syzbot

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BUG: KCSAN: data-race in __bpf_get_stackid / bcmp

write to 0xffff88811afa3250 of 152 bytes by interrupt 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:1322 [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+0x104/0x1c0 kernel/trace/bpf_trace.c:2298
 __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:4866
 netlbl_secattr_destroy include/net/netlabel.h:367 [inline]
 netlbl_secattr_free include/net/netlabel.h:399 [inline]
 selinux_netlbl_sk_security_free+0x76/0x1d0 security/selinux/netlabel.c:162
 selinux_sk_free_security+0x3b/0x50 security/selinux/hooks.c:5415
 security_sk_free+0x65/0x80 security/security.c:4903
 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:1960 [inline]
 sctp_endpoint_destroy_rcu+0x66/0xb0 net/sctp/endpointola.c:193
 rcu_do_batch kernel/rcu/tree.c:2605 [inline]
 rcu_core+0x5aa/0xc30 kernel/rcu/tree.c:2861
 rcu_core_si+0xd/0x20 kernel/rcu/tree.c:2878
 handle_softirqs+0xba/0x290 kernel/softirq.c:579
 run_ksoftirqd+0x1c/0x30 kernel/softirq.c:968
 smpboot_thread_fn+0x32b/0x530 kernel/smpboot.c:160
 kthread+0x486/0x510 kernel/kthread.c:464
 ret_from_fork+0xdd/0x150 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff88811afa3278 of 8 bytes by task 3612 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:1322 [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+0x104/0x1c0 kernel/trace/bpf_trace.c:2298
 __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:4866
 skb_kfree_head net/core/skbuff.c:1047 [inline]
 skb_free_head+0xb8/0x150 net/core/skbuff.c:1059
 skb_release_data+0x33b/0x370 net/core/skbuff.c:1086
 skb_release_all net/core/skbuff.c:1151 [inline]
 __kfree_skb+0x44/0x150 net/core/skbuff.c:1165
 consume_skb+0x49/0x150 net/core/skbuff.c:1397
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:836 [inline]
 nsim_dev_trap_report_work+0x533/0x630 drivers/net/netdevsim/dev.c:866
 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+0x486/0x510 kernel/kthread.c:464
 ret_from_fork+0xdd/0x150 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0xffffffff844aeefb -> 0xffffffff81d4449b

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3612 Comm: kworker/u8:43 Not tainted 6.16.0-syzkaller-10355-gf2d282e1dfb3 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: events_unbound nsim_dev_trap_report_work
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