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BUG: KCSAN: data-race in __bpf_get_stackid / bcmp

write to 0xffff888112829f78 of 136 bytes by task 10076 on cpu 1:
 __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_run3+0x10f/0x1d0 kernel/trace/bpf_trace.c:2299
 __do_trace_kmem_cache_free include/trace/events/kmem.h:114 [inline]
 trace_kmem_cache_free include/trace/events/kmem.h:114 [inline]
 kmem_cache_free+0x257/0x300 mm/slub.c:4796
 skb_kfree_head net/core/skbuff.c:1045 [inline]
 skb_free_head+0x87/0x150 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
 netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline]
 netlink_unicast+0x5c8/0x690 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x58b/0x6b0 net/netlink/af_netlink.c:1896
 sock_sendmsg_nosec net/socket.c:714 [inline]
 __sock_sendmsg+0x142/0x180 net/socket.c:729
 ____sys_sendmsg+0x31e/0x4e0 net/socket.c:2614
 ___sys_sendmsg+0x17b/0x1d0 net/socket.c:2668
 __sys_sendmsg net/socket.c:2700 [inline]
 __do_sys_sendmsg net/socket.c:2705 [inline]
 __se_sys_sendmsg net/socket.c:2703 [inline]
 __x64_sys_sendmsg+0xd4/0x160 net/socket.c:2703
 x64_sys_call+0x191e/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:47
 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 0xffff888112829fa8 of 8 bytes by task 10074 on cpu 0:
 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_run3+0x10f/0x1d0 kernel/trace/bpf_trace.c:2299
 __do_trace_kmem_cache_free include/trace/events/kmem.h:114 [inline]
 trace_kmem_cache_free include/trace/events/kmem.h:114 [inline]
 kmem_cache_free+0x257/0x300 mm/slub.c:4796
 kfree_skbmem net/core/skbuff.c:-1 [inline]
 __kfree_skb+0x109/0x150 net/core/skbuff.c:1166
 sk_skb_reason_drop+0xbd/0x270 net/core/skbuff.c:1203
 tcp_v6_rcv+0x18e/0x1d60 net/ipv6/tcp_ipv6.c:1947
 ip6_protocol_deliver_rcu+0xa17/0x10d0 net/ipv6/ip6_input.c:438
 ip6_input_finish+0xf0/0x1d0 net/ipv6/ip6_input.c:489
 NF_HOOK include/linux/netfilter.h:318 [inline]
 ip6_input+0x5e/0x140 net/ipv6/ip6_input.c:500
 dst_input include/net/dst.h:471 [inline]
 ip6_sublist_rcv_finish net/ipv6/ip6_input.c:88 [inline]
 ip6_list_rcv_finish net/ipv6/ip6_input.c:145 [inline]
 ip6_sublist_rcv+0x924/0xa40 net/ipv6/ip6_input.c:321
 ipv6_list_rcv+0x267/0x2a0 net/ipv6/ip6_input.c:355
 __netif_receive_skb_list_ptype net/core/dev.c:6034 [inline]
 __netif_receive_skb_list_core+0x3b0/0x500 net/core/dev.c:6081
 __netif_receive_skb_list net/core/dev.c:6133 [inline]
 netif_receive_skb_list_internal+0x487/0x600 net/core/dev.c:6224
 netif_receive_skb_list+0x31/0x200 net/core/dev.c:6276
 xdp_recv_frames net/bpf/test_run.c:280 [inline]
 xdp_test_run_batch net/bpf/test_run.c:361 [inline]
 bpf_test_run_xdp_live+0xdcb/0xfe0 net/bpf/test_run.c:390
 bpf_prog_test_run_xdp+0x4f5/0x910 net/bpf/test_run.c:1322
 bpf_prog_test_run+0x22a/0x390 kernel/bpf/syscall.c:4590
 __sys_bpf+0x4b9/0x7b0 kernel/bpf/syscall.c:6047
 __do_sys_bpf kernel/bpf/syscall.c:6139 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:6137 [inline]
 __x64_sys_bpf+0x41/0x50 kernel/bpf/syscall.c:6137
 x64_sys_call+0x2aea/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:322
 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

value changed: 0xffffffff84c2c38e -> 0xffffffff844c4ae4

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 10074 Comm: syz.5.13970 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
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