==================================================================
BUG: KCSAN: data-race in __bpf_get_stackid / bcmp

write to 0xffff888141ffa190 of 96 bytes by task 3483 on cpu 0:
 __bpf_get_stackid+0x737/0x7d0 kernel/bpf/stackmap.c:311
 ____bpf_get_stackid kernel/bpf/stackmap.c:344 [inline]
 bpf_get_stackid+0xf3/0x130 kernel/bpf/stackmap.c:323
 ____bpf_get_stackid_raw_tp kernel/trace/bpf_trace.c:1628 [inline]
 bpf_get_stackid_raw_tp+0xf6/0x120 kernel/trace/bpf_trace.c:1617
 bpf_prog_53f0063d4d7f65ce+0x2a/0x32
 bpf_dispatcher_nop_func include/linux/bpf.h:1378 [inline]
 __bpf_prog_run include/linux/filter.h:723 [inline]
 bpf_prog_run include/linux/filter.h:730 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2075 [inline]
 bpf_trace_run2+0x107/0x1d0 kernel/trace/bpf_trace.c:2116
 __traceiter_kfree+0x2e/0x50 include/trace/events/kmem.h:97
 __do_trace_kfree include/trace/events/kmem.h:97 [inline]
 trace_kfree include/trace/events/kmem.h:97 [inline]
 kfree+0x353/0x3c0 mm/slub.c:6865
 vfree+0x28d/0x3a0 mm/vmalloc.c:3471
 pcpu_mem_free mm/percpu.c:523 [inline]
 pcpu_free_chunk mm/percpu.c:1493 [inline]
 pcpu_destroy_chunk mm/percpu-vm.c:368 [inline]
 pcpu_balance_free+0x45c/0x580 mm/percpu.c:1981
 pcpu_balance_workfn+0xba8/0xc00 mm/percpu.c:2210
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3340
 worker_thread+0x582/0x770 kernel/workqueue.c:3421
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x149/0x290 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

read to 0xffff888141ffa1c0 of 8 bytes by task 9365 on cpu 1:
 memcmp lib/string.c:683 [inline]
 bcmp+0x23/0x90 lib/string.c:715
 memcmp include/linux/fortify-string.h:727 [inline]
 __bpf_get_stackid+0x382/0x7d0 kernel/bpf/stackmap.c:302
 ____bpf_get_stackid kernel/bpf/stackmap.c:344 [inline]
 bpf_get_stackid+0xf3/0x130 kernel/bpf/stackmap.c:323
 ____bpf_get_stackid_raw_tp kernel/trace/bpf_trace.c:1628 [inline]
 bpf_get_stackid_raw_tp+0xf6/0x120 kernel/trace/bpf_trace.c:1617
 bpf_prog_53f0063d4d7f65ce+0x2a/0x32
 bpf_dispatcher_nop_func include/linux/bpf.h:1378 [inline]
 __bpf_prog_run include/linux/filter.h:723 [inline]
 bpf_prog_run include/linux/filter.h:730 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2075 [inline]
 bpf_trace_run2+0x107/0x1d0 kernel/trace/bpf_trace.c:2116
 __traceiter_kfree+0x2e/0x50 include/trace/events/kmem.h:97
 __do_trace_kfree include/trace/events/kmem.h:97 [inline]
 trace_kfree include/trace/events/kmem.h:97 [inline]
 kfree+0x353/0x3c0 mm/slub.c:6865
 audit_log_d_path+0xf4/0x150 kernel/audit.c:2204
 audit_log_d_path_exe+0x42/0x70 kernel/audit.c:2409
 audit_log_task+0x1e9/0x250 kernel/auditsc.c:2927
 audit_seccomp+0x61/0x100 kernel/auditsc.c:2974
 seccomp_log kernel/seccomp.c:1048 [inline]
 __seccomp_filter+0x843/0x1260 kernel/seccomp.c:1344
 __secure_computing+0x82/0x150 kernel/seccomp.c:1404
 syscall_trace_enter+0xcf/0x1e0 kernel/entry/syscall-common.c:44
 syscall_enter_from_user_mode_work include/linux/entry-common.h:78 [inline]
 syscall_enter_from_user_mode include/linux/entry-common.h:109 [inline]
 do_syscall_64+0xa4/0x2b0 arch/x86/entry/syscall_64.c:90
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffffffff81575a49 -> 0xffffffff818083e8

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 9365 Comm: syz.1.2134 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================