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BUG: KCSAN: data-race in __bpf_get_stackid / bcmp

write to 0xffff888109933ee0 of 144 bytes by task 3308 on cpu 0:
 __bpf_get_stackid+0x761/0x800 kernel/bpf/stackmap.c:288
 ____bpf_get_stackid kernel/bpf/stackmap.c:324 [inline]
 bpf_get_stackid+0xee/0x120 kernel/bpf/stackmap.c:300
 ____bpf_get_stackid_raw_tp kernel/trace/bpf_trace.c:1810 [inline]
 bpf_get_stackid_raw_tp+0xf6/0x120 kernel/trace/bpf_trace.c:1799
 bpf_prog_e6fc920cfeff8120+0x2a/0x32
 bpf_dispatcher_nop_func include/linux/bpf.h:1332 [inline]
 __bpf_prog_run include/linux/filter.h:718 [inline]
 bpf_prog_run include/linux/filter.h:725 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2257 [inline]
 bpf_trace_run2+0x107/0x1c0 kernel/trace/bpf_trace.c:2298
 __traceiter_kfree+0x2b/0x50 include/trace/events/kmem.h:94
 __do_trace_kfree include/trace/events/kmem.h:94 [inline]
 trace_kfree include/trace/events/kmem.h:94 [inline]
 kfree+0x27b/0x320 mm/slub.c:4881
 security_sk_free+0x38/0x80 security/security.c:4904
 sk_prot_free net/core/sock.c:2271 [inline]
 __sk_destruct+0x392/0x4c0 net/core/sock.c:2373
 sk_destruct net/core/sock.c:2401 [inline]
 __sk_free+0x227/0x270 net/core/sock.c:2412
 sk_free+0x39/0x80 net/core/sock.c:2423
 sock_put include/net/sock.h:1962 [inline]
 tcp_close+0x8d/0xd0 net/ipv4/tcp.c:3278
 inet_release+0xce/0xf0 net/ipv4/af_inet.c:435
 __sock_release net/socket.c:649 [inline]
 sock_close+0x68/0x150 net/socket.c:1439
 __fput+0x298/0x650 fs/file_table.c:468
 fput_close_sync+0x6e/0x120 fs/file_table.c:573
 __do_sys_close fs/open.c:1587 [inline]
 __se_sys_close fs/open.c:1572 [inline]
 __x64_sys_close+0x56/0xf0 fs/open.c:1572
 x64_sys_call+0x2738/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:4
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888109933f40 of 8 bytes by task 3381 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+0x371/0x800 kernel/bpf/stackmap.c:279
 ____bpf_get_stackid kernel/bpf/stackmap.c:324 [inline]
 bpf_get_stackid+0xee/0x120 kernel/bpf/stackmap.c:300
 ____bpf_get_stackid_raw_tp kernel/trace/bpf_trace.c:1810 [inline]
 bpf_get_stackid_raw_tp+0xf6/0x120 kernel/trace/bpf_trace.c:1799
 bpf_prog_e6fc920cfeff8120+0x2a/0x32
 bpf_dispatcher_nop_func include/linux/bpf.h:1332 [inline]
 __bpf_prog_run include/linux/filter.h:718 [inline]
 bpf_prog_run include/linux/filter.h:725 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2257 [inline]
 bpf_trace_run2+0x107/0x1c0 kernel/trace/bpf_trace.c:2298
 __traceiter_kfree+0x2b/0x50 include/trace/events/kmem.h:94
 __do_trace_kfree include/trace/events/kmem.h:94 [inline]
 trace_kfree include/trace/events/kmem.h:94 [inline]
 kfree+0x27b/0x320 mm/slub.c:4881
 ref_tracker_free+0x28d/0x3e0 lib/ref_tracker.c:340
 netdev_tracker_free include/linux/netdevice.h:4369 [inline]
 netdev_put include/linux/netdevice.h:4386 [inline]
 switchdev_deferred_process+0x147/0x240 net/switchdev/switchdev.c:96
 switchdev_deferred_process_work+0x13/0x20 net/switchdev/switchdev.c:105
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0x4cb/0x9d0 kernel/workqueue.c:3319
 worker_thread+0x582/0x770 kernel/workqueue.c:3400
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x11f/0x1b0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0xffffffff812742ba -> 0xffffffff81933b68

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3381 Comm: kworker/1:3 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: events switchdev_deferred_process_work
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