syzbot

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BUG: KCSAN: data-race in __neigh_event_send / ip6_dst_lookup_tail

write to 0xffff888127ee9084 of 1 bytes by task 8875 on cpu 1:
 __neigh_event_send+0x40d/0xb20 net/core/neighbour.c:1157
 neigh_event_send include/net/neighbour.h:470 [inline]
 neigh_resolve_output+0x104/0x410 net/core/neighbour.c:1506
 neigh_output include/net/neighbour.h:541 [inline]
 ip6_finish_output2+0x9be/0xbd0 net/ipv6/ip6_output.c:126
 __ip6_finish_output net/ipv6/ip6_output.c:191 [inline]
 ip6_finish_output+0x446/0x4c0 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:451 [inline]
 ip6_local_out+0x60/0x80 net/ipv6/output_core.c:161
 ip6tunnel_xmit include/net/ip6_tunnel.h:161 [inline]
 udp_tunnel6_xmit_skb+0x31a/0x4d0 net/ipv6/ip6_udp_tunnel.c:109
 send6+0x2f1/0x3b0 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+0x3f6/0x960 kernel/workqueue.c:2307
 worker_thread+0x616/0xa70 kernel/workqueue.c:2454
 kthread+0x1bf/0x1e0 kernel/kthread.c:377
 ret_from_fork+0x1f/0x30

read to 0xffff888127ee9084 of 1 bytes by task 16716 on cpu 0:
 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+0x3f6/0x960 kernel/workqueue.c:2307
 worker_thread+0x616/0xa70 kernel/workqueue.c:2454
 kthread+0x1bf/0x1e0 kernel/kthread.c:377
 ret_from_fork+0x1f/0x30

value changed: 0x20 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 16716 Comm: kworker/u4:2 Not tainted 5.17.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: wg-kex-wg0 wg_packet_handshake_send_worker
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bond3: (slave bridge10): failed to get link speed/duplex
bond2: (slave bridge9): failed to get link speed/duplex
bond1: (slave bridge8): failed to get link speed/duplex
bond1: (slave bridge8): failed to get link speed/duplex
bond3: (slave bridge10): failed to get link speed/duplex
bond1: (slave bridge8): failed to get link speed/duplex
bond2: (slave bridge9): failed to get link speed/duplex