==================================================================
BUG: KCSAN: data-race in __neigh_event_send / ip6_dst_lookup_tail

write to 0xffff88813b41fe84 of 1 bytes by task 24097 on cpu 0:
 __neigh_event_send+0x409/0xb10 net/core/neighbour.c:1158
 neigh_event_send include/net/neighbour.h:456 [inline]
 neigh_resolve_output+0x104/0x410 net/core/neighbour.c:1507
 neigh_output include/net/neighbour.h:527 [inline]
 ip6_finish_output2+0x9be/0xbb0 net/ipv6/ip6_output.c:126
 __ip6_finish_output net/ipv6/ip6_output.c:191 [inline]
 ip6_finish_output+0x444/0x4c0 net/ipv6/ip6_output.c:201
 NF_HOOK_COND include/linux/netfilter.h:296 [inline]
 ip6_output+0x10e/0x210 net/ipv6/ip6_output.c:224
 dst_output include/net/dst.h:450 [inline]
 ip6_local_out+0x60/0x80 net/ipv6/output_core.c:161
 ip6tunnel_xmit include/net/ip6_tunnel.h:160 [inline]
 udp_tunnel6_xmit_skb+0x31a/0x4d0 net/ipv6/ip6_udp_tunnel.c:109
 send6+0x2ef/0x3b0 drivers/net/wireguard/socket.c:152
 wg_socket_send_skb_to_peer+0xbb/0x130 drivers/net/wireguard/socket.c:177
 wg_socket_send_buffer_to_peer+0xf7/0x120 drivers/net/wireguard/socket.c:199
 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+0x3fc/0x980 kernel/workqueue.c:2298
 worker_thread+0x616/0xa70 kernel/workqueue.c:2445
 kthread+0x2c7/0x2e0 kernel/kthread.c:327
 ret_from_fork+0x1f/0x30

read to 0xffff88813b41fe84 of 1 bytes by task 1857 on cpu 1:
 ip6_dst_lookup_tail+0x660/0x920 net/ipv6/ip6_output.c:1116
 ip6_dst_lookup_flow+0x44/0xc0 net/ipv6/ip6_output.c:1200
 send6+0x238/0x3b0 drivers/net/wireguard/socket.c:139
 wg_socket_send_skb_to_peer+0xbb/0x130 drivers/net/wireguard/socket.c:177
 wg_socket_send_buffer_to_peer+0xf7/0x120 drivers/net/wireguard/socket.c:199
 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+0x3fc/0x980 kernel/workqueue.c:2298
 worker_thread+0x616/0xa70 kernel/workqueue.c:2445
 kthread+0x2c7/0x2e0 kernel/kthread.c:327
 ret_from_fork+0x1f/0x30

value changed: 0x20 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 1857 Comm: kworker/u4:4 Not tainted 5.16.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: wg-kex-wg1 wg_packet_handshake_send_worker
==================================================================