================================================================== BUG: KCSAN: data-race in __neigh_event_send / ip6_finish_output2 write to 0xffff888027123485 of 1 bytes by task 24 on cpu 1: __neigh_event_send+0x40c/0xad0 net/core/neighbour.c:1128 neigh_event_send include/net/neighbour.h:444 [inline] neigh_resolve_output+0x104/0x410 net/core/neighbour.c:1476 neigh_output include/net/neighbour.h:510 [inline] ip6_finish_output2+0x985/0xb20 net/ipv6/ip6_output.c:117 __ip6_finish_output+0x428/0x480 net/ipv6/ip6_output.c:182 ip6_finish_output+0x39/0x160 net/ipv6/ip6_output.c:192 NF_HOOK_COND include/linux/netfilter.h:290 [inline] ip6_output+0x10e/0x210 net/ipv6/ip6_output.c:215 dst_output include/net/dst.h:441 [inline] ip6_local_out+0x60/0x80 net/ipv6/output_core.c:179 ip6tunnel_xmit include/net/ip6_tunnel.h:160 [inline] udp_tunnel6_xmit_skb+0x2f9/0x490 net/ipv6/ip6_udp_tunnel.c:109 send6+0x2d8/0x3a0 drivers/net/wireguard/socket.c:152 wg_socket_send_skb_to_peer drivers/net/wireguard/socket.c:177 [inline] wg_socket_send_buffer_to_peer+0x186/0x210 drivers/net/wireguard/socket.c:199 wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline] wg_packet_handshake_send_worker+0xf9/0x140 drivers/net/wireguard/send.c:51 process_one_work+0x3e1/0x950 kernel/workqueue.c:2275 worker_thread+0x616/0xa70 kernel/workqueue.c:2421 kthread+0x20b/0x230 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 read to 0xffff888027123485 of 1 bytes by task 19665 on cpu 0: neigh_output include/net/neighbour.h:507 [inline] ip6_finish_output2+0x6f9/0xb20 net/ipv6/ip6_output.c:117 __ip6_finish_output+0x428/0x480 net/ipv6/ip6_output.c:182 ip6_finish_output+0x39/0x160 net/ipv6/ip6_output.c:192 NF_HOOK_COND include/linux/netfilter.h:290 [inline] ip6_output+0x10e/0x210 net/ipv6/ip6_output.c:215 dst_output include/net/dst.h:441 [inline] ip6_local_out+0x60/0x80 net/ipv6/output_core.c:179 ip6tunnel_xmit include/net/ip6_tunnel.h:160 [inline] udp_tunnel6_xmit_skb+0x2f9/0x490 net/ipv6/ip6_udp_tunnel.c:109 send6+0x2d8/0x3a0 drivers/net/wireguard/socket.c:152 wg_socket_send_skb_to_peer drivers/net/wireguard/socket.c:177 [inline] wg_socket_send_buffer_to_peer+0x186/0x210 drivers/net/wireguard/socket.c:199 wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline] wg_packet_handshake_send_worker+0xf9/0x140 drivers/net/wireguard/send.c:51 process_one_work+0x3e1/0x950 kernel/workqueue.c:2275 worker_thread+0x616/0xa70 kernel/workqueue.c:2421 kthread+0x20b/0x230 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 19665 Comm: kworker/u4:5 Not tainted 5.11.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: wg-kex-wg2 wg_packet_handshake_send_worker ==================================================================