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BUG: KCSAN: data-race in br_fdb_update / br_fdb_update

read to 0xffff8881047c11c0 of 8 bytes by interrupt on cpu 0:
 br_fdb_update+0x10e/0x480 net/bridge/br_fdb.c:910
 br_handle_frame_finish+0x32e/0xe70 net/bridge/br_input.c:141
 br_nf_pre_routing_finish+0x977/0xd70 net/bridge/br_netfilter_hooks.c:450
 NF_HOOK+0x19e/0x1e0 include/linux/netfilter.h:314
 br_nf_pre_routing+0xacf/0xbc0 net/bridge/br_netfilter_hooks.c:559
 nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline]
 nf_hook_bridge_pre net/bridge/br_input.c:277 [inline]
 br_handle_frame+0x4dd/0x9a0 net/bridge/br_input.c:424
 __netif_receive_skb_core+0xb00/0x2310 net/core/dev.c:5560
 __netif_receive_skb_one_core net/core/dev.c:5664 [inline]
 __netif_receive_skb+0x5a/0x280 net/core/dev.c:5779
 process_backlog+0x22e/0x440 net/core/dev.c:6111
 __napi_poll+0x63/0x3c0 net/core/dev.c:6775
 napi_poll net/core/dev.c:6844 [inline]
 net_rx_action+0x3a1/0x7f0 net/core/dev.c:6966
 handle_softirqs+0xbf/0x280 kernel/softirq.c:554
 run_ksoftirqd+0x1c/0x30 kernel/softirq.c:927
 smpboot_thread_fn+0x31c/0x4c0 kernel/smpboot.c:164
 kthread+0x1d1/0x210 kernel/kthread.c:389
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

write to 0xffff8881047c11c0 of 8 bytes by interrupt on cpu 1:
 br_fdb_update+0x142/0x480 net/bridge/br_fdb.c:911
 br_handle_frame_finish+0x32e/0xe70 net/bridge/br_input.c:141
 br_nf_hook_thresh+0x1e5/0x220
 br_nf_pre_routing_finish_ipv6+0x575/0x5a0
 NF_HOOK include/linux/netfilter.h:314 [inline]
 br_nf_pre_routing_ipv6+0x1f6/0x2a0 net/bridge/br_netfilter_ipv6.c:184
 br_nf_pre_routing+0x517/0xbc0 net/bridge/br_netfilter_hooks.c:533
 nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline]
 nf_hook_bridge_pre net/bridge/br_input.c:277 [inline]
 br_handle_frame+0x4dd/0x9a0 net/bridge/br_input.c:424
 __netif_receive_skb_core+0xb00/0x2310 net/core/dev.c:5560
 __netif_receive_skb_one_core net/core/dev.c:5664 [inline]
 __netif_receive_skb+0x5a/0x280 net/core/dev.c:5779
 process_backlog+0x22e/0x440 net/core/dev.c:6111
 __napi_poll+0x63/0x3c0 net/core/dev.c:6775
 napi_poll net/core/dev.c:6844 [inline]
 net_rx_action+0x3a1/0x7f0 net/core/dev.c:6966
 handle_softirqs+0xbf/0x280 kernel/softirq.c:554
 run_ksoftirqd+0x1c/0x30 kernel/softirq.c:927
 smpboot_thread_fn+0x31c/0x4c0 kernel/smpboot.c:164
 kthread+0x1d1/0x210 kernel/kthread.c:389
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

value changed: 0x00000000ffffe4f1 -> 0x00000000ffffe4f2

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 23 Comm: ksoftirqd/1 Tainted: G        W          6.12.0-rc5-syzkaller-00047-g4236f913808c #0
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
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