==================================================================
BUG: KCSAN: data-race in dst_cache_set_ip6 / fib6_clean_node

write to 0xffff8880379a842c of 4 bytes by task 9589 on cpu 0:
 fib6_clean_node+0xc0/0x260 net/ipv6/ip6_fib.c:2177
 fib6_walk_continue+0x38e/0x430 net/ipv6/ip6_fib.c:2111
 fib6_walk net/ipv6/ip6_fib.c:2159 [inline]
 fib6_clean_tree net/ipv6/ip6_fib.c:2239 [inline]
 __fib6_clean_all+0x188/0x2b0 net/ipv6/ip6_fib.c:2255
 fib6_flush_trees+0x6c/0x80 net/ipv6/ip6_fib.c:2280
 rt_genid_bump_ipv6 include/net/net_namespace.h:458 [inline]
 addrconf_dad_completed+0x57f/0x860 net/ipv6/addrconf.c:4205
 addrconf_dad_work+0x8dd/0x1150 net/ipv6/addrconf.c:3958
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2272
 worker_thread+0x635/0xb90 kernel/workqueue.c:2418
 kthread+0x1ff/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

read to 0xffff8880379a842c of 4 bytes by task 9744 on cpu 1:
 fib6_get_cookie_safe include/net/ip6_fib.h:283 [inline]
 rt6_get_cookie include/net/ip6_fib.h:304 [inline]
 dst_cache_set_ip6+0xd3/0x1e0 net/core/dst_cache.c:115
 send6+0x253/0x390 drivers/net/wireguard/socket.c:148
 wg_socket_send_skb_to_peer drivers/net/wireguard/socket.c:177 [inline]
 wg_socket_send_buffer_to_peer+0x167/0x1e0 drivers/net/wireguard/socket.c:199
 wg_packet_send_handshake_response+0xd8/0x130 drivers/net/wireguard/send.c:103
 wg_receive_handshake_packet drivers/net/wireguard/receive.c:161 [inline]
 wg_packet_handshake_receive_worker+0x2b8/0x460 drivers/net/wireguard/receive.c:220
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2272
 worker_thread+0x635/0xb90 kernel/workqueue.c:2418
 kthread+0x1ff/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 9744 Comm: kworker/1:4 Not tainted 5.9.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: wg-kex-wg0 wg_packet_handshake_receive_worker
==================================================================