KCSAN: data-race in __set_task_comm / strlen (2)

Status: moderation: reported on 2026/08/04 08:46
Subsystems: fs
Labels: race:benign prio:low
[Documentation on labels]
Reported-by: syzbot+98baf51f5cc36dcbe2f7@syzkaller.appspotmail.com
First crash: 8d16h, last: 3h14m
✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
736576bd assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ KCSAN: data-race in __set_task_comm / strlen (2) 2026/08/09 11:33 2026/08/09 11:33 2026/08/09 12:12 5d63f80b
9011fcab assessment-kcsan Benign: ✅ KCSAN: data-race in __set_task_comm / strlen (2) 2026/08/04 08:45 2026/08/04 08:45 2026/08/04 09:18 9451e17e
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in __set_task_comm / strlen fs mm 6 9 167d 337d 0/29 auto-obsoleted due to no activity on 2026/04/23 17:03

Sample crash report:
==================================================================
BUG: KCSAN: data-race in __set_task_comm / strlen

write to 0xffff888103e44cd8 of 3 bytes by task 19632 on cpu 1:
 __set_task_comm+0x78/0x180 fs/exec.c:1099
 begin_new_exec+0xeb4/0x1210 fs/exec.c:1257
 load_elf_binary+0x64a/0x1a30 fs/binfmt_elf.c:1010
 search_binary_handler fs/exec.c:1694 [inline]
 exec_binprm fs/exec.c:1726 [inline]
 bprm_execve+0x45c/0x9b0 fs/exec.c:1778
 do_execveat_common+0x7a4/0x8a0 fs/exec.c:1876
 __do_sys_execve fs/exec.c:1949 [inline]
 __se_sys_execve fs/exec.c:1943 [inline]
 __x64_sys_execve+0x5f/0x80 fs/exec.c:1943
 x64_sys_call+0x2752/0x3020 arch/x86/include/generated/asm/syscalls_64.h:60
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888103e44cd8 of 1 bytes by task 19627 on cpu 0:
 strlen+0x19/0x40 lib/string.c:402
 __fortify_strlen include/linux/fortify-string.h:218 [inline]
 trace_event_get_offsets_sched_stat_runtime include/trace/events/sched.h:560 [inline]
 do_trace_event_raw_event_sched_stat_runtime include/trace/events/sched.h:553 [inline]
 trace_event_raw_event_sched_stat_runtime+0x59/0x140 include/trace/events/sched.h:553
 __do_trace_sched_stat_runtime include/trace/events/sched.h:576 [inline]
 trace_sched_stat_runtime include/trace/events/sched.h:576 [inline]
 update_se+0x153/0x460 kernel/sched/fair.c:1375
 update_curr+0x29/0x210 kernel/sched/fair.c:2001
 enqueue_entity kernel/sched/fair.c:6121 [inline]
 enqueue_task_fair+0x144/0xab0 kernel/sched/fair.c:7857
 enqueue_task kernel/sched/core.c:2184 [inline]
 activate_task kernel/sched/core.c:2224 [inline]
 ttwu_do_activate+0xa7/0x230 kernel/sched/core.c:3824
 ttwu_queue kernel/sched/core.c:4077 [inline]
 try_to_wake_up+0x44a/0x6c0 kernel/sched/core.c:4415
 wake_up_process kernel/sched/core.c:4547 [inline]
 wake_up_q+0x48/0x80 kernel/sched/core.c:1173
 futex_wake+0x376/0x400 kernel/futex/waitwake.c:225
 do_futex+0x3f8/0x460 kernel/futex/syscalls.c:138
 __do_sys_futex kernel/futex/syscalls.c:210 [inline]
 __se_sys_futex+0x2f6/0x370 kernel/futex/syscalls.c:191
 __x64_sys_futex+0x78/0x90 kernel/futex/syscalls.c:191
 x64_sys_call+0x24ab/0x3020 arch/x86/include/generated/asm/syscalls_64.h:203
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x64 -> 0x73

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 19627 Comm: syz.0.4448 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
==================================================================

Crashes (11):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/12 21:46 upstream 3d6d817622b0 359b2492 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __set_task_comm / strlen
2026/08/11 12:13 upstream d58772d8520c 508909ea .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __set_task_comm / strlen
2026/08/09 08:58 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __set_task_comm / strlen
2026/08/08 20:32 upstream a7c7074b58d2 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __set_task_comm / strlen
2026/08/08 10:15 upstream bcc44b6785f2 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __set_task_comm / strlen
2026/08/08 03:09 upstream bcc44b6785f2 e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __set_task_comm / strlen
2026/08/08 03:06 upstream bcc44b6785f2 e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __set_task_comm / strlen
2026/08/06 23:46 upstream fcaeecb8b0cd c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __set_task_comm / strlen
2026/08/06 06:17 upstream 0d8395707651 cd5b1963 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __set_task_comm / strlen
2026/08/05 10:07 upstream c21bb4193868 52aa2820 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __set_task_comm / strlen
2026/08/04 08:45 upstream 848acc8ffe1b 9451e17e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __set_task_comm / strlen
* Struck through repros no longer work on HEAD.