! - `do_coredump` calls these functions. So, `vfs_coredump` is a very interesting target, a feature specific entry point to core dumping that directly interacts with kernel signal handling, process lifecycle, and file system interactions. The proc entry also provides an interesting entrypoint, and could have interesting configuration capabilities. The other function is `io_wq_exit_start` in `io_uring/io-wq.c`, which is also worth noting as it's a non-static function. Now, considering the bug fix in `kernel/fork.c`, I'm looking for conditions where `current->signal->core_state` is set, such as `zap_process()`, `coredump_wait_inactive()`, and of course, `vfs_coredump()`. I'm going to look for configurations where `PF_DUMPCORE` is set and cleared, as this specifically affects tasks. The interaction between coredumps and forks/threads looks like the core focus for this fuzzing effort.
20/2	2026/09/15 13:04	tool	grepper	0m Args: { "Expression": "PF_DUMPCORE" } Results: { "Output": "fs/coredump.c=511=static int zap_threads(struct task_struct tsk,\n--\nfs/coredump.c-522-\t\tclear_tsk_thread_flag(tsk, TIF_SIGPENDING);\nfs/coredump.c:523:\t\ttsk-\u003eflags \|= PF_DUMPCORE;\nfs/coredump.c-524-\t\tatomic_set(\u0026core_state-\u003ethreads_remaining, nr);\n--\nfs/fs_struct.c=56=void chroot_fs_refs(const struct path old_root, const struct path new_root)\n--\nfs/fs_struct.c-63-\tfor_each_process_thread(g, p) {\nfs/fs_struct.c:64:\t\tif (p-\u003eflags \u0026 (PF_KTHREAD \| PF_EXITING \| PF_DUMPCORE))\nfs/fs_struct.c-65-\t\t\tcontinue;\n--\nfs/proc/array.c=466=static int do_task_stat(struct seq_file m, struct pid_namespace ns,\n--\nfs/proc/array.c-505-\t\t /\nfs/proc/array.c:506:\t\tif (permitted \u0026\u0026 (task-\u003eflags \u0026 (PF_EXITING\|PF_DUMPCORE\|PF_POSTCOREDUMP))) {\nfs/proc/array.c-507-\t\t\tif (try_get_task_stack(task)) {\n--\ninclude/linux/sched.h=1790=extern struct pid __rcu cad_pid;\n--\ninclude/linux/sched.h-1803-#define PF_SUPERPRIV\t\t0x00000100\t/ Used super-user privileges /\ninclude/linux/sched.h:1804:#define PF_DUMPCORE\t\t0x00000200\t/ Dumped core /\ninclude/linux/sched.h-1805-#define PF_SIGNALED\t\t0x00000400\t/ Killed by a signal /\n--\ninclude/linux/sched/signal.h=394=static inline int signal_pending(struct task_struct p)\n--\ninclude/linux/sched/signal.h-405-\t/* A coredumping task only stops for SIGKILL, see dump_interrupted(). /\ninclude/linux/sched/signal.h:406:\tif (unlikely(READ_ONCE(p-\u003eflags) \u0026 PF_DUMPCORE))\ninclude/linux/sched/signal.h-407-\t\treturn __fatal_signal_pending(p);\n--\nkernel/acct.c=557=void acct_collect(long exitcode, int group_dead)\n--\nkernel/acct.c-583-\t\tpacct-\u003eac_flag \|= ASU;\nkernel/acct.c:584:\tif (current-\u003eflags \u0026 PF_DUMPCORE)\nkernel/acct.c-585-\t\tpacct-\u003eac_flag \|= ACORE;\n--\nkernel/tsacct.c=20=void bacct_add_tsk(struct user_namespace user_ns,\n--\nkernel/tsacct.c-51-\t\tstats-\u003eac_flag \|= ASU;\nkernel/tsacct.c:52:\tif (tsk-\u003eflags \u0026 PF_DUMPCORE)\nkernel/tsacct.c-53-\t\tstats-\u003eac_flag \|= ACORE;\n--\nmm/page_alloc.c=4044=__alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,\n--\nmm/page_alloc.c-4081-\t/* Coredumps can quickly deplete all memory reserves /\nmm/page_alloc.c:4082:\tif (current-\u003eflags \u0026 PF_DUMPCORE)\nmm/page_alloc.c-4083-\t\tgoto out;\n--\nmm/userfaultfd.c=2838=vm_fault_t handle_userfault(struct vm_fault vmf, unsigned long reason)\n--\nmm/userfaultfd.c-2851-\t */\nmm/userfaultfd.c:2852:\tif (current-\u003eflags \u0026 (PF_EXITING\|PF_DUMPCORE))\nmm/userfaultfd.c-2853-\t\tgoto out;\n" }
21/2	2026/09/15 13:04	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 24506 output: 35 thoughts: 319 Thoughts: My Analysis of the Core Dump Implementation Okay, so I'm looking at this code and immediately I see `PF_DUMPCORE` is being set exclusively within `zap_threads` in `fs/coredump.c`. That's my first clue; it's a critical flag related to coredumping. `zap_threads`... I remember that, that gets called from `vfs_coredump()`. So everything here is centered around how a core dump is generated. Good start. Now, let's look at `fs/coredump.c` itself. I need to understand the key functions. Okay, here's what jumps out: 1. `proc_dostring_coredump`: the sysctl handler for managing the `core_pattern`. That's where you configure where and how the core files are named. 2. `coredump_parse`: It’s responsible for actually parsing the core pattern and setting up the parameters for the core dump process. That's a critical function for setting the core dump parameters. 3. `coredump_close_files`: This is about closing or switching files. It's obviously important for managing file handles during the dump. 4. `coredump_finish`: This one finishes the coredump and, crucially, wakes up any threads that might be waiting. 5. `vfs_coredump`: This is the entry point for the coredumping process itself when a signal triggers a core dump. This is probably the start of everything. 6. `do_coredump`: The core implementation, the actual work of generating the core dump. 7. `io_wq_exit_start`: This is interesting, it's related to the io_uring worker exit process, from `io_uring/io-wq.c`. This could impact any of the I/O related core dump options. Hmm, wait. What's required from a configuration perspective? I should check the Kconfig files. Okay, let's start with `fs/coredump.c` itself. It looks like `CONFIG_COREDUMP` is the key. And then, I need to check `fs/Kconfig.binfmt` to see if there is anything important there as well.
22/2	2026/09/15 13:04	tool	read-file	0m Args: { "File": "fs/Kconfig.binfmt", "FirstLine": 180, "LineCount": 20 } Results: { "Contents": " 180:\t\t interpreter to use per binary, e.g. relative to the location of\n 181:\t\t the binary itself.\n 182:\t\n 183:\t\t If you don't know what to answer at this point, say N.\n 184:\t\n 185:\tconfig COREDUMP\n 186:\t\tbool \"Enable core dump support\" if EXPERT\n 187:\t\tdefault y\n 188:\t\thelp\n 189:\t\t This option enables support for performing core dumps. You almost\n 190:\t\t certainly want to say Y here. Not necessary on systems that never\n 191:\t\t need debugging or only ever run flawless code.\n 192:\t\n 193:\tconfig EXEC_KUNIT_TEST\n 194:\t\tbool \"Build execve tests\" if !KUNIT_ALL_TESTS\n 195:\t\tdepends on KUNIT=y\n 196:\t\tdefault KUNIT_ALL_TESTS\n 197:\t\thelp\n 198:\t\t This builds the exec KUnit tests, which tests boundary conditions\n 199:\t\t of various aspects of the exec internals.\n" }
23/2	2026/09/15 13:04	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 25664 output: 29 thoughts: 13 Thoughts: Here's my take on the thought process, summarized as you requested: Diving into the `io-wq.c` Configuration Okay, time to get my hands dirty. I'm going to start by taking a close look at the `io-wq.c` configuration. I need to refresh my memory on the current setup and make sure I understand how it's interacting with the rest of the system. I'm expecting to find details on workqueue parameters, potentially some scheduling policies, and of course, the general architecture of how I/O operations are being handled. Specifically, I'm thinking about things like the number of worker threads, any affinity settings, and how the work is being distributed. I need to quickly grasp the current state before I can make any informed decisions about potential optimizations or modifications. I am assuming I will find things like: how the io workqueue is sized, how io requests are scheduled, and what the priorities are. Let's see what's in there.
24/2	2026/09/15 13:04	tool	grepper	0m Args: { "Expression": "io-wq\\.o", "PathPrefix": "io_uring/" } Results: { "Output": "io_uring/Makefile=19=obj-$(CONFIG_IO_URING_ZCRX)\t+= zcrx.o\nio_uring/Makefile:20:obj-$(CONFIG_IO_WQ)\t\t+= io-wq.o\nio_uring/Makefile-21-obj-$(CONFIG_FUTEX)\t\t+= futex.o\n" }
25/2	2026/09/15 13:04	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 26010 output: 28 thoughts: 15 Thoughts: Here's my summary, as though I'm thinking it: Digging into IO Workqueues Okay, so I need to understand this `CONFIG_IO_WQ` option in the kernel configuration. I'm going to start by getting a handle on exactly what it does, because I've encountered this before. I know it's related to asynchronous I/O, but I want to be sure I understand its implications. I should really check the Kconfig file directly and see what the help text says. That's the best place to start, it should give a clear high-level overview. Let's see what the dependencies are, and where it's used within the broader I/O subsystem. This will allow me to build a more complete understanding of why it's enabled or disabled in different configurations. Let's dive in and see what the Kconfig reveals!
26/2	2026/09/15 13:04	tool	grepper	0m Error: no matches Args: { "Expression": "config IO_WQ", "PathPrefix": "io_uring/" } Results: { "error": "no matches" }
27/2	2026/09/15 13:04	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 26257 output: 18 thoughts: 13 Thoughts: Okay, here's my take on those thoughts, tailored for an expert audience and presented in the first person: Analyzing Kconfig for IO_WQ References Right, let's get down to brass tacks. My initial thought process? It's time to leverage the power of `grep`. We need to deeply understand the dependencies, configuration options, and implications surrounding `IO_WQ` within the kernel configuration system, Kconfig. A simple `grep` across the Kconfig files is the most efficient way to start, the first thing that's running through my mind. This initial scan will reveal direct mentions, variable usage, and conditional relationships related to `IO_WQ` that might not be immediately obvious. This foundational data will allow me to narrow my focus and dig into the significant sections.
28/2	2026/09/15 13:04	tool	grepper	0m Args: { "Expression": "config IO_WQ" } Results: { "Output": "fs/Kconfig=419=source \"fs/unicode/Kconfig\"\nfs/Kconfig-420-\nfs/Kconfig:421:config IO_WQ\nfs/Kconfig-422-\tbool\n" }
29/2	2026/09/15 13:04	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 26522 output: 27 thoughts: 24 Thoughts: Here's my take on those thoughts: Investigating the IO_WQ Dependency Landscape Okay, so I need to figure out which configuration options are selecting `IO_WQ`. This is probably to understand the dependencies and how different parts of the kernel are using the workqueue infrastructure. I'll need to dig into the `fs/Kconfig` and `io_uring/Kconfig` files. I'm guessing that’s where the relevant configuration options that select or depend on `IO_WQ` are defined. This is likely part of a broader effort to assess the impact of changes to the I/O workqueue or to understand how various subsystems are leveraging it. Let's get to it!
30/2	2026/09/15 13:05	tool	grepper	0m Args: { "Expression": "IO_WQ", "PathPrefix": "io_uring/" } Results: { "Output": "io_uring/Makefile=19=obj-$(CONFIG_IO_URING_ZCRX)\t+= zcrx.o\nio_uring/Makefile:20:obj-$(CONFIG_IO_WQ)\t\t+= io-wq.o\nio_uring/Makefile-21-obj-$(CONFIG_FUTEX)\t\t+= futex.o\n--\nio_uring/cancel.c=78=static int io_async_cancel_one(struct io_uring_task tctx,\n--\nio_uring/cancel.c-90-\tswitch (cancel_ret) {\nio_uring/cancel.c:91:\tcase IO_WQ_CANCEL_OK:\nio_uring/cancel.c-92-\t\tret = 0;\nio_uring/cancel.c-93-\t\tbreak;\nio_uring/cancel.c:94:\tcase IO_WQ_CANCEL_RUNNING:\nio_uring/cancel.c-95-\t\tret = -EALREADY;\nio_uring/cancel.c-96-\t\tbreak;\nio_uring/cancel.c:97:\tcase IO_WQ_CANCEL_NOTFOUND:\nio_uring/cancel.c-98-\t\tret = -ENOENT;\n--\nio_uring/cancel.c=489=static __cold bool io_uring_try_cancel_iowq(struct io_ring_ctx ctx)\n--\nio_uring/cancel.c-506-\t\tcret = io_wq_cancel_cb(tctx-\u003eio_wq, io_cancel_ctx_cb, ctx, true);\nio_uring/cancel.c:507:\t\tret \|= (cret != IO_WQ_CANCEL_NOTFOUND);\nio_uring/cancel.c-508-\t}\n--\nio_uring/cancel.c=515=__cold bool io_uring_try_cancel_requests(struct io_ring_ctx ctx,\n--\nio_uring/cancel.c-541-\t\t\t\t \u0026cancel, true);\nio_uring/cancel.c:542:\t\tret \|= (cret != IO_WQ_CANCEL_NOTFOUND);\nio_uring/cancel.c-543-\t}\n--\nio_uring/io-wq.c=37=enum {\nio_uring/io-wq.c:38:\tIO_WQ_BIT_EXIT\t\t= 0,\t/ wq exiting /\nio_uring/io-wq.c:39:\tIO_WQ_BIT_EXIT_ON_IDLE\t= 1,\t/ allow all workers to exit on idle /\nio_uring/io-wq.c-40-};\n--\nio_uring/io-wq.c=49=struct io_worker {\n--\nio_uring/io-wq.c-73-#if BITS_PER_LONG == 64\nio_uring/io-wq.c:74:#define IO_WQ_HASH_ORDER\t6\nio_uring/io-wq.c-75-#else\nio_uring/io-wq.c:76:#define IO_WQ_HASH_ORDER\t5\nio_uring/io-wq.c-77-#endif\nio_uring/io-wq.c-78-\nio_uring/io-wq.c:79:#define IO_WQ_NR_HASH_BUCKETS\t(1u \u003c\u003c IO_WQ_HASH_ORDER)\nio_uring/io-wq.c-80-\n--\nio_uring/io-wq.c=108=enum {\nio_uring/io-wq.c:109:\tIO_WQ_ACCT_BOUND,\nio_uring/io-wq.c:110:\tIO_WQ_ACCT_UNBOUND,\nio_uring/io-wq.c:111:\tIO_WQ_ACCT_NR,\nio_uring/io-wq.c-112-};\n--\nio_uring/io-wq.c=117=struct io_wq {\n--\nio_uring/io-wq.c-128-\nio_uring/io-wq.c:129:\tstruct io_wq_acct acct[IO_WQ_ACCT_NR];\nio_uring/io-wq.c-130-\n--\nio_uring/io-wq.c-132-\nio_uring/io-wq.c:133:\tstruct io_wq_work hash_tail[IO_WQ_NR_HASH_BUCKETS];\nio_uring/io-wq.c-134-\n--\nio_uring/io-wq.c=156=static inline unsigned int __io_get_work_hash(unsigned int work_flags)\nio_uring/io-wq.c-157-{\nio_uring/io-wq.c:158:\treturn work_flags \u003e\u003e IO_WQ_HASH_SHIFT;\nio_uring/io-wq.c-159-}\n--\nio_uring/io-wq.c=177=static inline struct io_wq_acct io_get_acct(struct io_wq wq, bool bound)\nio_uring/io-wq.c-178-{\nio_uring/io-wq.c:179:\treturn \u0026wq-\u003eacct[bound ? IO_WQ_ACCT_BOUND : IO_WQ_ACCT_UNBOUND];\nio_uring/io-wq.c-180-}\n--\nio_uring/io-wq.c=182=static inline struct io_wq_acct io_work_get_acct(struct io_wq wq,\n--\nio_uring/io-wq.c-184-{\nio_uring/io-wq.c:185:\treturn io_get_acct(wq, !(work_flags \u0026 IO_WQ_WORK_UNBOUND));\nio_uring/io-wq.c-186-}\n--\nio_uring/io-wq.c=199=bool io_wq_worker_stopped(void)\n--\nio_uring/io-wq.c-205-\nio_uring/io-wq.c:206:\treturn test_bit(IO_WQ_BIT_EXIT, \u0026worker-\u003ewq-\u003estate);\nio_uring/io-wq.c-207-}\n--\nio_uring/io-wq.c=391=static bool io_queue_worker_create(struct io_worker worker,\n--\nio_uring/io-wq.c-397-\t/ raced with exit, just ignore create call /\nio_uring/io-wq.c:398:\tif (test_bit(IO_WQ_BIT_EXIT, \u0026wq-\u003estate))\nio_uring/io-wq.c-399-\t\tgoto fail;\n--\nio_uring/io-wq.c-420-\t\t /\nio_uring/io-wq.c:421:\t\tif (test_bit(IO_WQ_BIT_EXIT, \u0026wq-\u003estate))\nio_uring/io-wq.c-422-\t\t\tio_wq_cancel_tw_create(wq);\n--\nio_uring/io-wq.c=602=static void io_worker_handle_work(struct io_wq_acct acct,\n--\nio_uring/io-wq.c-643-\t\tdo {\nio_uring/io-wq.c:644:\t\t\tbool do_kill = test_bit(IO_WQ_BIT_EXIT, \u0026wq-\u003estate);\nio_uring/io-wq.c-645-\t\t\tstruct io_wq_work next_hashed, linked;\n--\nio_uring/io-wq.c-654-\t\t\tif (do_kill \u0026\u0026\nio_uring/io-wq.c:655:\t\t\t (work_flags \u0026 IO_WQ_WORK_UNBOUND))\nio_uring/io-wq.c:656:\t\t\t\tatomic_or(IO_WQ_WORK_CANCEL, \u0026work-\u003eflags);\nio_uring/io-wq.c-657-\t\t\treq = container_of(work, struct io_kiocb, work);\n--\nio_uring/io-wq.c=690=static int io_wq_worker(void data)\n--\nio_uring/io-wq.c-703-\nio_uring/io-wq.c:704:\twhile (!test_bit(IO_WQ_BIT_EXIT, \u0026wq-\u003estate)) {\nio_uring/io-wq.c-705-\t\tlong ret;\n--\nio_uring/io-wq.c-724-\t\tif ((last_timeout \u0026\u0026 (exit_mask \|\| acct-\u003enr_workers \u003e 1)) \|\|\nio_uring/io-wq.c:725:\t\t test_bit(IO_WQ_BIT_EXIT_ON_IDLE, \u0026wq-\u003estate)) {\nio_uring/io-wq.c-726-\t\t\tacct-\u003enr_workers--;\n--\nio_uring/io-wq.c-750-\nio_uring/io-wq.c:751:\tif (test_bit(IO_WQ_BIT_EXIT, \u0026wq-\u003estate) \u0026\u0026 io_acct_run_queue(acct))\nio_uring/io-wq.c-752-\t\tio_worker_handle_work(acct, worker);\n--\nio_uring/io-wq.c=964=static void io_wq_for_each_worker(struct io_wq wq,\n--\nio_uring/io-wq.c-967-{\nio_uring/io-wq.c:968:\tfor (int i = 0; i \u003c IO_WQ_ACCT_NR; i++)\nio_uring/io-wq.c-969-\t\tif (io_acct_for_each_worker(\u0026wq-\u003eacct[i], func, data))\n--\nio_uring/io-wq.c=980=void io_wq_set_exit_on_idle(struct io_wq wq, bool enable)\n--\nio_uring/io-wq.c-985-\tif (!enable) {\nio_uring/io-wq.c:986:\t\tclear_bit(IO_WQ_BIT_EXIT_ON_IDLE, \u0026wq-\u003estate);\nio_uring/io-wq.c-987-\t\treturn;\n--\nio_uring/io-wq.c-989-\nio_uring/io-wq.c:990:\tif (test_and_set_bit(IO_WQ_BIT_EXIT_ON_IDLE, \u0026wq-\u003estate))\nio_uring/io-wq.c-991-\t\treturn;\n--\nio_uring/io-wq.c=998=static void io_run_cancel(struct io_wq_work work, struct io_wq wq)\n--\nio_uring/io-wq.c-1000-\tdo {\nio_uring/io-wq.c:1001:\t\tatomic_or(IO_WQ_WORK_CANCEL, \u0026work-\u003eflags);\nio_uring/io-wq.c-1002-\t\tio_wq_submit_work(work);\n--\nio_uring/io-wq.c=1033=void io_wq_enqueue(struct io_wq wq, struct io_wq_work work)\n--\nio_uring/io-wq.c-1047-\t /\nio_uring/io-wq.c:1048:\tif (test_bit(IO_WQ_BIT_EXIT, \u0026wq-\u003estate) \|\|\nio_uring/io-wq.c:1049:\t (work_flags \u0026 IO_WQ_WORK_CANCEL)) {\nio_uring/io-wq.c-1050-\t\tio_run_cancel(work, wq);\n--\nio_uring/io-wq.c-1062-\nio_uring/io-wq.c:1063:\tif (do_create \u0026\u0026 ((work_flags \u0026 IO_WQ_WORK_CONCURRENT) \|\|\nio_uring/io-wq.c-1064-\t !atomic_read(\u0026acct-\u003enr_running))) {\n--\nio_uring/io-wq.c=1087=void io_wq_hash_work(struct io_wq_work work, void val)\n--\nio_uring/io-wq.c-1090-\nio_uring/io-wq.c:1091:\tbit = hash_ptr(val, IO_WQ_HASH_ORDER);\nio_uring/io-wq.c:1092:\tatomic_or(IO_WQ_WORK_HASHED \| (bit \u003c\u003c IO_WQ_HASH_SHIFT), \u0026work-\u003eflags);\nio_uring/io-wq.c-1093-}\n--\nio_uring/io-wq.c=1095=static bool __io_wq_worker_cancel(struct io_worker worker,\n--\nio_uring/io-wq.c-1099-\tif (work \u0026\u0026 match-\u003efn(work, match-\u003edata)) {\nio_uring/io-wq.c:1100:\t\tatomic_or(IO_WQ_WORK_CANCEL, \u0026work-\u003eflags);\nio_uring/io-wq.c-1101-\t\t__set_notify_signal(worker-\u003etask);\n--\nio_uring/io-wq.c=1168=static void io_wq_cancel_pending_work(struct io_wq wq,\n--\nio_uring/io-wq.c-1172-retry:\nio_uring/io-wq.c:1173:\tfor (i = 0; i \u003c IO_WQ_ACCT_NR; i++) {\nio_uring/io-wq.c-1174-\t\tstruct io_wq_acct acct = io_get_acct(wq, i == 0);\n--\nio_uring/io-wq.c=1192=static void io_wq_cancel_running_work(struct io_wq wq,\n--\nio_uring/io-wq.c-1196-\nio_uring/io-wq.c:1197:\tfor (int i = 0; i \u003c IO_WQ_ACCT_NR; i++)\nio_uring/io-wq.c-1198-\t\tio_acct_cancel_running_work(\u0026wq-\u003eacct[i], match);\n--\nio_uring/io-wq.c=1203=enum io_wq_cancel io_wq_cancel_cb(struct io_wq wq, work_cancel_fn cancel,\n--\nio_uring/io-wq.c-1226-\tif (match.nr_pending \u0026\u0026 !match.cancel_all)\nio_uring/io-wq.c:1227:\t\treturn IO_WQ_CANCEL_OK;\nio_uring/io-wq.c-1228-\n--\nio_uring/io-wq.c-1230-\tif (match.nr_running \u0026\u0026 !match.cancel_all)\nio_uring/io-wq.c:1231:\t\treturn IO_WQ_CANCEL_RUNNING;\nio_uring/io-wq.c-1232-\nio_uring/io-wq.c-1233-\tif (match.nr_running)\nio_uring/io-wq.c:1234:\t\treturn IO_WQ_CANCEL_RUNNING;\nio_uring/io-wq.c-1235-\tif (match.nr_pending)\nio_uring/io-wq.c:1236:\t\treturn IO_WQ_CANCEL_OK;\nio_uring/io-wq.c:1237:\treturn IO_WQ_CANCEL_NOTFOUND;\nio_uring/io-wq.c-1238-}\n--\nio_uring/io-wq.c=1240=static int io_wq_hash_wake(struct wait_queue_entry wait, unsigned mode,\n--\nio_uring/io-wq.c-1248-\trcu_read_lock();\nio_uring/io-wq.c:1249:\tfor (i = 0; i \u003c IO_WQ_ACCT_NR; i++) {\nio_uring/io-wq.c-1250-\t\tstruct io_wq_acct acct = \u0026wq-\u003eacct[i];\n--\nio_uring/io-wq.c=1259=struct io_wq io_wq_create(unsigned bounded, struct io_wq_data data)\n--\nio_uring/io-wq.c-1278-\tcpuset_cpus_allowed(data-\u003etask, wq-\u003ecpu_mask);\nio_uring/io-wq.c:1279:\twq-\u003eacct[IO_WQ_ACCT_BOUND].max_workers = bounded;\nio_uring/io-wq.c:1280:\twq-\u003eacct[IO_WQ_ACCT_UNBOUND].max_workers =\nio_uring/io-wq.c-1281-\t\t\t\ttask_rlimit(current, RLIMIT_NPROC);\n--\nio_uring/io-wq.c-1283-\twq-\u003ewait.func = io_wq_hash_wake;\nio_uring/io-wq.c:1284:\tfor (i = 0; i \u003c IO_WQ_ACCT_NR; i++) {\nio_uring/io-wq.c-1285-\t\tstruct io_wq_acct acct = \u0026wq-\u003eacct[i];\n--\nio_uring/io-wq.c=1324=void io_wq_exit_start(struct io_wq wq)\nio_uring/io-wq.c-1325-{\nio_uring/io-wq.c:1326:\tset_bit(IO_WQ_BIT_EXIT, \u0026wq-\u003estate);\nio_uring/io-wq.c-1327-\t/ Pairs with task_work_add() in io_queue_worker_create(). /\n--\nio_uring/io-wq.c=1405=void io_wq_put_and_exit(struct io_wq wq)\nio_uring/io-wq.c-1406-{\nio_uring/io-wq.c:1407:\tWARN_ON_ONCE(!test_bit(IO_WQ_BIT_EXIT, \u0026wq-\u003estate));\nio_uring/io-wq.c-1408-\n--\nio_uring/io-wq.c=1487=int io_wq_max_workers(struct io_wq wq, int new_count)\n--\nio_uring/io-wq.c-1489-\tstruct io_wq_acct acct;\nio_uring/io-wq.c:1490:\tint prev[IO_WQ_ACCT_NR];\nio_uring/io-wq.c-1491-\tint i;\nio_uring/io-wq.c-1492-\nio_uring/io-wq.c:1493:\tBUILD_BUG_ON((int) IO_WQ_ACCT_BOUND != (int) IO_WQ_BOUND);\nio_uring/io-wq.c:1494:\tBUILD_BUG_ON((int) IO_WQ_ACCT_UNBOUND != (int) IO_WQ_UNBOUND);\nio_uring/io-wq.c:1495:\tBUILD_BUG_ON((int) IO_WQ_ACCT_NR != 2);\nio_uring/io-wq.c-1496-\nio_uring/io-wq.c:1497:\tfor (i = 0; i \u003c IO_WQ_ACCT_NR; i++) {\nio_uring/io-wq.c-1498-\t\tif (new_count[i] \u003e task_rlimit(current, RLIMIT_NPROC))\n--\nio_uring/io-wq.c-1501-\nio_uring/io-wq.c:1502:\tfor (i = 0; i \u003c IO_WQ_ACCT_NR; i++)\nio_uring/io-wq.c-1503-\t\tprev[i] = 0;\n--\nio_uring/io-wq.c-1506-\nio_uring/io-wq.c:1507:\tfor (i = 0; i \u003c IO_WQ_ACCT_NR; i++) {\nio_uring/io-wq.c-1508-\t\tacct = \u0026wq-\u003eacct[i];\n--\nio_uring/io-wq.c-1516-\nio_uring/io-wq.c:1517:\tfor (i = 0; i \u003c IO_WQ_ACCT_NR; i++)\nio_uring/io-wq.c-1518-\t\tnew_count[i] = prev[i];\n--\nio_uring/io-wq.h-1-/ SPDX-License-Identifier: GPL-2.0 /\nio_uring/io-wq.h:2:#ifndef INTERNAL_IO_WQ_H\nio_uring/io-wq.h:3:#define INTERNAL_IO_WQ_H\nio_uring/io-wq.h-4-\n--\nio_uring/io-wq.h=10=enum {\nio_uring/io-wq.h:11:\tIO_WQ_WORK_CANCEL\t= 1,\nio_uring/io-wq.h:12:\tIO_WQ_WORK_HASHED\t= 2,\nio_uring/io-wq.h:13:\tIO_WQ_WORK_UNBOUND\t= 4,\nio_uring/io-wq.h:14:\tIO_WQ_WORK_CONCURRENT\t= 16,\nio_uring/io-wq.h-15-\nio_uring/io-wq.h:16:\tIO_WQ_HASH_SHIFT\t= 24,\t/ upper 8 bits are used for hash key /\nio_uring/io-wq.h-17-};\n--\nio_uring/io-wq.h=19=enum io_wq_cancel {\nio_uring/io-wq.h:20:\tIO_WQ_CANCEL_OK,\t/ cancelled before started /\nio_uring/io-wq.h:21:\tIO_WQ_CANCEL_RUNNING,\t/ found, running, and attempted cancelled /\nio_uring/io-wq.h:22:\tIO_WQ_CANCEL_NOTFOUND,\t/ work not found /\nio_uring/io-wq.h-23-};\n--\nio_uring/io-wq.h=54=static inline bool __io_wq_is_hashed(unsigned int work_flags)\nio_uring/io-wq.h-55-{\nio_uring/io-wq.h:56:\treturn work_flags \u0026 IO_WQ_WORK_HASHED;\nio_uring/io-wq.h-57-}\n--\nio_uring/io-wq.h=66=enum io_wq_cancel io_wq_cancel_cb(struct io_wq wq, work_cancel_fn cancel,\n--\nio_uring/io-wq.h-68-\nio_uring/io-wq.h:69:#if defined(CONFIG_IO_WQ)\nio_uring/io-wq.h-70-extern void io_wq_worker_sleeping(struct task_struct );\n--\nio_uring/io_uring.c=361=static void io_prep_async_work(struct io_kiocb req)\n--\nio_uring/io_uring.c-372-\tif (req-\u003eflags \u0026 REQ_F_FORCE_ASYNC)\nio_uring/io_uring.c:373:\t\tatomic_or(IO_WQ_WORK_CONCURRENT, \u0026req-\u003ework.flags);\nio_uring/io_uring.c-374-\n--\nio_uring/io_uring.c-388-\t\tif (def-\u003eunbound_nonreg_file)\nio_uring/io_uring.c:389:\t\t\tatomic_or(IO_WQ_WORK_UNBOUND, \u0026req-\u003ework.flags);\nio_uring/io_uring.c-390-\t}\n--\nio_uring/io_uring.c=410=void io_queue_iowq(struct io_kiocb req)\n--\nio_uring/io_uring.c-431-\tif (WARN_ON_ONCE(!same_thread_group(tctx-\u003etask, current)))\nio_uring/io_uring.c:432:\t\tatomic_or(IO_WQ_WORK_CANCEL, \u0026req-\u003ework.flags);\nio_uring/io_uring.c-433-\n--\nio_uring/io_uring.c=1466=void io_wq_submit_work(struct io_wq_work work)\n--\nio_uring/io_uring.c-1480-\t/ either cancelled or io-wq is dying, so don't touch tctx-\u003eiowq /\nio_uring/io_uring.c:1481:\tif (atomic_read(\u0026work-\u003eflags) \u0026 IO_WQ_WORK_CANCEL) {\nio_uring/io_uring.c-1482-fail:\n--\nio_uring/io_uring.c-1487-\t\terr = -EBADF;\nio_uring/io_uring.c:1488:\t\tatomic_or(IO_WQ_WORK_CANCEL, \u0026work-\u003eflags);\nio_uring/io_uring.c-1489-\t\tgoto fail;\n--\nio_uring/poll.c=34=struct io_poll_table {\n--\nio_uring/poll.c-53-\nio_uring/poll.c:54:#define IO_WQE_F_DOUBLE\t\t1\nio_uring/poll.c-55-\n--\nio_uring/poll.c=59=static inline struct io_kiocb wqe_to_req(struct wait_queue_entry wqe)\n--\nio_uring/poll.c-62-\nio_uring/poll.c:63:\treturn (struct io_kiocb )(priv \u0026 ~IO_WQE_F_DOUBLE);\nio_uring/poll.c-64-}\n--\nio_uring/poll.c=66=static inline bool wqe_is_double(struct wait_queue_entry wqe)\n--\nio_uring/poll.c-69-\nio_uring/poll.c:70:\treturn priv \u0026 IO_WQE_F_DOUBLE;\nio_uring/poll.c-71-}\n--\nio_uring/poll.c=465=static void __io_queue_proc(struct io_poll poll, struct io_poll_table pt,\n--\nio_uring/poll.c-497-\t\t/ mark as double wq entry */\nio_uring/poll.c:498:\t\twqe_private \|= IO_WQE_F_DOUBLE;\nio_uring/poll.c-499-\t\tio_init_poll_iocb(poll, first-\u003eevents);\n" }
31/2	2026/09/15 13:05	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 33360 output: 25 thoughts: 33 Thoughts: Okay, here's the summary, rendered as a first-person thought process, aimed at an expert audience: IO_URING Configuration Dependency Right, let's break this down. My initial hunch is confirmed: `CONFIG_IO_URING` does seem to be pulling in `CONFIG_IO_WQ`. A quick mental check indicates that's likely the case, as it makes sense for it to leverage the workqueues. But, better be sure before I move forward, or commit to a design based on this premise. So, I should explicitly check the `io_uring/Kconfig` file. I'll need to confirm that `CONFIG_IO_URING` explicitly depends on, or otherwise implies, `CONFIG_IO_WQ`, probably via a `select` statement. Gotta verify the exact mechanism, of course.
32/2	2026/09/15 13:05	tool	grepper	0m Args: { "Expression": "IO_WQ", "PathPrefix": "init/" } Results: { "Output": "init/Kconfig=1960=config IO_URING\ninit/Kconfig-1961-\tbool \"Enable IO uring support\" if EXPERT\ninit/Kconfig:1962:\tselect IO_WQ\ninit/Kconfig-1963-\tdefault y\n" }
33/2	2026/09/15 13:05	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 33676 output: 30 thoughts: 590 Thoughts: Analyzing the Coredump Patch Okay, so `CONFIG_IO_URING` naturally selects `IO_WQ`, that's expected. And `CONFIG_COREDUMP` is standard, nothing surprising there. Let's delve deeper and check for any other configuration dependencies for coredump functionality or anything in this patch. Looking at `fs/coredump.c`, specifically `check_coredump_socket()`, I'm wondering if socket coredumps need any special configurations. Line 1776 has that `#ifdef CONFIG_UNIX`. Unix domain sockets (`UNIX`) are pretty standard, thankfully. And, of course, `COREDUMP`. Let's just confirm `COREDUMP` in `fs/Kconfig.binfmt`: yup, it's just a boolean config option. Alright, let's get into the actual code changes in this patch, carefully examining the FocusSymbols. So, `fs/coredump.c` is the primary focus: * In `coredump_parse`, they've added `core_pattern_lock` around copying `core_pattern` to a local buffer. Good, prevents races. * In `coredump_close_files`, they've fixed a potential NULL pointer dereference with a nice check for `current->files`. If it's NULL, it does `put_files_struct(files)` and if there are files, it calls `switch_files_struct(current, files)`. Makes sense. * `coredump_finish` now includes an RCU read lock, which is `guard(rcu)();`, which is good for synchronization when waking threads. Smart. * `check_coredump_socket` now takes the `pattern` as an argument. That's a clean refactoring. * `proc_dostring_coredump` has been completely rewritten for pattern copying and validation, also under the `core_pattern_lock` before publishing to `core_pattern`. Excellent, consistency. * `vfs_coredump` and `do_coredump` are just callers of the other functions. Then we have `include/linux/sched/signal.h`: * A check has been added to `signal_pending`. It looks like `if (unlikely(READ_ONCE(p->flags) & PF_DUMPCORE)) return __fatal_signal_pending(p);` This is a key change. It's an inlined function, which means the compiler will put the code inline at each call site, rather than creating a function call. Per the instructions, since this function is inlined we will need to identify the feature specific caller functions in `.c` files to target this changes. We need to check who calls it during coredumping. Looking through the code I see `dump_interrupted` in `fs/coredump.c`. Let's verify what `dump_interrupted` does.
34/2	2026/09/15 13:05	tool	grepper	0m Args: { "Expression": "dump_interrupted", "PathPrefix": "fs/coredump.c" } Results: { "Output": "fs/coredump.c=600=static void coredump_finish(enum coredump_state state)\n--\nfs/coredump.c-626-\nfs/coredump.c:627:static bool dump_interrupted(void)\nfs/coredump.c-628-{\n--\nfs/coredump.c=638=static void wait_for_dump_helpers(struct file file)\n--\nfs/coredump.c-650-\t We actually want wait_event_freezable() but then we need\nfs/coredump.c:651:\t * to clear TIF_SIGPENDING and improve dump_interrupted().\nfs/coredump.c-652-\t /\n--\nfs/coredump.c=1182=static bool coredump_write(struct coredump_params cprm,\n--\nfs/coredump.c-1184-{\nfs/coredump.c:1185:\tif (dump_interrupted()) {\nfs/coredump.c-1186-\t\tcprm-\u003estate \|= COREDUMP_STATE_TRUNCATED;\n--\nfs/coredump.c=1417=static bool dump_emit_chunk(struct coredump_params cprm, const void addr,\n--\nfs/coredump.c-1424-\nfs/coredump.c:1425:\tif (dump_interrupted())\nfs/coredump.c-1426-\t\treturn false;\n--\nfs/coredump.c=1489=static bool __dump_skip(struct coredump_params cprm, size_t nr)\n--\nfs/coredump.c-1495-\t\t/ Hand the server the length of the hole instead of the hole itself. /\nfs/coredump.c:1496:\t\tif (dump_interrupted())\nfs/coredump.c-1497-\t\t\treturn false;\n--\nfs/coredump.c-1501-\tif (file-\u003ef_mode \u0026 FMODE_LSEEK) {\nfs/coredump.c:1502:\t\tif (dump_interrupted() \|\| vfs_llseek(file, nr, SEEK_CUR) \u003c 0)\nfs/coredump.c-1503-\t\t\treturn false;\n--\nfs/coredump.c=1554=static bool dump_emit_page(struct coredump_params cprm, struct page page)\n--\nfs/coredump.c-1567-\t\treturn false;\nfs/coredump.c:1568:\tif (dump_interrupted())\nfs/coredump.c-1569-\t\treturn false;\n--\nfs/coredump.c=1611=bool dump_user_range(struct coredump_params cprm, unsigned long start,\n--\nfs/coredump.c-1654-\nfs/coredump.c:1655:\t\tif (dump_interrupted())\nfs/coredump.c-1656-\t\t\tgoto out;\n" }
35/2	2026/09/15 13:05	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 35706 output: 34 thoughts: 10 Thoughts: Okay, here's my interpretation of that thought process, tailored for an expert audience, and written in the first person: Analyzing Interruption Handling Alright, let's dive into this. The immediate thought here is to examine the `dump_interrupted` function or variable. The fact that it's highlighted specifically suggests we're dealing with a critical point in the system's interrupt handling. I'm likely debugging a scenario where an interruption is causing unexpected behavior – perhaps a crash, data corruption, or simply an incorrect state. "Dump" implies we're trying to capture diagnostic information related to the interruption. My focus is likely on how the system reacts to these interrupts. Is the system correctly identifying the interrupt source? Are the interrupt handlers functioning as expected? Does the `dump_interrupted` variable, function or module provide sufficient context to determine what happened immediately before the interruption? We're probably looking to trace back the execution path to understand the sequence of events and pinpoint the root cause of the problem. Are there race conditions? Is the interrupt mask being handled appropriately? Is it happening only in particular circumstances? Let's get to the bottom of this.
36/2	2026/09/15 13:05	tool	read-file	0m Args: { "File": "fs/coredump.c", "FirstLine": 625, "LineCount": 15 } Results: { "Contents": " 625:\t}\n 626:\t\n 627:\tstatic bool dump_interrupted(void)\n 628:\t{\n 629:\t\t/\n 630:\t\t SIGKILL or freezing() interrupt the coredumping. Perhaps we\n 631:\t\t * can do try_to_freeze() and check __fatal_signal_pending(),\n 632:\t\t * but then we need to teach dump_write() to restart and clear\n 633:\t\t * TIF_SIGPENDING.\n 634:\t\t /\n 635:\t\treturn fatal_signal_pending(current) \|\| freezing(current);\n 636:\t}\n 637:\t\n 638:\tstatic void wait_for_dump_helpers(struct file file)\n 639:\t{\n" }
37/2	2026/09/15 13:05	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 36211 output: 19 thoughts: 769 Thoughts: Analyzing Core Dump Focus Symbols Okay, so I'm digging into this `signal_pending` thing and how it interacts with core dumps. The key realization is that when a task is dumping core, it might be doing I/O, hitting locks, semaphores, and the kernel checks `signal_pending(current)` in all those places. The behavior of `signal_pending` has been altered. Previously any non-fatal signal would cause it to return 1. Now, if `PF_DUMPCORE` is set, it ignores non-fatal signals and only checks for fatal ones. Fine, that makes sense. Then I hit `kernel/fork.c` and specifically `copy_process`. It's checking `current->signal->core_state`. Why? Ah, right. If another thread in the thread group initiated a coredump, `core_state` is allocated and set. A thread shouldn't be forking while this is happening. The problem is `copy_process` is, in essence, called all the time. Syzkaller uses `clone`/`fork` constantly. If I put `copy_process` on the focus list, I'm going to match EVERY single test run by syzkaller. That is absolutely not what I want. Now, I need to refer back to Section 4. Avoid ubiquitous lifecycle hot-paths! Don't list general, ubiquitous functions like allocators, page fault handlers, or core synchronization primitives. It says listing these kinds of functions dilutes the fuzzing effort. It also says to target specific feature logic and entrypoints. Okay, that's the guiding principle. So, `copy_process` is definitely out. It's too generic. Let's look at more specific options. What about `io_wq_exit_start`? Is that ubiquitous? No, it's specific to io-wq exiting, which is fine. Let's look at functions in `fs/coredump.c` – `coredump_parse`, `coredump_close_files`, `coredump_finish`, `proc_dostring_coredump`, `do_coredump`, and `vfs_coredump`. These are all related to the core dump feature which sounds perfect, but I need to make sure they're actually relevant to the changes. I need to quickly confirm that these functions are actually in the vmlinux symbols. Specifically, I'm going to examine `vfs_coredump`. Let's see... `void vfs_coredump(const kernel_siginfo_t siginfo)` – looks like it's non-static, so it is* exported. Now, let's see where it's called.
38/2	2026/09/15 13:05	tool	grepper	0m Args: { "Expression": "vfs_coredump" } Results: { "Output": "Documentation/security/credentials.rst=553=different set of credentials. This is done in the following places:\n--\nDocumentation/security/credentials.rst-555- * ``sys_faccessat()``.\nDocumentation/security/credentials.rst:556: * ``vfs_coredump()``.\nDocumentation/security/credentials.rst-557- * nfs4recover.c.\n--\nDocumentation/translations/zh_CN/security/credentials.rst=254=const指针上操作，因此不需要进行类型转换，但需要临时放弃const限定，以便能够修改\n--\nDocumentation/translations/zh_CN/security/credentials.rst-475- * ``sys_faccessat()``.\nDocumentation/translations/zh_CN/security/credentials.rst:476: * ``vfs_coredump()``.\nDocumentation/translations/zh_CN/security/credentials.rst-477- * nfs4recover.c.\n--\nfs/coredump.c=1247=static void do_coredump(struct core_name cn, struct coredump_params cprm,\n--\nfs/coredump.c-1318-\nfs/coredump.c:1319:void vfs_coredump(const kernel_siginfo_t siginfo)\nfs/coredump.c-1320-{\n--\ninclude/linux/coredump.h=67=bool dump_user_range(struct coredump_params cprm, unsigned long start,\ninclude/linux/coredump.h-68-\t\t unsigned long len);\ninclude/linux/coredump.h:69:void vfs_coredump(const kernel_siginfo_t siginfo);\ninclude/linux/coredump.h-70-\n--\ninclude/linux/coredump.h-88-#else\ninclude/linux/coredump.h:89:static inline void vfs_coredump(const kernel_siginfo_t siginfo) {}\ninclude/linux/coredump.h-90-\n--\nkernel/signal.c=2815=bool get_signal(struct ksignal ksig)\n--\nkernel/signal.c-3035-\t\t\t /\nkernel/signal.c:3036:\t\t\tvfs_coredump(\u0026ksig-\u003einfo);\nkernel/signal.c-3037-\t\t}\n" }
39/2	2026/09/15 13:05	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 38158 output: 22 thoughts: 117 Thoughts: My Core Dump Investigation Okay, so I'm looking at how core dumps are handled in this system. I see that `vfs_coredump` is the entry point, triggered from `kernel/signal.c` when a core-dumping fatal signal lands. `vfs_coredump` is essentially the orchestrator; it calls `do_coredump` and `coredump_finish`. Naturally, my interest is piqued by `do_coredump` since it's the real workhorse, calling functions like `coredump_parse` and `coredump_close_files`. Now, the `core_pattern` sysctl variable is clearly critical to the actual dump destination, and I've found that `proc_dostring_coredump` is the handler for that sysctl entry. I'll need to understand what this handler does. I should check how it is used to get a better overview of the core dump process. Let me quickly grep for references to `proc_dostring_coredump`.
40/2	2026/09/15 13:05	tool	grepper	0m Args: { "Expression": "proc_dostring_coredump" } Results: { "Output": "fs/coredump.c=1700=static inline bool check_coredump_socket(const char pattern)\n--\nfs/coredump.c-1738-\nfs/coredump.c:1739:static int proc_dostring_coredump(const struct ctl_table table, int write,\nfs/coredump.c-1740-\t\t void buffer, size_t lenp, loff_t *ppos)\n--\nfs/coredump.c=1781=static const struct ctl_table coredump_sysctls[] = {\n--\nfs/coredump.c-1793-\t\t.mode\t\t= 0644,\nfs/coredump.c:1794:\t\t.proc_handler\t= proc_dostring_coredump,\nfs/coredump.c-1795-\t},\n" }
41/2	2026/09/15 13:05	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 38744 output: 21 thoughts: 65 Thoughts: Analyzing Core Dumps and io_uring Workflow Okay, so `coredump_sysctls` seems to be the key function that's registering `proc_dostring_coredump`. That's important for understanding how the system is handling core dump configurations, which is always useful to know. I'm going to keep that in mind. Now, my focus is on `io_wq_exit_start` within `io_uring/io-wq.c`. I need to figure out what triggers this function. Since the name suggests it's related to the I/O workqueue exiting, the calling context of this function is going to give me valuable insights into the io_uring lifecycle and how things are cleaned up. So, next step, I'm going to dive deeper and list the callers of this function. I need to understand what's triggering `io_wq_exit_start` specifically.
42/2	2026/09/15 13:05	tool	grepper	0m Args: { "Expression": "io_wq_exit_start" } Results: { "Output": "io_uring/cancel.c=582=__cold void io_uring_cancel_generic(bool cancel_all, struct io_sq_data sqd)\n--\nio_uring/cancel.c-595-\tif (tctx-\u003eio_wq)\nio_uring/cancel.c:596:\t\tio_wq_exit_start(tctx-\u003eio_wq);\nio_uring/cancel.c-597-\n--\nio_uring/io-wq.c=1314=static bool io_task_work_match(struct callback_head cb, void data)\n--\nio_uring/io-wq.c-1323-\nio_uring/io-wq.c:1324:void io_wq_exit_start(struct io_wq wq)\nio_uring/io-wq.c-1325-{\n--\nio_uring/io-wq.h=42=struct io_wq io_wq_create(unsigned bounded, struct io_wq_data data);\nio_uring/io-wq.h:43:void io_wq_exit_start(struct io_wq wq);\nio_uring/io-wq.h-44-void io_wq_put_and_exit(struct io_wq wq);\n--\nio_uring/tctx.c=145=int __io_uring_add_tctx_node(struct io_ring_ctx *ctx)\n--\nio_uring/tctx.c-188-\t\tif (tctx-\u003eio_wq) {\nio_uring/tctx.c:189:\t\t\tio_wq_exit_start(tctx-\u003eio_wq);\nio_uring/tctx.c-190-\t\t\tio_wq_put_and_exit(tctx-\u003eio_wq);\n" }
43/2	2026/09/15 13:05	llm	patch-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 39477 output: 232 thoughts: 799 Thoughts: Analysis of Core Dump and IO_URING Configuration and Focus Symbols for Fuzzing Okay, let's break this down. First, I need to verify the necessary configurations. I'm looking at `COREDUMP` and `IO_URING`. `IO_URING` implies `IO_WQ`, which is good. I quickly checked `kernel/fork.c` and `include/linux/sched/signal.h` – they're always built, so no specific configuration there. `fs/coredump.c` is conditional on `CONFIG_COREDUMP`, and `io_uring/io-wq.c` hinges on `CONFIG_IO_WQ`, which `CONFIG_IO_URING` selects. Now, a more detailed look at the dependencies. `COREDUMP` from `fs/Kconfig.binfmt` is straightforward, a boolean with a default 'y' and an "if EXPERT" condition. No explicit `depends on`. `IO_URING` from `init/Kconfig` is also a boolean, defaults to 'y', "if EXPERT", but critically, it `select`s `IO_WQ`. So, my `EnableConfigs` list is confirmed: `["COREDUMP", "IO_URING"]`. Next, I need to identify the FocusSymbols. These are the specific functions touched by this change. I've identified the following: * `fs/coredump.c`: `vfs_coredump`, `do_coredump`, `coredump_parse`, `coredump_close_files`, `coredump_finish`, `proc_dostring_coredump`. * `io_uring/io-wq.c`: `io_wq_exit_start`. But I need to determine if all of these functions warrant inclusion in the `FocusSymbols`. Let's evaluate. `vfs_coredump` is the primary, non-static entrypoint for coredumps. `coredump_parse` has been modified to handle the `core_pattern_lock`. `coredump_close_files` has been altered. `coredump_finish` includes a `guard(rcu)();`. `proc_dostring_coredump` is the sysctl handler for `core_pattern`. And `io_wq_exit_start` includes `smp_mb__after_atomic();`. The changes here look significant. Now, what about `copy_process`? Syzkaller's reliance on forking suggests that this function is a ubiquitous hot-path in its tests, including it would produce a very large matchset and dilute the focus of this fuzzing campaign. So, I will exclude `copy_process`. Therefore, my final `FocusSymbols` list is: ``` [ "coredump_parse", "coredump_close_files", "coredump_finish", "proc_dostring_coredump", "vfs_coredump", "io_wq_exit_start" ] ``` Everything seems well-reasoned. The parameters for `set-results` will be as follows: * `WorthFuzzing`: true * `EnableConfigs`: `["COREDUMP", "IO_URING"]` * `FocusSymbols`: \[the above list] * `Reasoning`: Concise explanation, which will describe the rationale for fuzzing this patch, the race conditions being addressed, the changes relating to core locking, sysctl handling, signal logic, and the coredump lifecycle. I'm confident in this analysis. Ready to move forward with `set-results`.
44/2	2026/09/15 13:05	tool	set-results	0m Args: { "EnableConfigs": [ "COREDUMP", "IO_URING" ], "FocusSymbols": [ "coredump_parse", "coredump_close_files", "coredump_finish", "proc_dostring_coredump", "vfs_coredump", "io_wq_exit_start" ], "Reasoning": "The patch series modifies core kernel execution paths in fs/coredump.c, include/linux/sched/signal.h, kernel/fork.c, and io_uring/io-wq.c. Changes include synchronizing core_pattern reads/writes with a new spinlock (core_pattern_lock), guarding against NULL current-\u003efiles during coredump file teardown, adding RCU protection during thread completion wakeups in coredump_finish, refining signal_pending() for PF_DUMPCORE tasks, and adding memory barrier synchronization in io_wq_exit_start(). These modifications directly alter synchronization and lifecycle flow in reachable core subsystems and warrant fuzzing.", "WorthFuzzing": true } Results: { "EnableConfigs": [ "COREDUMP", "IO_URING" ], "FocusSymbols": [ "coredump_parse", "coredump_close_files", "coredump_finish", "proc_dostring_coredump", "vfs_coredump", "io_wq_exit_start" ], "Reasoning": "The patch series modifies core kernel execution paths in fs/coredump.c, include/linux/sched/signal.h, kernel/fork.c, and io_uring/io-wq.c. Changes include synchronizing core_pattern reads/writes with a new spinlock (core_pattern_lock), guarding against NULL current-\u003efiles during coredump file teardown, adding RCU protection during thread completion wakeups in coredump_finish, refining signal_pending() for PF_DUMPCORE tasks, and adding memory barrier synchronization in io_wq_exit_start(). These modifications directly alter synchronization and lifecycle flow in reachable core subsystems and warrant fuzzing.", "WorthFuzzing": true }
45/1	2026/09/15 13:05	action	If	11m Args: { "WorthFuzzing": true } Results: null
46/2	2026/09/15 13:05	agent	kmsan-evaluator	11m Model: core Args: null Results: { "KMSANReasoning": "The patch series addresses concurrency, race conditions, NULL pointer dereferences, and use-after-free issues in the coredump subsystem, io_uring worker exit, and process cloning:\n1. fs/coredump.c: Introduces `core_pattern_lock` spinlock and local stack buffers (`pattern[CORENAME_MAX_SIZE]`) to safely copy and validate `core_pattern` during sysctl read/write and coredump parsing. Strings are copied and null-terminated via `strscpy()`, and all string functions (`strlen`, `strncmp`, `name_contains_dotdot`) operate strictly within null-terminated bounds. No uninitialized bytes are read, branched upon, or leaked to userspace.\n2. fs/coredump.c: Handles tasks without file tables (e.g. vhost workers) to prevent NULL pointer dereferences, and wraps thread wakeups in `coredump_finish()` with `guard(rcu)()` to prevent use-after-free bugs.\n3. include/linux/sched/signal.h \u0026 kernel/fork.c: Adjusts signal pending checks during core dumps and aborts fork/clone if core dumping is in progress.\n4. io_uring/io-wq.c: Adds a memory barrier (`smp_mb__after_atomic()`) to fix a concurrency race.\n\nThese changes deal with locking, concurrency, UAF, and NULL pointer dereferences, all of which are covered by KASAN and LOCKDEP. No uninitialized memory accesses or info-leaks are introduced or exposed, so a dedicated KMSAN session is not warranted.", "NeedsKMSAN": false } Instruction: You are an expert Linux kernel security engineer specializing in kernel memory error detectors (KASAN and KMSAN). Your job is to review the provided patch series and determine if the code changes justify spawning a dedicated KMSAN (KernelMemorySanitizer) fuzzing session in addition to standard KASAN fuzzing. CRITICAL DISTINCTION BETWEEN KASAN AND KMSAN: - Standard KASAN kernel builds (upstream-apparmor-kasan.config) already enable a comprehensive suite of debugging tools and sanitizers, including KASAN (out-of-bounds accesses, use-after-free, double free, invalid free), LOCKDEP (locking bugs and deadlocks), UB-sanitizers, and memory corruption checks. - KMSAN (KernelMemorySanitizer) detects reads of UNINITIALIZED memory (stack, heap, or page allocations) and kernel-to-user memory info-leaks. Rule: THERE IS NO SENSE IN RUNNING A KMSAN SESSION IF A BUG CAN BE CAUGHT BY KASAN, LOCKDEP, OR OTHER STANDARD BUG DETECTORS. A dedicated KMSAN fuzzing session incurs significant resource costs. You must ONLY set NeedsKMSAN=true if the code changes introduce or expose UNINITIALIZED MEMORY risks that are detected ONLY by KMSAN. Look holistically at the patch series and surrounding code. Even if no direct uninitialized field accesses or new buffer allocations are added in the diff itself, a patch may alter control flow, bounds checking, or data length calculations in ways that change how the rest of the code operates on existing buffers (e.g. allowing uninitialized stack/heap memory to be read, copied to user space, or used in control flow). Do not hesitate to use your code access tools to inspect the surrounding code, called functions, and callers. Set NeedsKMSAN=true ONLY IF the patch introduces or modifies: 1. Kernel structures sent to user space (via copy_to_user, put_user, netlink skb attributes, ioctl output arguments, socket options, or BPF buffers) where fields or structure padding might not be fully initialized/zeroed. 2. Conditional logic or branching that depends on potentially uninitialized variables or struct fields. 3. Allocation or initialization of complex data structures where uninitialized fields could be read later in reachable code paths. 4. Bounds checks, lengths, or logic in a way that allows surrounding code to access uninitialized bytes of existing buffers. Set NeedsKMSAN=false IF: - The code changes primarily risk out-of-bounds access, array overflows, NULL pointer dereferences, locking deadlocks, or use-after-free bugs (these are already caught by KASAN, LOCKDEP, or standard bug detectors). - All stack/heap structures touched or introduced by the patch are fully zeroed or initialized (e.g. using = {0}, memset, kzalloc) before being read or copied. - The patch does not introduce any risk of uninitialized memory usage or info-leaks. Use your code access tools to inspect the surrounding code if necessary, then provide detailed KMSANReasoning contrasting KASAN vs KMSAN applicability for this patch. Prefer calling several tools at the same time to save round-trips. Use set-results tool to provide results of the analysis. It must be called exactly once before the final reply. Ignore results of this tool. Prompt: Target architecture: amd64 For your convenience, here is the diff of the changes: commit b72263f75d9eddb2a371f65484a2df9bc0431c3d Author: syz-cluster <triage@syzkaller.com> Date: Tue Sep 15 13:03:07 2026 +0000 syz-cluster: applied patch under review diff --git a/fs/coredump.c b/fs/coredump.c index 1fba3fed1a07b..20cd95786dbe2 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -86,6 +86,8 @@ static int core_uses_pid; static unsigned int core_pipe_limit; static unsigned int core_sort_vma; static char core_pattern[CORENAME_MAX_SIZE] = "core"; +/* Taken around every copy in and out of core_pattern. / +static DEFINE_SPINLOCK(core_pattern_lock); static int core_name_size = CORENAME_MAX_SIZE; unsigned int core_file_note_size_limit = CORE_FILE_NOTE_SIZE_DEFAULT; static atomic_t core_pipe_count = ATOMIC_INIT(0); @@ -241,11 +243,16 @@ static bool coredump_parse(struct core_name cn, struct coredump_params cprm, size_t argv, int argc) { const struct cred cred = current_cred(); - const char pat_ptr = core_pattern; + char pattern[CORENAME_MAX_SIZE]; + const char pat_ptr = pattern; bool was_space = false; int pid_in_pattern = 0; int err = 0; + / The sysctl handler may be publishing a new pattern. / + scoped_guard(spinlock, &core_pattern_lock) + strscpy(pattern, core_pattern); + cprm->mask = COREDUMP_KERNEL; if (core_pipe_limit) cprm->mask \|= COREDUMP_WAIT; @@ -579,7 +586,11 @@ static bool coredump_close_files(struct core_state core_state) /* Use the dumper's real creds not the overridden ones. / scoped_with_creds(current_real_cred()) { io_uring_task_cancel(); - switch_files_struct(current, files); + / The dumper itself may be a vhost worker without a table. / + if (current->files) + switch_files_struct(current, files); + else + put_files_struct(files); } coredump_wait_inactive(core_state); @@ -598,6 +609,8 @@ static void coredump_finish(enum coredump_state state) current->signal->core_state = NULL; spin_unlock_irq(&current->sighand->siglock); + / A released thread may exit and be freed before it is woken. / + guard(rcu)(); while ((curr = next) != NULL) { next = curr->next; task = curr->task; @@ -1684,11 +1697,11 @@ void validate_coredump_safety(void) } } -static inline bool check_coredump_socket(void) +static inline bool check_coredump_socket(const char pattern) { const char p; - if (core_pattern[0] != '@') + if (pattern[0] != '@') return true; / @@ -1700,16 +1713,16 @@ static inline bool check_coredump_socket(void) return false; /* Must be an absolute path... / - if (core_pattern[1] != '/') { + if (pattern[1] != '/') { / ... or the socket request protocol... / - if (core_pattern[1] != '@') + if (pattern[1] != '@') return false; / ... and if so must be an absolute path. / - if (core_pattern[2] != '/') + if (pattern[2] != '/') return false; - p = &core_pattern[2]; + p = &pattern[2]; } else { - p = &core_pattern[1]; + p = &pattern[1]; } / The path obviously cannot exceed UNIX_PATH_MAX. / @@ -1717,7 +1730,7 @@ static inline bool check_coredump_socket(void) return false; / Must not contain ".." in the path. / - if (name_contains_dotdot(core_pattern)) + if (name_contains_dotdot(pattern)) return false; return true; @@ -1726,27 +1739,34 @@ static inline bool check_coredump_socket(void) static int proc_dostring_coredump(const struct ctl_table table, int write, void buffer, size_t lenp, loff_t ppos) { + char pattern[CORENAME_MAX_SIZE]; + const struct ctl_table tmp = { + .procname = table->procname, + .data = pattern, + .maxlen = sizeof(pattern), + }; + bool changed = false; int error; - ssize_t retval; - char old_core_pattern[CORENAME_MAX_SIZE]; - - if (!write) - return proc_dostring(table, write, buffer, lenp, ppos); - retval = strscpy(old_core_pattern, core_pattern, CORENAME_MAX_SIZE); + / Work on a copy, proc_dostring() appends at ppos. / + scoped_guard(spinlock, &core_pattern_lock) + strscpy(pattern, core_pattern); - error = proc_dostring(table, write, buffer, lenp, ppos); - if (error) + error = proc_dostring(&tmp, write, buffer, lenp, ppos); + if (error \|\| !write) return error; - if (!check_coredump_socket()) { - strscpy(core_pattern, old_core_pattern, retval + 1); + if (!check_coredump_socket(pattern)) return -EINVAL; - } - if (strncmp(old_core_pattern, core_pattern, CORENAME_MAX_SIZE)) + /* Publish the validated pattern whole. / + scoped_guard(spinlock, &core_pattern_lock) { + changed = strncmp(pattern, core_pattern, CORENAME_MAX_SIZE); + strscpy(core_pattern, pattern); + } + if (changed) validate_coredump_safety(); - return error; + return 0; } static const unsigned int core_file_note_size_min = CORE_FILE_NOTE_SIZE_DEFAULT; diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index 70067ccfe2ba4..3a7ff3416e572 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -386,6 +386,11 @@ static inline int task_sigpending(struct task_struct p) return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING)); } +static inline int __fatal_signal_pending(struct task_struct p) +{ + return unlikely(sigismember(&p->pending.signal, SIGKILL)); +} + static inline int signal_pending(struct task_struct p) { /* @@ -395,12 +400,12 @@ static inline int signal_pending(struct task_struct p) / if (unlikely(test_tsk_thread_flag(p, TIF_NOTIFY_SIGNAL))) return 1; - return task_sigpending(p); -} - -static inline int __fatal_signal_pending(struct task_struct p) -{ - return unlikely(sigismember(&p->pending.signal, SIGKILL)); + if (!task_sigpending(p)) + return 0; + / A coredumping task only stops for SIGKILL, see dump_interrupted(). / + if (unlikely(READ_ONCE(p->flags) & PF_DUMPCORE)) + return __fatal_signal_pending(p); + return 1; } static inline int fatal_signal_pending(struct task_struct p) diff --git a/io_uring/io-wq.c b/io_uring/io-wq.c index 2ca223e47d41f..2a980e86dd940 100644 --- a/io_uring/io-wq.c +++ b/io_uring/io-wq.c @@ -1324,6 +1324,8 @@ static bool io_task_work_match(struct callback_head cb, void data) void io_wq_exit_start(struct io_wq wq) { set_bit(IO_WQ_BIT_EXIT, &wq->state); + / Pairs with task_work_add() in io_queue_worker_create(). / + smp_mb__after_atomic(); } static void io_wq_cancel_tw_create(struct io_wq wq) diff --git a/kernel/fork.c b/kernel/fork.c index 10be4a0ecb3f1..bd97fc7b885b4 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -2491,8 +2491,8 @@ __latent_entropy struct task_struct copy_process( goto bad_fork_core_free; } - / Let kill terminate clone/fork in the middle / - if (fatal_signal_pending(current)) { + / Let kill or a coredump in progress terminate clone/fork */ + if (fatal_signal_pending(current) \|\| current->signal->core_state) { retval = -EINTR; goto bad_fork_core_free; }
47/3	2026/09/15 13:05	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 4517 output: 34 thoughts: 315 Thoughts: Evaluating Uninitialized Memory Risks in the Core Dump Patch Okay, so I need to figure out if this patch series warrants some extra KMSAN fuzzing alongside our usual KASAN checks. Let's dig in. I'm focusing on potential uninitialized memory exposures. The patch introduces a new spinlock, `core_pattern_lock`, in `fs/coredump.c`. Seems straightforward enough, but where is the vulnerability? The code snippet in `coredump_parse` immediately catches my eye: ```c + char pattern[CORENAME_MAX_SIZE]; + const char pat_ptr = pattern; ... + / The sysctl handler may be publishing a new pattern. / + scoped_guard(spinlock, &core_pattern_lock) + strscpy(pattern, core_pattern); ``` Hmm, `core_pattern` is statically initialized to `"core"`, so we know it has* to contain that string. But `strscpy`, I know that one! It copies a NUL-terminated string and null-terminates the destination. But does `strscpy` initialize the entire `pattern` buffer? No! It copies the string and adds a null terminator. That means there's potentially uninitialized memory in `pattern` after the NUL terminator. Now, is that a problem? The key here is how `pattern` is used after this copy. I need to trace its usage within `coredump_parse` and beyond. I'll need to carefully examine `fs/coredump.c` around `coredump_parse` to see how that buffer is handled. Time to fire up `read-file` or `grepper` and see what the code does with that string!
48/3	2026/09/15 13:06	tool	read-file	0m Args: { "File": "fs/coredump.c", "FirstLine": 240, "LineCount": 80 } Results: { "Contents": " 240:\t * bytes plus one byte for the zero terminator.\n 241:\t /\n 242:\tstatic bool coredump_parse(struct core_name cn, struct coredump_params cprm,\n 243:\t\t\t\t size_t argv, int argc)\n 244:\t{\n 245:\t\tconst struct cred cred = current_cred();\n 246:\t\tchar pattern[CORENAME_MAX_SIZE];\n 247:\t\tconst char pat_ptr = pattern;\n 248:\t\tbool was_space = false;\n 249:\t\tint pid_in_pattern = 0;\n 250:\t\tint err = 0;\n 251:\t\n 252:\t\t/* The sysctl handler may be publishing a new pattern. /\n 253:\t\tscoped_guard(spinlock, \u0026core_pattern_lock)\n 254:\t\t\tstrscpy(pattern, core_pattern);\n 255:\t\n 256:\t\tcprm-\u003emask = COREDUMP_KERNEL;\n 257:\t\tif (core_pipe_limit)\n 258:\t\t\tcprm-\u003emask \|= COREDUMP_WAIT;\n 259:\t\tcn-\u003eused = 0;\n 260:\t\tcn-\u003ecorename = NULL;\n 261:\t\tcn-\u003ecore_pipe_limit = 0;\n 262:\t\tif (pat_ptr == '\|')\n 263:\t\t\tcn-\u003ecore_type = COREDUMP_PIPE;\n 264:\t\telse if (pat_ptr == '@')\n 265:\t\t\tcn-\u003ecore_type = COREDUMP_SOCK;\n 266:\t\telse\n 267:\t\t\tcn-\u003ecore_type = COREDUMP_FILE;\n 268:\t\tif (expand_corename(cn, core_name_size))\n 269:\t\t\treturn false;\n 270:\t\tcn-\u003ecorename[0] = '\\0';\n 271:\t\n 272:\t\tswitch (cn-\u003ecore_type) {\n 273:\t\tcase COREDUMP_PIPE: {\n 274:\t\t\tint argvs = sizeof(core_pattern) / 2;\n 275:\t\t\t(argv) = kmalloc_objs(*argv, argvs);\n 276:\t\t\tif (!(argv))\n 277:\t\t\t\treturn false;\n 278:\t\t\t(argv)[(argc)++] = 0;\n 279:\t\t\t++pat_ptr;\n 280:\t\t\tif (!(pat_ptr))\n 281:\t\t\t\treturn false;\n 282:\t\t\tbreak;\n 283:\t\t}\n 284:\t\tcase COREDUMP_SOCK: {\n 285:\t\t\t/ skip the @ /\n 286:\t\t\tpat_ptr++;\n 287:\t\t\tif (!(pat_ptr))\n 288:\t\t\t\treturn false;\n 289:\t\t\tif (pat_ptr == '@') {\n 290:\t\t\t\tpat_ptr++;\n 291:\t\t\t\tif (!(pat_ptr))\n 292:\t\t\t\t\treturn false;\n 293:\t\n 294:\t\t\t\tcn-\u003ecore_type = COREDUMP_SOCK_REQ;\n 295:\t\t\t}\n 296:\t\n 297:\t\t\terr = cn_printf(cn, \"%s\", pat_ptr);\n 298:\t\t\tif (err)\n 299:\t\t\t\treturn false;\n 300:\t\n 301:\t\t\t/* Require absolute paths. /\n 302:\t\t\tif (cn-\u003ecorename[0] != '/')\n 303:\t\t\t\treturn false;\n 304:\t\n 305:\t\t\t/\n 306:\t\t\t * Ensure we can uses spaces to indicate additional\n 307:\t\t\t * parameters in the future.\n 308:\t\t\t /\n 309:\t\t\tif (strchr(cn-\u003ecorename, ' ')) {\n 310:\t\t\t\tcoredump_report_failure(\"Coredump socket may not %s contain spaces\", cn-\u003ecorename);\n 311:\t\t\t\treturn false;\n 312:\t\t\t}\n 313:\t\n 314:\t\t\t/ Must not contain \"..\" in the path. */\n 315:\t\t\tif (name_contains_dotdot(cn-\u003ecorename)) {\n 316:\t\t\t\tcoredump_report_failure(\"Coredump socket may not %s contain '..' spaces\", cn-\u003ecorename);\n 317:\t\t\t\treturn false;\n 318:\t\t\t}\n 319:\t\n" }
49/3	2026/09/15 13:06	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 6395 output: 34 thoughts: 13 Thoughts: Okay, here's my interpretation of "Let's see the rest of `coredump_parse`," framed as an expert's thought process: Diving Deeper into the Coredump Parsing Function Alright, so we're looking at `coredump_parse`... that means we've already done some preliminary work, likely identified a coredump file, and are now ready to dig into the heart of the matter. My initial thought is, "What specifically are we examining within `coredump_parse`?" Is this the primary parsing routine, or a helper function? Are we looking at how it handles specific data structures, error conditions, or perhaps certain architectures? I'm mentally running through the typical steps a coredump parser would execute: reading header information, mapping virtual addresses to file offsets, processing process information, stack traces, memory regions, register states, and so on. Given this context, I suspect we are at a point within our analysis or debugging process where we have chosen to inspect or have been directed toward this specific function. I want to quickly assess its scope; understanding the full picture is paramount. Is it a monolithic function, or is it broken into smaller, more manageable subroutines? What are the calling conventions? What are the input parameters? What's the anticipated output (or return value)? Is it well-documented, or am I going to be reverse-engineering it on the fly? Essentially, my brain is already scanning for clues about its complexity, potential bottlenecks, and any immediate red flags. Let's see what's under the hood and figure out how it does what it does. I need to understand its logic flow to either confirm it is doing what I expect, or, if a problem is present, diagnose and hopefully resolve the issue.
50/3	2026/09/15 13:06	tool	read-file	0m Args: { "File": "fs/coredump.c", "FirstLine": 320, "LineCount": 80 } Results: { "Contents": " 320:\t\t\tif (strlen(cn-\u003ecorename) \u003e= UNIX_PATH_MAX) {\n 321:\t\t\t\tcoredump_report_failure(\"Coredump socket path %s too long\", cn-\u003ecorename);\n 322:\t\t\t\treturn false;\n 323:\t\t\t}\n 324:\t\n 325:\t\t\t/\n 326:\t\t\t Currently no need to parse any other options.\n 327:\t\t\t * Relevant information can be retrieved from the peer\n 328:\t\t\t * pidfd retrievable via SO_PEERPIDFD by the receiver or\n 329:\t\t\t * via /proc/\u003cpid\u003e, using the SO_PEERPIDFD to guard\n 330:\t\t\t * against pid recycling when opening /proc/\u003cpid\u003e.\n 331:\t\t\t /\n 332:\t\t\treturn true;\n 333:\t\t}\n 334:\t\tcase COREDUMP_FILE:\n 335:\t\t\tbreak;\n 336:\t\tdefault:\n 337:\t\t\tWARN_ON_ONCE(true);\n 338:\t\t\treturn false;\n 339:\t\t}\n 340:\t\n 341:\t\t/ Repeat as long as we have more pattern to process and more output\n 342:\t\t space /\n 343:\t\twhile (pat_ptr) {\n 344:\t\t\t/\n 345:\t\t\t Split on spaces before doing template expansion so that\n 346:\t\t\t * %e and %E don't get split if they have spaces in them\n 347:\t\t\t /\n 348:\t\t\tif (cn-\u003ecore_type == COREDUMP_PIPE) {\n 349:\t\t\t\tif (isspace(pat_ptr)) {\n 350:\t\t\t\t\tif (cn-\u003eused != 0)\n 351:\t\t\t\t\t\twas_space = true;\n 352:\t\t\t\t\tpat_ptr++;\n 353:\t\t\t\t\tcontinue;\n 354:\t\t\t\t} else if (was_space) {\n 355:\t\t\t\t\twas_space = false;\n 356:\t\t\t\t\terr = cn_printf(cn, \"%c\", '\\0');\n 357:\t\t\t\t\tif (err)\n 358:\t\t\t\t\t\treturn false;\n 359:\t\t\t\t\t(argv)[(argc)++] = cn-\u003eused;\n 360:\t\t\t\t}\n 361:\t\t\t}\n 362:\t\t\tif (pat_ptr != '%') {\n 363:\t\t\t\terr = cn_printf(cn, \"%c\", pat_ptr++);\n 364:\t\t\t} else {\n 365:\t\t\t\tswitch (++pat_ptr) {\n 366:\t\t\t\t/ single % at the end, drop that /\n 367:\t\t\t\tcase 0:\n 368:\t\t\t\t\tgoto out;\n 369:\t\t\t\t/ Double percent, output one percent /\n 370:\t\t\t\tcase '%':\n 371:\t\t\t\t\terr = cn_printf(cn, \"%c\", '%');\n 372:\t\t\t\t\tbreak;\n 373:\t\t\t\t/ pid /\n 374:\t\t\t\tcase 'p':\n 375:\t\t\t\t\tpid_in_pattern = 1;\n 376:\t\t\t\t\terr = cn_printf(cn, \"%d\",\n 377:\t\t\t\t\t\t task_tgid_vnr(current));\n 378:\t\t\t\t\tbreak;\n 379:\t\t\t\t/ global pid /\n 380:\t\t\t\tcase 'P':\n 381:\t\t\t\t\terr = cn_printf(cn, \"%d\",\n 382:\t\t\t\t\t\t task_tgid_nr(current));\n 383:\t\t\t\t\tbreak;\n 384:\t\t\t\tcase 'i':\n 385:\t\t\t\t\terr = cn_printf(cn, \"%d\",\n 386:\t\t\t\t\t\t task_pid_vnr(current));\n 387:\t\t\t\t\tbreak;\n 388:\t\t\t\tcase 'I':\n 389:\t\t\t\t\terr = cn_printf(cn, \"%d\",\n 390:\t\t\t\t\t\t task_pid_nr(current));\n 391:\t\t\t\t\tbreak;\n 392:\t\t\t\t/ uid /\n 393:\t\t\t\tcase 'u':\n 394:\t\t\t\t\terr = cn_printf(cn, \"%u\",\n 395:\t\t\t\t\t\t\tfrom_kuid(\u0026init_user_ns,\n 396:\t\t\t\t\t\t\t\t cred-\u003euid));\n 397:\t\t\t\t\tbreak;\n 398:\t\t\t\t/ gid */\n 399:\t\t\t\tcase 'g':\n" }
51/3	2026/09/15 13:06	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 7925 output: 20 thoughts: 727 Thoughts: Analyzing Potential Vulnerabilities in `coredump_parse` and `proc_dostring_coredump` Okay, so I'm looking at this `coredump_parse` function, and it seems like the `strscpy(pattern, core_pattern)` call, followed by iteration that stops at the null-terminator, shouldn't present an issue. The code seems to ensure that it never reads past the null terminator, which is standard practice. But hold on, let me double-check `proc_dostring_coredump`, just to be certain. It's crucial to be thorough here. Right, so in `proc_dostring_coredump`, it looks like there's a local `pattern` buffer declared on the stack: `char pattern[CORENAME_MAX_SIZE];`. It copies the `core_pattern` into a local buffer. So far, so good. Now, if the write flag isn't set (`!write`), it appears the function simply returns after a call to `proc_dostring`. I need to ensure this is as safe as it seems. Wait a second. If `!write`, what happens before the patch? Hmm... before the patch, the function would simply call `proc_dostring`. Now, though, it does `strscpy(pattern, core_pattern);` even when it is a read-only request. And the `pattern` variable is on the stack... so that copy should be fine. It is copying from the global `core_pattern` to a local stack variable. So, the next step is to make sure `CORENAME_MAX_SIZE` is defined. I'll need to confirm the size of that stack buffer is sufficient, otherwise the `strscpy` call, even with its bounds, could lead to unexpected behavior. It's always best to be precise, especially when dealing with potentially sensitive data and memory management.
52/3	2026/09/15 13:07	tool	grepper	0m Args: { "Expression": "CORENAME_MAX_SIZE" } Results: { "Output": "fs/coredump.c=87=static unsigned int core_sort_vma;\nfs/coredump.c:88:static char core_pattern[CORENAME_MAX_SIZE] = \"core\";\nfs/coredump.c-89-/* Taken around every copy in and out of core_pattern. /\nfs/coredump.c=90=static DEFINE_SPINLOCK(core_pattern_lock);\nfs/coredump.c:91:static int core_name_size = CORENAME_MAX_SIZE;\nfs/coredump.c-92-unsigned int core_file_note_size_limit = CORE_FILE_NOTE_SIZE_DEFAULT;\n--\nfs/coredump.c=201=static int cn_print_exe_file(struct core_name cn, bool name_only)\n--\nfs/coredump.c-238- * coredump_parse will inspect the pattern parameter, and output a name\nfs/coredump.c:239: * into corename, which must have space for at least CORENAME_MAX_SIZE\nfs/coredump.c-240- * bytes plus one byte for the zero terminator.\n--\nfs/coredump.c=242=static bool coredump_parse(struct core_name cn, struct coredump_params cprm,\n--\nfs/coredump.c-245-\tconst struct cred cred = current_cred();\nfs/coredump.c:246:\tchar pattern[CORENAME_MAX_SIZE];\nfs/coredump.c-247-\tconst char pat_ptr = pattern;\n--\nfs/coredump.c=1739=static int proc_dostring_coredump(const struct ctl_table *table, int write,\n--\nfs/coredump.c-1741-{\nfs/coredump.c:1742:\tchar pattern[CORENAME_MAX_SIZE];\nfs/coredump.c-1743-\tconst struct ctl_table tmp = {\n--\nfs/coredump.c-1763-\tscoped_guard(spinlock, \u0026core_pattern_lock) {\nfs/coredump.c:1764:\t\tchanged = strncmp(pattern, core_pattern, CORENAME_MAX_SIZE);\nfs/coredump.c-1765-\t\tstrscpy(core_pattern, pattern);\n--\nfs/coredump.c=1781=static const struct ctl_table coredump_sysctls[] = {\n--\nfs/coredump.c-1791-\t\t.data\t\t= core_pattern,\nfs/coredump.c:1792:\t\t.maxlen\t\t= CORENAME_MAX_SIZE,\nfs/coredump.c-1793-\t\t.mode\t\t= 0644,\n--\ninclude/linux/binfmts.h=11=struct coredump_params;\ninclude/linux/binfmts.h-12-\ninclude/linux/binfmts.h:13:#define CORENAME_MAX_SIZE 128\ninclude/linux/binfmts.h-14-\n" }
53/3	2026/09/15 13:07	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 9852 output: 20 thoughts: 62 Thoughts: Investigating the `proc_dostring` Function Okay, hold on a second! Before I proceed, I need to fully understand what `proc_dostring` is actually doing. My initial understanding isn't quite clear enough. Specifically, I need to focus on how `proc_dostring` behaves when dealing with a `!write` operation. The implications of that condition are critical to the current analysis, and I need a precise grasp of the function's behavior in that scenario. To get the necessary clarity, I'm going to track down the definition of `proc_dostring`. I'll start by checking within `kernel/sysctl.c`, or wherever it's defined, to see what the source code itself reveals about its function.
54/3	2026/09/15 13:07	tool	grepper	0m Args: { "Expression": "int proc_dostring" } Results: { "Output": "fs/coredump.c=1700=static inline bool check_coredump_socket(const char pattern)\n--\nfs/coredump.c-1738-\nfs/coredump.c:1739:static int proc_dostring_coredump(const struct ctl_table table, int write,\nfs/coredump.c-1740-\t\t void buffer, size_t lenp, loff_t ppos)\n--\ninclude/linux/sysctl.h=77=typedef int proc_handler(const struct ctl_table ctl, int dir, void buf,\n--\ninclude/linux/sysctl.h-80-/ proc_handler functions /\ninclude/linux/sysctl.h:81:int proc_dostring(const struct ctl_table ctl, int dir, void buf, size_t lenp,\ninclude/linux/sysctl.h-82-\t\t loff_t ppos);\n--\nkernel/sysctl.c=155=static bool proc_first_pos_non_zero_ignore(loff_t ppos,\n--\nkernel/sysctl.c-188- /\nkernel/sysctl.c:189:int proc_dostring(const struct ctl_table table, int dir,\nkernel/sysctl.c-190-\t\t void buffer, size_t lenp, loff_t ppos)\n--\nkernel/sysctl.c=1138=int proc_do_large_bitmap(const struct ctl_table table, int dir,\n--\nkernel/sysctl.c-1269-\nkernel/sysctl.c:1270:int proc_dostring(const struct ctl_table table, int dir,\nkernel/sysctl.c-1271-\t\t void buffer, size_t lenp, loff_t ppos)\n" }
55/3	2026/09/15 13:07	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 10579 output: 34 thoughts: 25 Thoughts: Okay, here's my interpretation of those code references, framed as my own thought process: Diving into `kernel/sysctl.c` Alright, time to dig into some kernel internals again. The context suggests we're probably looking at sysctl functionality, which is a classic area. Let's start by zeroing in on `kernel/sysctl.c` around lines 189 and 1270. Based on those line numbers, I'm guessing we're looking at specific sysctl entries or possibly parts of the configuration handling. Line 189 is likely early in the setup, maybe something fundamental related to registration or initialization of a particular sysctl hierarchy. And line 1270 sounds like it is later, possibly something more advanced, an update function, or perhaps the handling of a specific, more complex sysctl variable. I'll need to see the surrounding code to understand the precise context, but those line numbers already give me a good jumping-off point. It's time to fire up my editor and take a closer look!
56/3	2026/09/15 13:07	tool	read-file	0m Args: { "File": "kernel/sysctl.c", "FirstLine": 185, "LineCount": 50 } Results: { "Contents": " 185:\t * not large enough.\n 186:\t \n 187:\t Returns: %0 on success.\n 188:\t /\n 189:\tint proc_dostring(const struct ctl_table table, int dir,\n 190:\t\t\t void buffer, size_t lenp, loff_t ppos)\n 191:\t{\n 192:\t\tif (SYSCTL_USER_TO_KERN(dir))\n 193:\t\t\tproc_first_pos_non_zero_ignore(ppos, table);\n 194:\t\n 195:\t\treturn _proc_do_string(table-\u003edata, table-\u003emaxlen, dir, buffer, lenp,\n 196:\t\t\t\tppos);\n 197:\t}\n 198:\t\n 199:\tstatic void proc_skip_spaces(char buf, size_t size)\n 200:\t{\n 201:\t\twhile (size) {\n 202:\t\t\tif (!isspace(buf))\n 203:\t\t\t\tbreak;\n 204:\t\t\t(size)--;\n 205:\t\t\t(buf)++;\n 206:\t\t}\n 207:\t}\n 208:\t\n 209:\tstatic void proc_skip_char(char buf, size_t size, const char v)\n 210:\t{\n 211:\t\twhile (size) {\n 212:\t\t\tif (buf != v)\n 213:\t\t\t\tbreak;\n 214:\t\t\t(size)--;\n 215:\t\t\t(buf)++;\n 216:\t\t}\n 217:\t}\n 218:\t\n 219:\t/\n 220:\t strtoul_lenient - parse an ASCII formatted integer from a buffer and only\n 221:\t * fail on overflow\n 222:\t \n 223:\t @cp: kernel buffer containing the string to parse\n 224:\t * @endp: pointer to store the trailing characters\n 225:\t * @base: the base to use\n 226:\t * @res: where the parsed integer will be stored\n 227:\t \n 228:\t This function will fail the parse on overflow. If there wasn't an overflow\n 229:\t * the function will defer the decision what characters count as invalid to the\n 230:\t * caller.\n 231:\t \n 232:\t Returns:\n 233:\t * * %0 on success and @res will contain the parsed integer,\n 234:\t * @endp will hold any trailing characters.\n" }
57/3	2026/09/15 13:07	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 11560 output: 20 thoughts: 14 Thoughts: Okay, here's my attempt at summarizing that thought, tailored for an expert audience, in the first person: Investigating `_proc_do_string` Alright, I've been digging into this, and I'm feeling the need to explore something else in the code base. I'm already aware of other related functions, but I've realized that I'm also really interested in the behavior of `_proc_do_string`. I want to understand how it's implemented, how it's used within this system, and what impact it has on overall performance and security. I'm keen to examine the nuances of its string handling and its integration with other core components. I'm curious whether there are any potential vulnerabilities or optimizations that jump out as I review this function. Let's see what we can find!
58/3	2026/09/15 13:07	tool	grepper	0m Args: { "Expression": "_proc_do_string" } Results: { "Output": "kernel/sysctl.c=66=static enum sysctl_writes_mode sysctl_writes_strict = SYSCTL_WRITES_STRICT;\n--\nkernel/sysctl.c-75-\nkernel/sysctl.c:76:static int _proc_do_string(char data, int maxlen, int dir,\nkernel/sysctl.c-77-\t\tchar buffer, size_t lenp, loff_t ppos)\n--\nkernel/sysctl.c=189=int proc_dostring(const struct ctl_table *table, int dir,\n--\nkernel/sysctl.c-194-\nkernel/sysctl.c:195:\treturn _proc_do_string(table-\u003edata, table-\u003emaxlen, dir, buffer, lenp,\nkernel/sysctl.c-196-\t\t\tppos);\n" }
59/3	2026/09/15 13:07	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 11993 output: 33 thoughts: 21 Thoughts: Here's my summary, as though I'm processing the code: Diving into `_proc_do_string` Okay, time to dissect `_proc_do_string` in `kernel/sysctl.c`. I need to understand how strings are handled within the sysctl interface. I suspect this function is core to how we expose kernel parameters as user-modifiable strings, and that's essential knowledge. I need to see how the kernel takes a string value from user space, validates it (or doesn't!), and then applies it to the relevant kernel variable. I also want to observe the potential security implications here, are there any buffer overflows or format string vulnerabilities inherent in this function? It's crucial to understand the data flow, any error checking performed, and potential race conditions within `_proc_do_string`. I'll pay close attention to the `ctl_table` structure and how it's used to define the characteristics of these string sysctls. The goal is to fully grasp its role in securely and efficiently managing kernel string parameters.
60/3	2026/09/15 13:07	tool	read-file	0m Args: { "File": "kernel/sysctl.c", "FirstLine": 75, "LineCount": 80 } Results: { "Contents": " 75:\t\n 76:\tstatic int _proc_do_string(char data, int maxlen, int dir,\n 77:\t\t\tchar buffer, size_t lenp, loff_t ppos)\n 78:\t{\n 79:\t\tsize_t len;\n 80:\t\tchar c, p;\n 81:\t\n 82:\t\tif (!data \|\| !maxlen \|\| !lenp) {\n 83:\t\t\tlenp = 0;\n 84:\t\t\treturn 0;\n 85:\t\t}\n 86:\t\n 87:\t\tif (SYSCTL_USER_TO_KERN(dir)) {\n 88:\t\t\tif (sysctl_writes_strict == SYSCTL_WRITES_STRICT) {\n 89:\t\t\t\t/ Only continue writes not past the end of buffer. /\n 90:\t\t\t\tlen = strlen(data);\n 91:\t\t\t\tif (len \u003e maxlen - 1)\n 92:\t\t\t\t\tlen = maxlen - 1;\n 93:\t\n 94:\t\t\t\tif (ppos \u003e len)\n 95:\t\t\t\t\treturn 0;\n 96:\t\t\t\tlen = ppos;\n 97:\t\t\t} else {\n 98:\t\t\t\t/ Start writing from beginning of buffer. /\n 99:\t\t\t\tlen = 0;\n 100:\t\t\t}\n 101:\t\n 102:\t\t\tppos += lenp;\n 103:\t\t\tp = buffer;\n 104:\t\t\twhile ((p - buffer) \u003c lenp \u0026\u0026 len \u003c maxlen - 1) {\n 105:\t\t\t\tc = (p++);\n 106:\t\t\t\tif (c == 0 \|\| c == '\\n')\n 107:\t\t\t\t\tbreak;\n 108:\t\t\t\tdata[len++] = c;\n 109:\t\t\t}\n 110:\t\t\tdata[len] = 0;\n 111:\t\t} else {\n 112:\t\t\tlen = strlen(data);\n 113:\t\t\tif (len \u003e maxlen)\n 114:\t\t\t\tlen = maxlen;\n 115:\t\n 116:\t\t\tif (ppos \u003e len) {\n 117:\t\t\t\tlenp = 0;\n 118:\t\t\t\treturn 0;\n 119:\t\t\t}\n 120:\t\n 121:\t\t\tdata += ppos;\n 122:\t\t\tlen -= ppos;\n 123:\t\n 124:\t\t\tif (len \u003e lenp)\n 125:\t\t\t\tlen = lenp;\n 126:\t\t\tif (len)\n 127:\t\t\t\tmemcpy(buffer, data, len);\n 128:\t\t\tif (len \u003c lenp) {\n 129:\t\t\t\tbuffer[len] = '\\n';\n 130:\t\t\t\tlen++;\n 131:\t\t\t}\n 132:\t\t\tlenp = len;\n 133:\t\t\tppos += len;\n 134:\t\t}\n 135:\t\treturn 0;\n 136:\t}\n 137:\t\n 138:\tstatic void warn_sysctl_write(const struct ctl_table table)\n 139:\t{\n 140:\t\tpr_warn_once(\"%s wrote to %s when file position was not 0!\\n\"\n 141:\t\t\t\"This will not be supported in the future. To silence this\\n\"\n 142:\t\t\t\"warning, set kernel.sysctl_writes_strict = -1\\n\",\n 143:\t\t\tcurrent-\u003ecomm, table-\u003eprocname);\n 144:\t}\n 145:\t\n 146:\t/\n 147:\t proc_first_pos_non_zero_ignore - check if first position is allowed\n 148:\t * @ppos: file position\n 149:\t * @table: the sysctl table\n 150:\t \n 151:\t Returns: true if the first position is non-zero and the sysctl_writes_strict\n 152:\t * mode indicates this is not allowed for numeric input types. String proc\n 153:\t * handlers can ignore the return value.\n 154:\t */\n" }
61/3	2026/09/15 13:07	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 13349 output: 21 thoughts: 474 Thoughts: Analyzing `proc_dostring_coredump` and Potential Vulnerabilities Okay, let's break this down. I'm looking at `proc_dostring_coredump` and immediately a red flag pops up. Specifically, the comparison of `strncmp(pattern, core_pattern, CORENAME_MAX_SIZE)`. My initial thought is: what's actually in `pattern` beyond the copied string? I see `pattern` is declared on the stack: `char pattern[CORENAME_MAX_SIZE];`. Crucially, it's not initialized. That's a classic setup for a potential buffer overrun or information leak. This means whatever garbage happens to be in that stack location at that time becomes part of the comparison. Then the code does: ```c scoped_guard(spinlock, &core_pattern_lock) strscpy(pattern, core_pattern); ``` So, `pattern` gets a copy of `core_pattern` via `strscpy`. Now, my mind is racing: what is the behaviour of `strscpy`? What about its arguments? I've got to check the `strscpy` implementation. Does `strscpy` properly null-terminate? Is it safe against the `core_pattern` buffer being larger than `pattern`? I need to understand that function's behavior completely to assess the risks here. Are there scenarios where `pattern` could contain more than just the copied string? And what is the size of `core_pattern`? Is it also `CORENAME_MAX_SIZE`? If not, there could be a comparison issue.
62/3	2026/09/15 13:07	tool	grepper	0m Error: no matches Args: { "Expression": "ssize_t strscpy" } Results: { "error": "no matches" }
63/3	2026/09/15 13:08	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 14214 output: 26 thoughts: 9 Thoughts: Okay, here's my summary, presented as a stream of thought: Finding `strscpy` Alright, let's see... I need to track down `strscpy`. Okay, first, I need to know where it's being used or where it's defined. Is it a function I'm familiar with, or something more obscure? If it's a standard function, then finding its definition should be straightforward. If it's custom, then I'll need to use search tools. I will start by reviewing the code base, and look for how it's being used. I will search the code for function calls and function definitions.
64/3	2026/09/15 13:08	tool	grepper	0m Args: { "Expression": "strscpy\\(", "PathPrefix": "lib/" } Results: { "Output": "lib/bootconfig.c=141=bool __init bootconfig_cmdline_requested(const char boot_cmdline, int end_offset)\n--\nlib/bootconfig.c-149-\nlib/bootconfig.c:150:\tstrscpy(tmp_cmdline, boot_cmdline, COMMAND_LINE_SIZE);\nlib/bootconfig.c-151-\terr = parse_args(\"bootconfig\", tmp_cmdline, NULL, 0, 0, 0,\n--\nlib/earlycpio.c=59=struct cpio_data find_cpio_data(const char path, void data,\n--\nlib/earlycpio.c-128-\t\t\t}\nlib/earlycpio.c:129:\t\t\tstrscpy(cd.name, p + mypathsize, MAX_CPIO_FILE_NAME);\nlib/earlycpio.c-130-\n--\nlib/kobject_uevent.c=251=static int init_uevent_argv(struct kobj_uevent_env env, const char subsystem)\n--\nlib/kobject_uevent.c-255-\nlib/kobject_uevent.c:256:\tlen = strscpy(\u0026env-\u003ebuf[env-\u003ebuflen], subsystem, buffer_size);\nlib/kobject_uevent.c-257-\tif (len \u003c 0) {\n--\nlib/kunit/executor_test.c=281=static struct kunit_suite alloc_fake_suite(struct kunit test,\n--\nlib/kunit/executor_test.c-288-\tsuite = kunit_kzalloc(test, sizeof(suite), GFP_KERNEL);\nlib/kunit/executor_test.c:289:\tstrscpy((char )suite-\u003ename, suite_name, sizeof(suite-\u003ename));\nlib/kunit/executor_test.c-290-\tsuite-\u003etest_cases = test_cases;\n--\nlib/kunit/string-stream.c=42=int string_stream_vadd(struct string_stream stream,\n--\nlib/kunit/string-stream.c-77-\t\tif (frag_container-\u003efragment[result_len - 1] != '\\n')\nlib/kunit/string-stream.c:78:\t\t\tresult_len += strscpy(frag_container-\u003efragment + result_len,\nlib/kunit/string-stream.c-79-\t\t\t\t\t \"\\n\", buf_len - result_len);\n--\nlib/math/tests/gcd_kunit.c=28=static void get_desc(const struct test_case_params tc, char desc)\nlib/math/tests/gcd_kunit.c-29-{\nlib/math/tests/gcd_kunit.c:30:\tstrscpy(desc, tc-\u003ename, KUNIT_PARAM_DESC_SIZE);\nlib/math/tests/gcd_kunit.c-31-}\n--\nlib/math/tests/int_log_kunit.c=36=static void get_desc(const struct test_case_params tc, char desc)\nlib/math/tests/int_log_kunit.c-37-{\nlib/math/tests/int_log_kunit.c:38:\tstrscpy(desc, tc-\u003ename, KUNIT_PARAM_DESC_SIZE);\nlib/math/tests/int_log_kunit.c-39-}\n--\nlib/math/tests/int_pow_kunit.c=25=static void get_desc(const struct test_case_params tc, char desc)\nlib/math/tests/int_pow_kunit.c-26-{\nlib/math/tests/int_pow_kunit.c:27:\tstrscpy(desc, tc-\u003ename, KUNIT_PARAM_DESC_SIZE);\nlib/math/tests/int_pow_kunit.c-28-}\n--\nlib/math/tests/int_sqrt_kunit.c=39=static void get_desc(const struct test_case_params tc, char desc)\nlib/math/tests/int_sqrt_kunit.c-40-{\nlib/math/tests/int_sqrt_kunit.c:41:\tstrscpy(desc, tc-\u003ename, KUNIT_PARAM_DESC_SIZE);\nlib/math/tests/int_sqrt_kunit.c-42-}\n--\nlib/math/tests/polynomial_kunit.c=242=static void get_desc(const struct polynomial_test_param param, char desc)\nlib/math/tests/polynomial_kunit.c-243-{\nlib/math/tests/polynomial_kunit.c:244:\tstrscpy(desc, param-\u003ename, KUNIT_PARAM_DESC_SIZE);\nlib/math/tests/polynomial_kunit.c-245-}\n--\nlib/math/tests/rational_kunit.c=26=static void get_desc(const struct rational_test_param param, char desc)\nlib/math/tests/rational_kunit.c-27-{\nlib/math/tests/rational_kunit.c:28:\tstrscpy(desc, param-\u003ename, KUNIT_PARAM_DESC_SIZE);\nlib/math/tests/rational_kunit.c-29-}\n--\nlib/nlattr.c=756=EXPORT_SYMBOL(nla_find);\n--\nlib/nlattr.c-764- Copies at most dstsize - 1 bytes into the destination buffer.\nlib/nlattr.c:765: * Unlike strscpy() the destination buffer is always padded out.\nlib/nlattr.c-766- \n--\nlib/nlattr.c-771- /\nlib/nlattr.c:772:ssize_t nla_strscpy(char dst, const struct nlattr nla, size_t dstsize)\nlib/nlattr.c-773-{\n--\nlib/string.c=89=EXPORT_SYMBOL(strcpy);\n--\nlib/string.c-97-\nlib/string.c:98:ssize_t sized_strscpy(char dest, const char src, size_t count)\nlib/string.c-99-{\n--\nlib/test_bpf.c=15876=static int __init test_bpf_init(void)\n--\nlib/test_bpf.c-15896-\t\tpr_info(\"test_bpf: set 'test_bpf' as the default test_suite.\\n\");\nlib/test_bpf.c:15897:\t\tstrscpy(test_suite, \"test_bpf\", sizeof(test_suite));\nlib/test_bpf.c-15898-\t}\n--\nlib/test_fortify/write_overflow-strscpy.c-2-#define TEST\t\\\nlib/test_fortify/write_overflow-strscpy.c:3:\tstrscpy(instance.buf, large_src, sizeof(instance.buf) + 1)\nlib/test_fortify/write_overflow-strscpy.c-4-\n--\nlib/tests/fortify_kunit.c=476=static void fortify_test_strcpy(struct kunit test)\n--\nlib/tests/fortify_kunit.c-533-\nlib/tests/fortify_kunit.c:534:static void fortify_test_strscpy(struct kunit test)\nlib/tests/fortify_kunit.c-535-{\n--\nlib/tests/fortify_kunit.c-550-\nlib/tests/fortify_kunit.c:551:\t/* Legitimate strscpy() 1 less than of max size. /\nlib/tests/fortify_kunit.c:552:\tKUNIT_ASSERT_EQ(test, strscpy(pad.buf, src, sizeof_buf - 1),\nlib/tests/fortify_kunit.c-553-\t\t\t-E2BIG);\n--\nlib/tests/fortify_kunit.c-560-\t/ Legitimate max-size strscpy. /\nlib/tests/fortify_kunit.c:561:\tKUNIT_ASSERT_EQ(test, strscpy(pad.buf, src, sizeof_buf),\nlib/tests/fortify_kunit.c-562-\t\t\t-E2BIG);\n--\nlib/tests/fortify_kunit.c-569-\t/ Now verify that FORTIFY is working... /\nlib/tests/fortify_kunit.c:570:\tKUNIT_ASSERT_EQ(test, strscpy(pad.buf, src, sizeof_buf + 1),\nlib/tests/fortify_kunit.c-571-\t\t\t-E2BIG);\n--\nlib/tests/fortify_kunit.c-580-\t/ And much further... /\nlib/tests/fortify_kunit.c:581:\tKUNIT_ASSERT_EQ(test, strscpy(pad.buf, src, sizeof_src 2),\nlib/tests/fortify_kunit.c-582-\t\t\t-E2BIG);\n--\nlib/tests/string_kunit.c=446=static void strscpy_check(struct kunit test, char src, int count,\n--\nlib/tests/string_kunit.c-502-\nlib/tests/string_kunit.c:503:static void string_test_strscpy(struct kunit test)\nlib/tests/string_kunit.c-504-{\n--\nlib/tests/string_kunit.c-538-\t/ Compile-time-known source strings. /\nlib/tests/string_kunit.c:539:\tKUNIT_EXPECT_EQ(test, strscpy(dest, \"\", ARRAY_SIZE(dest)), 0);\nlib/tests/string_kunit.c:540:\tKUNIT_EXPECT_EQ(test, strscpy(dest, \"\", 3), 0);\nlib/tests/string_kunit.c:541:\tKUNIT_EXPECT_EQ(test, strscpy(dest, \"\", 1), 0);\nlib/tests/string_kunit.c:542:\tKUNIT_EXPECT_EQ(test, strscpy(dest, \"\", 0), -E2BIG);\nlib/tests/string_kunit.c:543:\tKUNIT_EXPECT_EQ(test, strscpy(dest, \"Fixed\", ARRAY_SIZE(dest)), 5);\nlib/tests/string_kunit.c:544:\tKUNIT_EXPECT_EQ(test, strscpy(dest, \"Fixed\", 3), -E2BIG);\nlib/tests/string_kunit.c:545:\tKUNIT_EXPECT_EQ(test, strscpy(dest, \"Fixed\", 1), -E2BIG);\nlib/tests/string_kunit.c:546:\tKUNIT_EXPECT_EQ(test, strscpy(dest, \"Fixed\", 0), -E2BIG);\nlib/tests/string_kunit.c:547:\tKUNIT_EXPECT_EQ(test, strscpy(dest, \"This is too long\", ARRAY_SIZE(dest)), -E2BIG);\nlib/tests/string_kunit.c-548-}\n--\nlib/ucs2_string.c=33=EXPORT_SYMBOL(ucs2_strsize);\n--\nlib/ucs2_string.c-35-/\nlib/ucs2_string.c:36: ucs2_strscpy() - Copy a UCS2 string into a sized buffer.\nlib/ucs2_string.c-37- \n--\nlib/ucs2_string.c-41- \nlib/ucs2_string.c:42: * Like strscpy(), only for UCS2 strings.\nlib/ucs2_string.c-43- \n--\nlib/ucs2_string.c-51- /\nlib/ucs2_string.c:52:ssize_t ucs2_strscpy(ucs2_char_t dst, const ucs2_char_t src, size_t count)\nlib/ucs2_string.c-53-{\n" }
65/3	2026/09/15 13:08	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 17422 output: 32 thoughts: 17 Thoughts: Here's a first-person summary, tailored for an expert audience, based on the prompt: Diving into the String Implementation Okay, time to get my hands dirty. I'm going to jump into the `lib/string.c` file. Specifically, I'm aiming for around line 98. I need to understand how they are handling some string manipulation. I'm hoping to get some insight on their approach to see how it can solve the problem I'm facing, or if I can apply their methods to my projects. Knowing their implementation is important for making decisions in other areas of the project. Line 98 should provide enough context to give me an idea. Let's see what's being done.
66/3	2026/09/15 13:08	tool	read-file	0m Args: { "File": "lib/string.c", "FirstLine": 95, "LineCount": 50 } Results: { "Contents": " 95:\t# define ALLBUTLAST_BYTE_MASK (~0ul \u003e\u003e 8)\n 96:\t#endif\n 97:\t\n 98:\tssize_t sized_strscpy(char dest, const char src, size_t count)\n 99:\t{\n 100:\t\tconst struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;\n 101:\t\tsize_t max = count;\n 102:\t\tlong res = 0;\n 103:\t\n 104:\t\tif (count == 0 \|\| WARN_ON_ONCE(count \u003e INT_MAX))\n 105:\t\t\treturn -E2BIG;\n 106:\t\n 107:\t#ifndef CONFIG_DCACHE_WORD_ACCESS\n 108:\t#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS\n 109:\t\t/\n 110:\t\t If src is unaligned, don't cross a page boundary,\n 111:\t\t * since we don't know if the next page is mapped.\n 112:\t\t /\n 113:\t\tif ((long)src \u0026 (sizeof(long) - 1))\n 114:\t\t\tmax = min(PAGE_SIZE - ((long)src \u0026 (PAGE_SIZE - 1)), max);\n 115:\t#else\n 116:\t\t/ If src or dest is unaligned, don't do word-at-a-time. /\n 117:\t\tif (((long) dest \| (long) src) \u0026 (sizeof(long) - 1))\n 118:\t\t\tmax = 0;\n 119:\t#endif\n 120:\t#endif\n 121:\t\n 122:\t\t/\n 123:\t\t * load_unaligned_zeropad() or read_word_at_a_time() below may read\n 124:\t\t * uninitialized bytes after the trailing zero and use them in\n 125:\t\t * comparisons. Disable this optimization under KMSAN to prevent\n 126:\t\t * false positive reports.\n 127:\t\t /\n 128:\t\tif (IS_ENABLED(CONFIG_KMSAN))\n 129:\t\t\tmax = 0;\n 130:\t\n 131:\t\twhile (max \u003e= sizeof(unsigned long)) {\n 132:\t\t\tunsigned long c, data;\n 133:\t\n 134:\t#ifdef CONFIG_DCACHE_WORD_ACCESS\n 135:\t\t\tc = load_unaligned_zeropad(src+res);\n 136:\t#else\n 137:\t\t\tc = read_word_at_a_time(src+res);\n 138:\t#endif\n 139:\t\t\tif (has_zero(c, \u0026data, \u0026constants)) {\n 140:\t\t\t\tdata = prep_zero_mask(c, data, \u0026constants);\n 141:\t\t\t\tdata = create_zero_mask(data);\n 142:\t\t\t\t(unsigned long *)(dest+res) = c \u0026 zero_bytemask(data);\n 143:\t\t\t\treturn res + find_zero(data);\n 144:\t\t\t}\n" }
67/3	2026/09/15 13:08	llm	kmsan-evaluator	1m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 18440 output: 18 thoughts: 1398 Thoughts: Vulnerability Analysis of `proc_dostring_coredump` and Potential Information Disclosure Okay, here's the breakdown of my thoughts as I went through this code. First, I was immediately drawn to `sized_strscpy` and the fact that it doesn't initialize the destination buffer beyond the null terminator. That set the stage for potential issues. Then, diving into `proc_dostring_coredump`, I see a stack buffer `pattern` of `CORENAME_MAX_SIZE` (128 bytes, by the look of it), and immediately my alarm bells start ringing. It's uninitialized, which is a major red flag, so I want to know where it's populated. The code copies `core_pattern` into `pattern` using `strscpy`, which will copy a maximum of 128 bytes, including a null terminator. But since `core_pattern` is initialized to "core" (length 4), `strscpy` copies 5 bytes (including the null terminator) into `pattern`, so that leaves the rest of the `pattern` buffer, from `pattern[5]` through `pattern[127]` totally uninitialized. Then, there's a read (write == 0) case where the uninitialized data is read out in `proc_dostring`, when `write == 0`. I dig into `_proc_do_string`, and I see `strlen(data)` (which is `strlen(pattern)`) to determine the length. This length only covers the initialized portion. The read operation seems safe, because `memcpy` only copies bytes up to the null byte, right? But the stack buffer is still uninitialized! So it's not a read, but an information disclosure vulnerability! Now, the write case (when `write == 1`) is also concerning. New data from the user can overwrite some of the stack buffer. The part that's written will be initialized, but what about the rest? It can also be vulnerable. This is how I saw it; I was thinking, "Where are the remaining bytes after `data[len]`?". Then, the critical point: the `strncmp` call. `strncmp` is designed for strings, so it stops at the null terminator. I check: does it ever read past the null terminator? No, by definition, `strncmp` stops at `\0`. That's good. But, could there be a security risk from the implementation, specifically on word-at-a-time comparison? I'd need to look at the kernel's `strncmp` implementation. This is critical. If `strncmp` only reads up to the null byte, the uninitialized part of the stack buffer, will never be read. So, the key takeaway is information disclosure! If an attacker writes a new pattern shorter than `CORENAME_MAX_SIZE` to `pattern` on the stack, that's fine. If there is a read operation, then the uninitialized bytes of the stack will be read out, potentially leaking data. This is a subtle information disclosure vulnerability.
68/3	2026/09/15 13:09	tool	grepper	0m Args: { "Expression": "int strncmp" } Results: { "Output": "arch/arm64/include/asm/string.h=16=extern int strcmp(const char , const char );\n--\narch/arm64/include/asm/string.h-18-#define __HAVE_ARCH_STRNCMP\narch/arm64/include/asm/string.h:19:extern int strncmp(const char , const char , __kernel_size_t);\narch/arm64/include/asm/string.h-20-\n--\narch/powerpc/boot/string.h=10=extern int strcmp(const char s1, const char s2);\narch/powerpc/boot/string.h:11:extern int strncmp(const char s1, const char s2, size_t n);\narch/powerpc/boot/string.h-12-extern size_t strlen(const char s);\n--\narch/powerpc/include/asm/string.h=21=extern int strcmp(const char ,const char );\narch/powerpc/include/asm/string.h:22:extern int strncmp(const char , const char , __kernel_size_t);\narch/powerpc/include/asm/string.h-23-extern char strcat(char , const char );\n--\narch/riscv/include/asm/string.h=27=extern asmlinkage __kernel_size_t strlen(const char );\n--\narch/riscv/include/asm/string.h-29-#define __HAVE_ARCH_STRNCMP\narch/riscv/include/asm/string.h:30:extern asmlinkage int strncmp(const char cs, const char ct, size_t count);\narch/riscv/include/asm/string.h-31-\n--\narch/riscv/lib/strncmp.S-7-\narch/riscv/lib/strncmp.S:8:/ int strncmp(const char cs, const char ct, size_t count) /\narch/riscv/lib/strncmp.S-9-SYM_FUNC_START(strncmp)\n--\narch/s390/boot/string.c-15-\narch/s390/boot/string.c:16:int strncmp(const char cs, const char ct, size_t count)\narch/s390/boot/string.c-17-{\n--\narch/sh/include/asm/string_32.h=30=static inline int strcmp(const char __cs, const char __ct)\n--\narch/sh/include/asm/string_32.h-55-#define __HAVE_ARCH_STRNCMP\narch/sh/include/asm/string_32.h:56:static inline int strncmp(const char __cs, const char __ct, size_t __n)\narch/sh/include/asm/string_32.h-57-{\n--\narch/sparc/include/asm/string.h=42=__kernel_size_t strlen(const char );\n--\narch/sparc/include/asm/string.h-44-#define __HAVE_ARCH_STRNCMP\narch/sparc/include/asm/string.h:45:int strncmp(const char , const char , __kernel_size_t);\narch/sparc/include/asm/string.h-46-\n--\narch/x86/boot/boot.h=303=int strcmp(const char str1, const char str2);\narch/x86/boot/boot.h:304:int strncmp(const char cs, const char ct, size_t count);\narch/x86/boot/boot.h-305-size_t strnlen(const char s, size_t maxlen);\n--\narch/x86/boot/string.c=55=int strcmp(const char str1, const char str2)\n--\narch/x86/boot/string.c-70-\narch/x86/boot/string.c:71:int strncmp(const char cs, const char ct, size_t count)\narch/x86/boot/string.c-72-{\n--\narch/x86/boot/string.h=21=extern int strcmp(const char str1, const char str2);\narch/x86/boot/string.h:22:extern int strncmp(const char cs, const char ct, size_t count);\narch/x86/boot/string.h-23-extern size_t strlen(const char s);\n--\narch/x86/include/asm/string_32.h=19=extern int strcmp(const char cs, const char ct);\n--\narch/x86/include/asm/string_32.h-21-#define __HAVE_ARCH_STRNCMP\narch/x86/include/asm/string_32.h:22:extern int strncmp(const char cs, const char ct, size_t count);\narch/x86/include/asm/string_32.h-23-\n--\narch/x86/lib/string_32.c=93=EXPORT_SYMBOL(strcmp);\n--\narch/x86/lib/string_32.c-96-#ifdef __HAVE_ARCH_STRNCMP\narch/x86/lib/string_32.c:97:int strncmp(const char cs, const char ct, size_t count)\narch/x86/lib/string_32.c-98-{\n--\narch/xtensa/include/asm/string.h=38=static inline int strcmp(const char __cs, const char __ct)\n--\narch/xtensa/include/asm/string.h-59-#define __HAVE_ARCH_STRNCMP\narch/xtensa/include/asm/string.h:60:static inline int strncmp(const char __cs, const char __ct, size_t __n)\narch/xtensa/include/asm/string.h-61-{\n--\ndrivers/firmware/efi/libstub/string.c=73=int strcmp(const char cs, const char ct)\n--\ndrivers/firmware/efi/libstub/string.c-94- /\ndrivers/firmware/efi/libstub/string.c:95:int strncmp(const char cs, const char ct, size_t count)\ndrivers/firmware/efi/libstub/string.c-96-{\n--\ninclude/linux/string.h=158=extern int strcmp(const char ,const char );\n--\ninclude/linux/string.h-160-#ifndef __HAVE_ARCH_STRNCMP\ninclude/linux/string.h:161:extern int strncmp(const char ,const char ,__kernel_size_t);\ninclude/linux/string.h-162-#endif\n--\nlib/string.c=274=EXPORT_SYMBOL(strcmp);\n--\nlib/string.c-283- /\nlib/string.c:284:int strncmp(const char cs, const char ct, size_t count)\nlib/string.c-285-{\n--\ntools/include/nolibc/string.h=273=static __attribute__((unused))\ntools/include/nolibc/string.h:274:int strncmp(const char a, const char b, size_t size)\ntools/include/nolibc/string.h-275-{\n--\ntools/testing/selftests/bpf/progs/strncmp_bench.c=35=SEC(\"tp/syscalls/sys_enter_getpgid\")\ntools/testing/selftests/bpf/progs/strncmp_bench.c:36:int strncmp_no_helper(void ctx)\ntools/testing/selftests/bpf/progs/strncmp_bench.c-37-{\n--\ntools/testing/selftests/bpf/progs/strncmp_bench.c=46=SEC(\"tp/syscalls/sys_enter_getpgid\")\ntools/testing/selftests/bpf/progs/strncmp_bench.c:47:int strncmp_helper(void ctx)\ntools/testing/selftests/bpf/progs/strncmp_bench.c-48-{\n--\ntools/testing/selftests/bpf/progs/strncmp_test.c=32=SEC(\"?tp/syscalls/sys_enter_nanosleep\")\ntools/testing/selftests/bpf/progs/strncmp_test.c:33:int strncmp_bad_not_const_str_size(void ctx)\ntools/testing/selftests/bpf/progs/strncmp_test.c-34-{\n--\ntools/testing/selftests/bpf/progs/strncmp_test.c=40=SEC(\"?tp/syscalls/sys_enter_nanosleep\")\ntools/testing/selftests/bpf/progs/strncmp_test.c:41:int strncmp_bad_writable_target(void ctx)\ntools/testing/selftests/bpf/progs/strncmp_test.c-42-{\n--\ntools/testing/selftests/bpf/progs/strncmp_test.c=48=SEC(\"?tp/syscalls/sys_enter_nanosleep\")\ntools/testing/selftests/bpf/progs/strncmp_test.c:49:int strncmp_bad_not_null_term_target(void *ctx)\ntools/testing/selftests/bpf/progs/strncmp_test.c-50-{\n" }
69/3	2026/09/15 13:09	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 22939 output: 33 thoughts: 18 Thoughts: Here's my take on the thought process, as requested: Diving into `lib/string.c` Alright, time to troubleshoot this. My initial instinct is telling me there's something amiss within the string manipulation code, and that often leads me straight to the heart of the matter. My mental map is guiding me towards `lib/string.c`. I need to inspect the core string handling functions – that's usually where the subtle bugs like this like to hide. And, if my memory serves, line 284 might be a good starting point. It feels like the right area to start investigating for the root cause. Let's see what’s cooking there.
70/3	2026/09/15 13:09	tool	read-file	0m Args: { "File": "lib/string.c", "FirstLine": 280, "LineCount": 20 } Results: { "Contents": " 280:\t * @cs: One string\n 281:\t * @ct: Another string\n 282:\t * @count: The maximum number of bytes to compare\n 283:\t /\n 284:\tint strncmp(const char cs, const char ct, size_t count)\n 285:\t{\n 286:\t\tunsigned char c1, c2;\n 287:\t\n 288:\t\twhile (count) {\n 289:\t\t\tc1 = cs++;\n 290:\t\t\tc2 = *ct++;\n 291:\t\t\tif (c1 != c2)\n 292:\t\t\t\treturn c1 \u003c c2 ? -1 : 1;\n 293:\t\t\tif (!c1)\n 294:\t\t\t\tbreak;\n 295:\t\t\tcount--;\n 296:\t\t}\n 297:\t\treturn 0;\n 298:\t}\n 299:\tEXPORT_SYMBOL(strncmp);\n" }
71/3	2026/09/15 13:09	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 23402 output: 29 thoughts: 251 Thoughts: My Analysis of `core_pattern` and String Handling Okay, so I'm digging into this code and my initial thought is, `strncmp` has this quick exit condition: it bails as soon as it sees a null byte in either string, right? Even if both characters are initially zero, it'll return 0, which is something to keep in mind. And given both `pattern` and `core_pattern` are null-terminated strings, that initial check seems important. Now, my main concern is, is there any possibility that `core_pattern` or `pattern` are read past their null terminators? I need to know this definitively. This is a potential vulnerability, and a big one if it exists. Wait, the function `strscpy(core_pattern, pattern)` is used to copy them around. Okay, `strscpy` reads from `pattern` until it hits a null byte, copies that into `core_pattern`, and null-terminates `core_pattern`. That's the basic function of the copy. But that makes me think about a specific case. What if `core_pattern` was initially longer? Let's say it starts as "core_pattern_long" and we then overwrite it with just "abc". `strscpy` will write 'a', 'b', 'c', '\0' to `core_pattern`. That would mean that the rest of `core_pattern` still holds the old characters, and isn't necessarily null-terminated. The crucial question is, does any other part of the code read past that `\0` in `core_pattern`? Is there some point where an access or comparison, something like `strlen` or another string operation on the `core_pattern`, could read past the intended termination, potentially leading to a buffer overflow or information leak? I'm going to track down every instance of `core_pattern` in `fs/coredump.c` to be certain.
72/3	2026/09/15 13:10	tool	grepper	0m Args: { "Expression": "core_pattern", "PathPrefix": "fs/coredump.c" } Results: { "Output": "fs/coredump.c=87=static unsigned int core_sort_vma;\nfs/coredump.c:88:static char core_pattern[CORENAME_MAX_SIZE] = \"core\";\nfs/coredump.c:89:/* Taken around every copy in and out of core_pattern. /\nfs/coredump.c:90:static DEFINE_SPINLOCK(core_pattern_lock);\nfs/coredump.c-91-static int core_name_size = CORENAME_MAX_SIZE;\n--\nfs/coredump.c=242=static bool coredump_parse(struct core_name cn, struct coredump_params cprm,\n--\nfs/coredump.c-252-\t/ The sysctl handler may be publishing a new pattern. /\nfs/coredump.c:253:\tscoped_guard(spinlock, \u0026core_pattern_lock)\nfs/coredump.c:254:\t\tstrscpy(pattern, core_pattern);\nfs/coredump.c-255-\n--\nfs/coredump.c-273-\tcase COREDUMP_PIPE: {\nfs/coredump.c:274:\t\tint argvs = sizeof(core_pattern) / 2;\nfs/coredump.c-275-\t\t(argv) = kmalloc_objs(*argv, argvs);\n--\nfs/coredump.c-480-\t \nfs/coredump.c:481:\t * If core_pattern does not include a %p (as is the default)\nfs/coredump.c-482-\t * and core_uses_pid is set, then .%pid will be appended to\n--\nfs/coredump.c=1116=static bool coredump_pipe(struct core_name cn, struct coredump_params cprm,\n--\nfs/coredump.c-1129-\t\t * consistent way to catch recursive crashes.\nfs/coredump.c:1130:\t\t * We can still crash if the core_pattern binary sets\nfs/coredump.c-1131-\t\t * RLIM_CORE = !1, but it runs as root, and can do\n--\nfs/coredump.c-1136-\t\t * right pid if a thread in a multi-threaded\nfs/coredump.c:1137:\t\t * core_pattern process dies.\nfs/coredump.c-1138-\t\t /\n--\nfs/coredump.c=1689=void validate_coredump_safety(void)\n--\nfs/coredump.c-1691-\tif (suid_dumpable == TASK_DUMPABLE_ROOT \u0026\u0026\nfs/coredump.c:1692:\t core_pattern[0] != '/' \u0026\u0026 core_pattern[0] != '\|' \u0026\u0026 core_pattern[0] != '@') {\nfs/coredump.c-1693-\nfs/coredump.c:1694:\t\tcoredump_report_failure(\"Unsafe core_pattern used with fs.suid_dumpable=2: \"\nfs/coredump.c-1695-\t\t\t\"pipe handler or fully qualified core dump path required. \"\nfs/coredump.c:1696:\t\t\t\"Set kernel.core_pattern before fs.suid_dumpable.\");\nfs/coredump.c-1697-\t}\n--\nfs/coredump.c=1739=static int proc_dostring_coredump(const struct ctl_table table, int write,\n--\nfs/coredump.c-1751-\t/* Work on a copy, proc_dostring() appends at ppos. /\nfs/coredump.c:1752:\tscoped_guard(spinlock, \u0026core_pattern_lock)\nfs/coredump.c:1753:\t\tstrscpy(pattern, core_pattern);\nfs/coredump.c-1754-\n--\nfs/coredump.c-1762-\t/* Publish the validated pattern whole. */\nfs/coredump.c:1763:\tscoped_guard(spinlock, \u0026core_pattern_lock) {\nfs/coredump.c:1764:\t\tchanged = strncmp(pattern, core_pattern, CORENAME_MAX_SIZE);\nfs/coredump.c:1765:\t\tstrscpy(core_pattern, pattern);\nfs/coredump.c-1766-\t}\n--\nfs/coredump.c=1781=static const struct ctl_table coredump_sysctls[] = {\n--\nfs/coredump.c-1789-\t{\nfs/coredump.c:1790:\t\t.procname\t= \"core_pattern\",\nfs/coredump.c:1791:\t\t.data\t\t= core_pattern,\nfs/coredump.c-1792-\t\t.maxlen\t\t= CORENAME_MAX_SIZE,\n" }
73/3	2026/09/15 13:10	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 25314 output: 35 thoughts: 107 Thoughts: Analyzing Core Dump Configuration Okay, let's dive into this `coredump_sysctls` structure. I'm focusing on the `core_pattern` entry right now. The structure shows the `core_pattern`'s data and maximum length. Now, my mind immediately goes to the handler function. I need to confirm if `proc_dostring_coredump` is indeed being used as the `.proc_handler` for `core_pattern`. It's a key detail for understanding how this system variable is managed. So, time to check `fs/coredump.c`, specifically around lines 1780 to 1800, to be certain. I need to verify that connection.
74/3	2026/09/15 13:11	tool	read-file	0m Args: { "File": "fs/coredump.c", "FirstLine": 1780, "LineCount": 30 } Results: { "Contents": "1780:\t\n1781:\tstatic const struct ctl_table coredump_sysctls[] = {\n1782:\t\t{\n1783:\t\t\t.procname\t= \"core_uses_pid\",\n1784:\t\t\t.data\t\t= \u0026core_uses_pid,\n1785:\t\t\t.maxlen\t\t= sizeof(int),\n1786:\t\t\t.mode\t\t= 0644,\n1787:\t\t\t.proc_handler\t= proc_dointvec,\n1788:\t\t},\n1789:\t\t{\n1790:\t\t\t.procname\t= \"core_pattern\",\n1791:\t\t\t.data\t\t= core_pattern,\n1792:\t\t\t.maxlen\t\t= CORENAME_MAX_SIZE,\n1793:\t\t\t.mode\t\t= 0644,\n1794:\t\t\t.proc_handler\t= proc_dostring_coredump,\n1795:\t\t},\n1796:\t\t{\n1797:\t\t\t.procname\t= \"core_pipe_limit\",\n1798:\t\t\t.data\t\t= \u0026core_pipe_limit,\n1799:\t\t\t.maxlen\t\t= sizeof(unsigned int),\n1800:\t\t\t.mode\t\t= 0644,\n1801:\t\t\t.proc_handler\t= proc_dointvec_minmax,\n1802:\t\t\t.extra1\t\t= SYSCTL_ZERO,\n1803:\t\t\t.extra2\t\t= SYSCTL_INT_MAX,\n1804:\t\t},\n1805:\t\t{\n1806:\t\t\t.procname = \"core_file_note_size_limit\",\n1807:\t\t\t.data = \u0026core_file_note_size_limit,\n1808:\t\t\t.maxlen = sizeof(unsigned int),\n1809:\t\t\t.mode = 0644,\n" }
75/3	2026/09/15 13:11	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 26093 output: 21 thoughts: 759 Thoughts: Analyzing the Core Dump Pattern Change Okay, let's break this down. Before this patch, in `proc_dostring_coredump`, the code worked like this: if it wasn't a write operation (`!write`), it simply called `proc_dostring` directly. If it was a write, it copied the existing core pattern, updated it, checked it, and then validated the safety of the change. This seemed straightforward. Now, things are different. The new version introduces a local buffer `pattern` to work with, using a spinlock to protect the critical section. The core logic now involves creating a temporary control table (`tmp`) that points to this local `pattern`. Crucially, let's focus on the `!write` case: when the operation is a read. The new code still copies the current `core_pattern` into the local `pattern` buffer, even when reading. Then it calls `proc_dostring` on the temporary table using the local buffer. I see the importance now. In this instance `proc_dostring` handles the read. So I'm interested in the `buffer` passed in the `proc_dostring` call. So, when reading from `/proc/sys/kernel/core_pattern`, `write` is 0, so this section gets executed. The `pattern` buffer contains the current `core_pattern` and then the `proc_dostring` function is then called. In `proc_dostring`, the length of the copied `pattern` is determined with `strlen()`, which is copied into the `buffer` with `memcpy()`. But what is `buffer`? It is passed down from the sysctl handler. Is it a kernel buffer, or a user-space buffer? This is the critical question. I need to trace this back. Is it called with `proc_sys_call_handler` or a similar function? I need to check the broader sysctl infrastructure. I need to be sure that the buffer is the one that's expected. I'm going to look there next.
76/3	2026/09/15 13:11	tool	grepper	0m Args: { "Expression": "proc_sys_call_handler" } Results: { "Output": "fs/proc/proc_sysctl.c=515=static struct dentry proc_sys_lookup(struct inode dir, struct dentry dentry,\n--\nfs/proc/proc_sysctl.c-552-\nfs/proc/proc_sysctl.c:553:static ssize_t proc_sys_call_handler(struct kiocb iocb, struct iov_iter iter,\nfs/proc/proc_sysctl.c-554-\t\tint write)\n--\nfs/proc/proc_sysctl.c=619=static ssize_t proc_sys_read(struct kiocb iocb, struct iov_iter iter)\nfs/proc/proc_sysctl.c-620-{\nfs/proc/proc_sysctl.c:621:\treturn proc_sys_call_handler(iocb, iter, 0);\nfs/proc/proc_sysctl.c-622-}\n--\nfs/proc/proc_sysctl.c=624=static ssize_t proc_sys_write(struct kiocb iocb, struct iov_iter iter)\nfs/proc/proc_sysctl.c-625-{\nfs/proc/proc_sysctl.c:626:\treturn proc_sys_call_handler(iocb, iter, 1);\nfs/proc/proc_sysctl.c-627-}\n--\nnet/netfilter/ipvs/ip_vs_ctl.c=2555=static int ipvs_proc_est_cpulist(const struct ctl_table table, int write,\n--\nnet/netfilter/ipvs/ip_vs_ctl.c-2565-\tif (write) {\nnet/netfilter/ipvs/ip_vs_ctl.c:2566:\t\t/* proc_sys_call_handler() appends terminator /\nnet/netfilter/ipvs/ip_vs_ctl.c-2567-\t\tret = ipvs_proc_est_cpumask_set(table, buffer);\n--\nnet/netfilter/ipvs/ip_vs_ctl.c-2570-\t} else {\nnet/netfilter/ipvs/ip_vs_ctl.c:2571:\t\t/ proc_sys_call_handler() allocates 1 byte for terminator /\nnet/netfilter/ipvs/ip_vs_ctl.c-2572-\t\tret = ipvs_proc_est_cpumask_get(table, buffer, lenp + 1);\n" }
77/3	2026/09/15 13:11	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 27952 output: 38 thoughts: 27 Thoughts: Here's my take on the thought process, as requested: Diving into the Kernel's System Call Handling Okay, so I'm digging into how the kernel handles system calls, and I want to see how the `/proc` filesystem plays into this, specifically the system control aspect. My focus is on the `proc_sys_call_handler` function located within `fs/proc/proc_sysctl.c`. I'm going to carefully analyze what this function does, how it's structured, and how it's integrated with the larger system call infrastructure, from the user-level through to the core kernel. I'm hoping to understand how system-level configuration and control is managed via the `/proc` file system, and this looks like a good place to start.
78/3	2026/09/15 13:11	tool	read-file	0m Args: { "File": "fs/proc/proc_sysctl.c", "FirstLine": 550, "LineCount": 70 } Results: { "Contents": " 550:\t\treturn err;\n 551:\t}\n 552:\t\n 553:\tstatic ssize_t proc_sys_call_handler(struct kiocb iocb, struct iov_iter iter,\n 554:\t\t\tint write)\n 555:\t{\n 556:\t\tstruct inode inode = file_inode(iocb-\u003eki_filp);\n 557:\t\tstruct ctl_table_header head = grab_header(inode);\n 558:\t\tconst struct ctl_table table = PROC_I(inode)-\u003esysctl_entry;\n 559:\t\tsize_t count = iov_iter_count(iter);\n 560:\t\tchar kbuf;\n 561:\t\tssize_t error;\n 562:\t\n 563:\t\tif (IS_ERR(head))\n 564:\t\t\treturn PTR_ERR(head);\n 565:\t\n 566:\t\t/\n 567:\t\t At this point we know that the sysctl was not unregistered\n 568:\t\t * and won't be until we finish.\n 569:\t\t /\n 570:\t\terror = -EPERM;\n 571:\t\tif (sysctl_perm(head, table, write ? MAY_WRITE : MAY_READ))\n 572:\t\t\tgoto out;\n 573:\t\n 574:\t\t/ if that can happen at all, it should be -EINVAL, not -EISDIR /\n 575:\t\terror = -EINVAL;\n 576:\t\tif (!table-\u003eproc_handler)\n 577:\t\t\tgoto out;\n 578:\t\n 579:\t\t/ don't even try if the size is too large /\n 580:\t\terror = -ENOMEM;\n 581:\t\tif (count \u003e= KMALLOC_MAX_SIZE)\n 582:\t\t\tgoto out;\n 583:\t\tkbuf = kvzalloc(count + 1, GFP_KERNEL);\n 584:\t\tif (!kbuf)\n 585:\t\t\tgoto out;\n 586:\t\n 587:\t\tif (write) {\n 588:\t\t\terror = -EFAULT;\n 589:\t\t\tif (!copy_from_iter_full(kbuf, count, iter))\n 590:\t\t\t\tgoto out_free_buf;\n 591:\t\t\tkbuf[count] = '\\0';\n 592:\t\t}\n 593:\t\n 594:\t\terror = BPF_CGROUP_RUN_PROG_SYSCTL(head, table, write, \u0026kbuf, \u0026count,\n 595:\t\t\t\t\t\t \u0026iocb-\u003eki_pos);\n 596:\t\tif (error)\n 597:\t\t\tgoto out_free_buf;\n 598:\t\n 599:\t\t/ careful: calling conventions are nasty here /\n 600:\t\terror = table-\u003eproc_handler(table, write, kbuf, \u0026count, \u0026iocb-\u003eki_pos);\n 601:\t\tif (error)\n 602:\t\t\tgoto out_free_buf;\n 603:\t\n 604:\t\tif (!write) {\n 605:\t\t\terror = -EFAULT;\n 606:\t\t\tif (copy_to_iter(kbuf, count, iter) \u003c count)\n 607:\t\t\t\tgoto out_free_buf;\n 608:\t\t}\n 609:\t\n 610:\t\terror = count;\n 611:\tout_free_buf:\n 612:\t\tkvfree(kbuf);\n 613:\tout:\n 614:\t\tsysctl_head_finish(head);\n 615:\t\n 616:\t\treturn error;\n 617:\t}\n 618:\t\n 619:\tstatic ssize_t proc_sys_read(struct kiocb iocb, struct iov_iter *iter)\n" }
79/3	2026/09/15 13:11	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 29203 output: 32 thoughts: 2178 Thoughts: Analyzing the Core Dump Patch: Security Implications Okay, let's break this down systematically. My initial thought was to examine the `proc_sys_call_handler` function and the interaction with the `core_pattern`. I was concerned about potential buffer overflows when copying the `core_pattern` to user space via the `kbuf`. I saw the zero-allocation of `kbuf`, then the `copy_to_iter`, but I was relieved to see the logic in `_proc_do_string` using `strlen` of the data (which is `pattern`), and the check `if (len > lenp) len = lenp;` ensuring we don't copy more than the provided length. Crucially, the use of `strscpy(pattern, core_pattern)` makes sure `pattern` is null-terminated, which stops the `strlen` and `memcpy` from going past the end of the real string. Even the `ppos` offset logic still keeps us within the bounds of the null-terminated `pattern`. I then checked that `strncmp` never reads past the null terminator, either! I then worried that `pattern` could somehow* not be null-terminated, but I've confirmed that the code _always_ null-terminates the `pattern` variable after it's been copied from `core_pattern`, and that any other possible string access to pattern also operates strictly within null-terminated bounds. Even when checking the socket file with the `check_coredump_socket`, it checks the `\0` character. Now, let's step back and look at the bigger picture. I need to review all the code changes to see if there are other areas of concern. In `coredump_parse`, I see the introduction of a local `pattern` buffer on the stack, and a spinlock guarding access to `core_pattern`, so I know that access to `core_pattern` is being synchronized, now, and a local copy is made. The code then uses this local `pattern`, and it’s being passed around through `pat_ptr`. I meticulously checked every instance where `pat_ptr` is dereferenced in `coredump_parse`. The code safely stops at null terminators. There are checks against null characters everywhere! This is good. Finally, in the second part of the patch, the `coredump_close_files` function seems to have been modified. I need to make sure this code is safe. Specifically, I see `switch_files_struct` and `put_files_struct` and I need to make sure the change is correct. It seems the code is correctly checking the `current->files` pointer, so it's probably safe. So, in conclusion, after a rigorous review, I'm confident that these changes don't introduce any new vulnerabilities related to buffer overflows or arbitrary code execution from the core pattern!
80/3	2026/09/15 13:11	tool	grepper	0m Args: { "Expression": "coredump_close_files", "PathPrefix": "fs/coredump.c" } Results: { "Output": "fs/coredump.c=546=static int coredump_wait(int exit_code, struct core_state core_state)\n--\nfs/coredump.c-564- /\nfs/coredump.c:565:static bool coredump_close_files(struct core_state core_state)\nfs/coredump.c-566-{\n--\nfs/coredump.c=1247=static void do_coredump(struct core_name cn, struct coredump_params *cprm,\n--\nfs/coredump.c-1281-\tif ((cprm-\u003emask \u0026 COREDUMP_CLOSE_FILES) \u0026\u0026\nfs/coredump.c:1282:\t !coredump_close_files(current-\u003esignal-\u003ecore_state))\nfs/coredump.c-1283-\t\treturn;\n" }
81/3	2026/09/15 13:11	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 32256 output: 34 thoughts: 22 Thoughts: Here's my summary, as though I'm reading and processing the `fs/coredump.c` code: Diving into `fs/coredump.c` - Line 565-600 Okay, let's zero in on lines 565 through 600 in `fs/coredump.c`. Right, I'm expecting this to deal with the core dump process itself, probably at the point where we're handling the file writing. Let's see... Ah, it's inside `__coredump_file_write()`. Okay, makes sense. This function must handle the actual writing of the core dump data to the core file. So, here we are; it looks like this section is about managing potential write errors during the process. We start with the amount to be written `bytes_to_write`. We check this against the remaining space, and adjust the write parameters as needed, if the requested amount exceeds the buffer size. It's handling scenarios where the write might be partial and then looping back to retry writing the remaining data. Looks like it is using `vfs_write()` to write the buffer. The loop condition appears to be checking for write errors and retrying. I'm noting the use of `p->offset` and `count`, indicating we're dealing with a specific offset within the core file and a write count. I see a check for `err < 0`, indicating a write error. If we encounter an error, it looks like it's attempting to handle it gracefully, probably returning an error code. I'm focusing on the error handling; this is a critical part. We don't want a partially written core dump. We need to catch these issues. It seems it is logging the error and adjusting the `bytes_to_write`. The retry logic here is key; if the write fails, we try again with what's left. The logic seems robust; it's considering various error conditions, and the repeated writes, together with error checking and `vfs_write()` calls, are critical for a proper core dump file. Looks solid so far. I'm going to scan the surrounding code for how these errors are handled up the call stack, but on first read, this section looks good.
82/3	2026/09/15 13:12	tool	read-file	0m Args: { "File": "fs/coredump.c", "FirstLine": 565, "LineCount": 40 } Results: { "Contents": " 565:\tstatic bool coredump_close_files(struct core_state core_state)\n 566:\t{\n 567:\t\tstruct files_struct files;\n 568:\t\tstruct core_thread ct;\n 569:\t\n 570:\t\tfiles = alloc_files_struct();\n 571:\t\tif (!files)\n 572:\t\t\treturn false;\n 573:\t\n 574:\t\tfor (ct = core_state-\u003etasks; ct; ct = ct-\u003enext) {\n 575:\t\t\t/ Tasks without a table such as vhost workers can be skipped. /\n 576:\t\t\tif (!ct-\u003etask-\u003efiles)\n 577:\t\t\t\tcontinue;\n 578:\t\t\tatomic_inc(\u0026core_state-\u003ethreads_remaining);\n 579:\t\t\t/ ct-\u003efiles holds a reference until the thread switches to it. /\n 580:\t\t\tatomic_inc(\u0026files-\u003ecount);\n 581:\t\t\t/ Pairs with the acquire in coredump_task_exit(). /\n 582:\t\t\tsmp_store_release(\u0026ct-\u003efiles, files);\n 583:\t\t\twake_up_process(ct-\u003etask);\n 584:\t\t}\n 585:\t\n 586:\t\t/ Use the dumper's real creds not the overridden ones. /\n 587:\t\tscoped_with_creds(current_real_cred()) {\n 588:\t\t\tio_uring_task_cancel();\n 589:\t\t\t/ The dumper itself may be a vhost worker without a table. /\n 590:\t\t\tif (current-\u003efiles)\n 591:\t\t\t\tswitch_files_struct(current, files);\n 592:\t\t\telse\n 593:\t\t\t\tput_files_struct(files);\n 594:\t\t}\n 595:\t\n 596:\t\tcoredump_wait_inactive(core_state);\n 597:\t\treturn true;\n 598:\t}\n 599:\t\n 600:\tstatic void coredump_finish(enum coredump_state state)\n 601:\t{\n 602:\t\tstruct core_thread curr, next;\n 603:\t\tstruct task_struct task;\n 604:\t\n" }
83/3	2026/09/15 13:12	llm	kmsan-evaluator	0m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 33387 output: 34 thoughts: 236 Thoughts: My Analysis of `coredump_close_files` and `coredump_finish` for Core Dumps Okay, so I'm looking at this core dump code, specifically the `coredump_close_files` function. I see that it's checking `current->files`. Now, that's crucial because if `current->files` is NULL, which could happen, for instance, with a vhost worker, then we need to call `put_files_struct(files)` instead of `switch_files_struct(current, files)`. Right, that makes perfect sense. Avoiding that `switch_files_struct` in that NULL case will prevent a nasty NULL pointer dereference. Got it. Avoiding that subtle crash is a good catch. Now, moving on to the `coredump_finish` function. Specifically, let's focus on the area around lines 600-630. I see they've added a `guard(rcu)()` call, likely to handle a released thread that might exit and get freed before it's woken. Interesting. I'll need to dig into how `task` is used within that `while` loop to understand the implications of this RCU protection. Let me scan up and down to see how `task` is used in that context...
84/3	2026/09/15 13:12	tool	read-file	0m Args: { "File": "fs/coredump.c", "FirstLine": 600, "LineCount": 35 } Results: { "Contents": " 600:\tstatic void coredump_finish(enum coredump_state state)\n 601:\t{\n 602:\t\tstruct core_thread curr, next;\n 603:\t\tstruct task_struct task;\n 604:\t\n 605:\t\tspin_lock_irq(\u0026current-\u003esighand-\u003esiglock);\n 606:\t\tif ((state \u0026 COREDUMP_STATE_STARTED) \u0026\u0026 !__fatal_signal_pending(current))\n 607:\t\t\tcurrent-\u003esignal-\u003egroup_exit_code \|= 0x80;\n 608:\t\tnext = current-\u003esignal-\u003ecore_state-\u003etasks;\n 609:\t\tcurrent-\u003esignal-\u003ecore_state = NULL;\n 610:\t\tspin_unlock_irq(\u0026current-\u003esighand-\u003esiglock);\n 611:\t\n 612:\t\t/ A released thread may exit and be freed before it is woken. /\n 613:\t\tguard(rcu)();\n 614:\t\twhile ((curr = next) != NULL) {\n 615:\t\t\tnext = curr-\u003enext;\n 616:\t\t\ttask = curr-\u003etask;\n 617:\t\t\t/\n 618:\t\t\t * see coredump_task_exit(), curr-\u003etask must not see\n 619:\t\t\t * -\u003etask == NULL before we read -\u003enext.\n 620:\t\t\t /\n 621:\t\t\tsmp_mb();\n 622:\t\t\tcurr-\u003etask = NULL;\n 623:\t\t\twake_up_process(task);\n 624:\t\t}\n 625:\t}\n 626:\t\n 627:\tstatic bool dump_interrupted(void)\n 628:\t{\n 629:\t\t/\n 630:\t\t * SIGKILL or freezing() interrupt the coredumping. Perhaps we\n 631:\t\t * can do try_to_freeze() and check __fatal_signal_pending(),\n 632:\t\t * but then we need to teach dump_write() to restart and clear\n 633:\t\t * TIF_SIGPENDING.\n 634:\t\t */\n" }
85/3	2026/09/15 13:12	llm	kmsan-evaluator	3m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 34481 output: 27 thoughts: 2423 Thoughts: Analyzing Recent Kernel Changes for Potential Issues Okay, let's break down these kernel diffs. The first one involving `guard(rcu)()` and `wake_up_process(task)` is a straightforward use-after-free fix. The RCU read-side critical section protects `task` from being freed before it's woken up, addressing a concurrency issue. Next, I'm looking at the changes to `include/linux/sched/signal.h`. The core of this is the modification to `signal_pending()`. It seems that the logic has been updated so that when a task is coredumping (`PF_DUMPCORE` flag is set), the check for pending signals is now stricter, only considering SIGKILL as a fatal signal. Initially, I thought this might introduce a potential uninitialized memory access, but it's just a check for pending signals; it's safe. Moving on to `io_uring/io-wq.c`, the introduction of `smp_mb__after_atomic()` within `io_wq_exit_start()` is a memory barrier. This is a crucial concurrency fix, ensuring that the `IO_WQ_BIT_EXIT` bit is set after the `task_work_add()` call in the worker thread is completed. It looks like it is to protect against a race condition. Now, let's delve into `kernel/fork.c`. The changes there make the `copy_process()` function abort fork/clone operations if a coredump is in progress. The addition of `current->signal->core_state` to the `fatal_signal_pending()` condition in `copy_process()` means the fork will fail if a coredump is already running or a kill signal is pending, with a clean exit using `goto bad_fork_core_free;`. This seems safe, ensuring that a coredump doesn't interfere with process creation. Now, I'm revisiting the `proc_dostring_coredump` code, which handles the `/proc/sys/kernel/core_pattern` file. I need to be absolutely sure there isn't some subtle vulnerability here, specifically regarding uninitialized memory reads. After reviewing the code, it seems safe because the `pattern` variable is properly null-terminated within its scope. When writing to the `core_pattern` it either overwrites the entire contents or appends in a safe way and is null-terminated. When reading the value, only the initialized parts are copied to the user space buffer. Specifically, the use of `ppos` in `proc_dostring` during a write operation is safe because if `ppos > strlen(pattern)`, the write returns 0, and if `*ppos <= strlen(pattern)`, it overwrites/appends. The `pattern` is always null-terminated after the operations. Then the read from `core_pattern` to user space is safe as `strlen(pattern)` is used to copy the initialized bytes into the user space buffer. The rest of the functions `check_coredump_socket`, `strncmp`, `strscpy`, `validate_coredump_safety` ensure no uninitialized memory. Finally, examining the use of `core_pattern` in `fs/coredump.c` doesn't reveal any vulnerabilities.
86/3	2026/09/15 13:15	tool	grepper	0m Args: { "Expression": "argv", "PathPrefix": "fs/coredump.c" } Results: { "Output": "fs/coredump.c=242=static bool coredump_parse(struct core_name cn, struct coredump_params cprm,\nfs/coredump.c:243:\t\t\t size_t *argv, int argc)\nfs/coredump.c-244-{\n--\nfs/coredump.c-273-\tcase COREDUMP_PIPE: {\nfs/coredump.c:274:\t\tint argvs = sizeof(core_pattern) / 2;\nfs/coredump.c:275:\t\t(argv) = kmalloc_objs(argv, argvs);\nfs/coredump.c:276:\t\tif (!(argv))\nfs/coredump.c-277-\t\t\treturn false;\nfs/coredump.c:278:\t\t(argv)[(argc)++] = 0;\nfs/coredump.c-279-\t\t++pat_ptr;\n--\nfs/coredump.c-358-\t\t\t\t\treturn false;\nfs/coredump.c:359:\t\t\t\t(argv)[(argc)++] = cn-\u003eused;\nfs/coredump.c-360-\t\t\t}\n--\nfs/coredump.c=1116=static bool coredump_pipe(struct core_name cn, struct coredump_params cprm,\nfs/coredump.c:1117:\t\t\t size_t argv, int argc)\nfs/coredump.c-1118-{\nfs/coredump.c-1119-\tint argi;\nfs/coredump.c:1120:\tchar helper_argv __free(kfree) = NULL;\nfs/coredump.c-1121-\tstruct subprocess_info sub_info;\n--\nfs/coredump.c-1149-\nfs/coredump.c:1150:\thelper_argv = kmalloc_objs(helper_argv, argc + 1);\nfs/coredump.c:1151:\tif (!helper_argv) {\nfs/coredump.c-1152-\t\tcoredump_report_failure(\"%s failed to allocate memory\", __func__);\n--\nfs/coredump.c-1155-\tfor (argi = 0; argi \u003c argc; argi++)\nfs/coredump.c:1156:\t\thelper_argv[argi] = cn-\u003ecorename + argv[argi];\nfs/coredump.c:1157:\thelper_argv[argi] = NULL;\nfs/coredump.c-1158-\nfs/coredump.c:1159:\tsub_info = call_usermodehelper_setup(helper_argv[0], helper_argv, NULL,\nfs/coredump.c-1160-\t\t\t\t\t GFP_KERNEL, umh_coredump_setup,\n--\nfs/coredump.c=1247=static void do_coredump(struct core_name cn, struct coredump_params cprm,\nfs/coredump.c:1248:\t\t\tsize_t argv, int argc, const struct linux_binfmt binfmt)\nfs/coredump.c-1249-{\n--\nfs/coredump.c-1251-\nfs/coredump.c:1252:\tif (!coredump_parse(cn, cprm, argv, argc)) {\nfs/coredump.c-1253-\t\tcoredump_report_failure(\"format_corename failed, aborting core\");\n--\nfs/coredump.c-1262-\tcase COREDUMP_PIPE:\nfs/coredump.c:1263:\t\tif (!coredump_pipe(cn, cprm, argv, argc))\nfs/coredump.c-1264-\t\t\treturn;\n--\nfs/coredump.c=1319=void vfs_coredump(const kernel_siginfo_t siginfo)\nfs/coredump.c-1320-{\nfs/coredump.c:1321:\tsize_t *argv __free(kfree) = NULL;\nfs/coredump.c-1322-\tstruct core_state core_state;\n--\nfs/coredump.c-1357-\tscoped_with_creds(cred)\nfs/coredump.c:1358:\t\tdo_coredump(\u0026cn, \u0026cprm, \u0026argv, \u0026argc, binfmt);\nfs/coredump.c-1359-\tcoredump_cleanup(\u0026cn, \u0026cprm);\n" }
87/3	2026/09/15 13:15	llm	kmsan-evaluator	1m Model: gemini-3.8-flash Args: null Results: null Tokens: input: 38763 output: 369 thoughts: 1257 Thoughts: KMSAN Evaluation: Patch Review Okay, let's break this down. First, I've got to assess whether this patch requires a KMSAN run, and based on the guidelines, that means looking for uninitialized memory risks. Let me run through each of the code changes methodically. In `fs/coredump.c`, I see a new spinlock, `core_pattern_lock`, and changes to how `core_pattern` is read and used within the coredump process. The `proc_dostring_coredump()` function now uses a local buffer under the lock, and there's a check for `current->files`. The thread iteration in `coredump_finish()` is now protected with `guard(rcu)()`. All of this looks like it’s dealing with concurrency and potential race conditions when writing to/reading from the core pattern sysctl. The files struct changes seem to address a potential NULL pointer dereference. The changes in `include/linux/sched/signal.h` look like an optimization to ensure fatal signals get handled, and `signal_pending` will check `PF_DUMPCORE` . I'm not seeing any new data structures or memory copy here. In `io_uring/io-wq.c`, the `smp_mb__after_atomic()` is added which seems like a fix for a memory ordering race. In `kernel/fork.c`, there's a check `current->signal->core_state` to prevent fork/clone during a coredump. Now, considering the KMSAN guidelines, the key question is, are we introducing or modifying kernel structures sent to userspace with uninitialized padding? Let's see: * The main interaction with userspace is via `proc_dostring`, but it involves copying strings into a `kzalloc`-ed buffer `kbuf`. This is not only initialized but uses `strscpy`, so there are no uninitialized memory leaks. * Are there any conditional branches based on uninitialized variables? I don’t think so. It seems like the critical variables (`pattern`, `core_state`, `signal`, etc.) are all initialized. * Are we introducing the allocation of complex data structures where uninitialized fields could be read later? Again, no. * Are the bounds checks/lengths modified in a way that allows access to uninitialized bytes? The `pattern` is string-copied with `strscpy`, null-terminated, and all string ops respect the null terminator. Looking at the bugs addressed by this patch - concurrency on `core_pattern` (race conditions on sysctl reads/writes), potential NULL pointer dereference, UAF, a memory ordering race, and process fork/signal interaction - all of these are bugs that are normally handled by KASAN, LOCKDEP, and standard kernel debugging tools, NOT KMSAN. Therefore, given the nature of the fixes and the types of bugs that are being addressed, I'm confident that we are not addressing the kind of issues that are caught by KMSAN. There is no risk of uninitialized memory usage or information leaks. Therefore, I'm going to set `NeedsKMSAN` to `false`. Time to call `set-results`.
88/3	2026/09/15 13:16	tool	set-results	0m Args: { "KMSANReasoning": "The patch series addresses concurrency, race conditions, NULL pointer dereferences, and use-after-free issues in the coredump subsystem, io_uring worker exit, and process cloning:\n1. fs/coredump.c: Introduces `core_pattern_lock` spinlock and local stack buffers (`pattern[CORENAME_MAX_SIZE]`) to safely copy and validate `core_pattern` during sysctl read/write and coredump parsing. Strings are copied and null-terminated via `strscpy()`, and all string functions (`strlen`, `strncmp`, `name_contains_dotdot`) operate strictly within null-terminated bounds. No uninitialized bytes are read, branched upon, or leaked to userspace.\n2. fs/coredump.c: Handles tasks without file tables (e.g. vhost workers) to prevent NULL pointer dereferences, and wraps thread wakeups in `coredump_finish()` with `guard(rcu)()` to prevent use-after-free bugs.\n3. include/linux/sched/signal.h \u0026 kernel/fork.c: Adjusts signal pending checks during core dumps and aborts fork/clone if core dumping is in progress.\n4. io_uring/io-wq.c: Adds a memory barrier (`smp_mb__after_atomic()`) to fix a concurrency race.\n\nThese changes deal with locking, concurrency, UAF, and NULL pointer dereferences, all of which are covered by KASAN and LOCKDEP. No uninitialized memory accesses or info-leaks are introduced or exposed, so a dedicated KMSAN session is not warranted.", "NeedsKMSAN": false } Results: { "KMSANReasoning": "The patch series addresses concurrency, race conditions, NULL pointer dereferences, and use-after-free issues in the coredump subsystem, io_uring worker exit, and process cloning:\n1. fs/coredump.c: Introduces `core_pattern_lock` spinlock and local stack buffers (`pattern[CORENAME_MAX_SIZE]`) to safely copy and validate `core_pattern` during sysctl read/write and coredump parsing. Strings are copied and null-terminated via `strscpy()`, and all string functions (`strlen`, `strncmp`, `name_contains_dotdot`) operate strictly within null-terminated bounds. No uninitialized bytes are read, branched upon, or leaked to userspace.\n2. fs/coredump.c: Handles tasks without file tables (e.g. vhost workers) to prevent NULL pointer dereferences, and wraps thread wakeups in `coredump_finish()` with `guard(rcu)()` to prevent use-after-free bugs.\n3. include/linux/sched/signal.h \u0026 kernel/fork.c: Adjusts signal pending checks during core dumps and aborts fork/clone if core dumping is in progress.\n4. io_uring/io-wq.c: Adds a memory barrier (`smp_mb__after_atomic()`) to fix a concurrency race.\n\nThese changes deal with locking, concurrency, UAF, and NULL pointer dereferences, all of which are covered by KASAN and LOCKDEP. No uninitialized memory accesses or info-leaks are introduced or exposed, so a dedicated KMSAN session is not warranted.", "NeedsKMSAN": false }

LLM Calls Summary:
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Tool Calls Summary:
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