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BUG: KCSAN: data-race in __neigh_event_send / neigh_resolve_output

write to 0xffff88813084cc84 of 1 bytes by task 36 on cpu 0:
 __neigh_event_send+0x458/0xbc0 net/core/neighbour.c:1158
 neigh_event_send_probe include/net/neighbour.h:473 [inline]
 neigh_event_send include/net/neighbour.h:479 [inline]
 neigh_resolve_output+0x110/0x430 net/core/neighbour.c:1512
 neigh_output include/net/neighbour.h:549 [inline]
 ip_finish_output2+0x74d/0x850 net/ipv4/ip_output.c:228
 ip_finish_output+0xf3/0x250 net/ipv4/ip_output.c:316
 NF_HOOK_COND include/linux/netfilter.h:296 [inline]
 ip_output+0xf3/0x1a0 net/ipv4/ip_output.c:430
 dst_output include/net/dst.h:451 [inline]
 ip_local_out+0x60/0x80 net/ipv4/ip_output.c:126
 iptunnel_xmit+0x306/0x490 net/ipv4/ip_tunnel_core.c:82
 udp_tunnel_xmit_skb+0x15d/0x170 net/ipv4/udp_tunnel_core.c:171
 send4+0x439/0x500 drivers/net/wireguard/socket.c:85
 wg_socket_send_skb_to_peer+0x92/0x120 drivers/net/wireguard/socket.c:175
 wg_socket_send_buffer_to_peer+0xd2/0xf0 drivers/net/wireguard/socket.c:200
 wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline]
 wg_packet_handshake_send_worker+0x109/0x150 drivers/net/wireguard/send.c:51
 process_one_work+0x3d3/0x720 kernel/workqueue.c:2289
 worker_thread+0x618/0xa70 kernel/workqueue.c:2436
 kthread+0x1a9/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30

read to 0xffff88813084cc84 of 1 bytes by task 3137 on cpu 1:
 neigh_event_send_probe include/net/neighbour.h:472 [inline]
 neigh_event_send include/net/neighbour.h:479 [inline]
 neigh_resolve_output+0x6f/0x430 net/core/neighbour.c:1512
 neigh_output include/net/neighbour.h:549 [inline]
 ip_finish_output2+0x74d/0x850 net/ipv4/ip_output.c:228
 ip_finish_output+0xf3/0x250 net/ipv4/ip_output.c:316
 NF_HOOK_COND include/linux/netfilter.h:296 [inline]
 ip_output+0xf3/0x1a0 net/ipv4/ip_output.c:430
 dst_output include/net/dst.h:451 [inline]
 ip_local_out+0x60/0x80 net/ipv4/ip_output.c:126
 iptunnel_xmit+0x306/0x490 net/ipv4/ip_tunnel_core.c:82
 udp_tunnel_xmit_skb+0x15d/0x170 net/ipv4/udp_tunnel_core.c:171
 send4+0x439/0x500 drivers/net/wireguard/socket.c:85
 wg_socket_send_skb_to_peer+0x92/0x120 drivers/net/wireguard/socket.c:175
 wg_socket_send_buffer_to_peer+0xd2/0xf0 drivers/net/wireguard/socket.c:200
 wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline]
 wg_packet_handshake_send_worker+0x109/0x150 drivers/net/wireguard/send.c:51
 process_one_work+0x3d3/0x720 kernel/workqueue.c:2289
 worker_thread+0x618/0xa70 kernel/workqueue.c:2436
 kthread+0x1a9/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30

value changed: 0x20 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3137 Comm: kworker/u4:8 Not tainted 5.19.0-rc7-syzkaller-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022
Workqueue: wg-kex-wg1 wg_packet_handshake_send_worker
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