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BUG: KCSAN: data-race in __neigh_event_send / neigh_resolve_output

write to 0xffff8881554ad884 of 1 bytes by task 31813 on cpu 1:
 __neigh_event_send+0x3bd/0xa70 net/core/neighbour.c:1213
 neigh_event_send_probe include/net/neighbour.h:470 [inline]
 neigh_event_send include/net/neighbour.h:476 [inline]
 neigh_resolve_output+0x114/0x430 net/core/neighbour.c:1567
 neigh_output include/net/neighbour.h:546 [inline]
 ip_finish_output2+0x740/0x840 net/ipv4/ip_output.c:228
 ip_finish_output+0xf4/0x240 net/ipv4/ip_output.c:316
 NF_HOOK_COND include/linux/netfilter.h:291 [inline]
 ip_output+0xe5/0x1b0 net/ipv4/ip_output.c:430
 dst_output include/net/dst.h:444 [inline]
 ip_local_out+0x64/0x80 net/ipv4/ip_output.c:126
 iptunnel_xmit+0x34a/0x4b0 net/ipv4/ip_tunnel_core.c:82
 udp_tunnel_xmit_skb+0x182/0x1c0 net/ipv4/udp_tunnel_core.c:172
 send4+0x439/0x500 drivers/net/wireguard/socket.c:85
 wg_socket_send_skb_to_peer+0x94/0x130 drivers/net/wireguard/socket.c:175
 wg_socket_send_buffer_to_peer+0xd6/0x100 drivers/net/wireguard/socket.c:200
 wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline]
 wg_packet_handshake_send_worker+0x10c/0x150 drivers/net/wireguard/send.c:51
 process_one_work+0x3e6/0x750 kernel/workqueue.c:2390
 worker_thread+0x5f2/0xa10 kernel/workqueue.c:2537
 kthread+0x1ac/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308

read to 0xffff8881554ad884 of 1 bytes by task 2272 on cpu 0:
 neigh_event_send_probe include/net/neighbour.h:469 [inline]
 neigh_event_send include/net/neighbour.h:476 [inline]
 neigh_resolve_output+0x73/0x430 net/core/neighbour.c:1567
 neigh_output include/net/neighbour.h:546 [inline]
 ip_finish_output2+0x740/0x840 net/ipv4/ip_output.c:228
 ip_finish_output+0xf4/0x240 net/ipv4/ip_output.c:316
 NF_HOOK_COND include/linux/netfilter.h:291 [inline]
 ip_output+0xe5/0x1b0 net/ipv4/ip_output.c:430
 dst_output include/net/dst.h:444 [inline]
 ip_local_out+0x64/0x80 net/ipv4/ip_output.c:126
 iptunnel_xmit+0x34a/0x4b0 net/ipv4/ip_tunnel_core.c:82
 udp_tunnel_xmit_skb+0x182/0x1c0 net/ipv4/udp_tunnel_core.c:172
 send4+0x439/0x500 drivers/net/wireguard/socket.c:85
 wg_socket_send_skb_to_peer+0x94/0x130 drivers/net/wireguard/socket.c:175
 wg_socket_send_buffer_to_peer+0xd6/0x100 drivers/net/wireguard/socket.c:200
 wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline]
 wg_packet_handshake_send_worker+0x10c/0x150 drivers/net/wireguard/send.c:51
 process_one_work+0x3e6/0x750 kernel/workqueue.c:2390
 worker_thread+0x5f2/0xa10 kernel/workqueue.c:2537
 kthread+0x1ac/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308

value changed: 0x20 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 2272 Comm: kworker/u4:5 Tainted: G        W          6.3.0-rc1-syzkaller-00230-gef5f68cc1f82 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
Workqueue: wg-kex-wg1 wg_packet_handshake_send_worker
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