==================================================================
BUG: KCSAN: data-race in ip6_tnl_start_xmit / ip6_tnl_start_xmit

write to 0xffff8880b334f140 of 8 bytes by task 12265 on cpu 0:
 ip6_tnl_start_xmit+0x449/0x1160 net/ipv6/ip6_tunnel.c:1415
 __netdev_start_xmit include/linux/netdevice.h:4510 [inline]
 netdev_start_xmit include/linux/netdevice.h:4524 [inline]
 xmit_one net/core/dev.c:3470 [inline]
 dev_hard_start_xmit+0xef/0x430 net/core/dev.c:3486
 __dev_queue_xmit+0x14e9/0x1ba0 net/core/dev.c:4063
 dev_queue_xmit+0x21/0x30 net/core/dev.c:4096
 neigh_direct_output+0x1f/0x30 net/core/neighbour.c:1527
 neigh_output include/net/neighbour.h:510 [inline]
 ip_finish_output2+0x408/0xea0 net/ipv4/ip_output.c:228
 __ip_finish_output net/ipv4/ip_output.c:306 [inline]
 __ip_finish_output+0x23a/0x4b0 net/ipv4/ip_output.c:288
 ip_finish_output+0x41/0x160 net/ipv4/ip_output.c:316
 NF_HOOK_COND include/linux/netfilter.h:296 [inline]
 ip_mc_output+0x143/0x620 net/ipv4/ip_output.c:415
 dst_output include/net/dst.h:436 [inline]
 ip_local_out+0x74/0x90 net/ipv4/ip_output.c:125
 ip_send_skb+0x35/0xb0 net/ipv4/ip_output.c:1560
 udp_send_skb.isra.0+0x3d1/0x8c0 net/ipv4/udp.c:891
 udp_sendmsg+0x1589/0x1930 net/ipv4/udp.c:1178
 udpv6_sendmsg+0xe75/0x1d40 net/ipv6/udp.c:1283
 inet6_sendmsg+0x6d/0x90 net/ipv6/af_inet6.c:576
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0x9f/0xc0 net/socket.c:672
 ____sys_sendmsg+0x212/0x4d0 net/socket.c:2343
 ___sys_sendmsg+0xb5/0x100 net/socket.c:2397
 __sys_sendmmsg+0x123/0x350 net/socket.c:2487
 __do_sys_sendmmsg net/socket.c:2516 [inline]
 __se_sys_sendmmsg net/socket.c:2513 [inline]
 __x64_sys_sendmmsg+0x64/0x80 net/socket.c:2513
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880b334f140 of 8 bytes by task 12282 on cpu 1:
 ip6_tnl_start_xmit+0x436/0x1160 net/ipv6/ip6_tunnel.c:1415
 __netdev_start_xmit include/linux/netdevice.h:4510 [inline]
 netdev_start_xmit include/linux/netdevice.h:4524 [inline]
 xmit_one net/core/dev.c:3470 [inline]
 dev_hard_start_xmit+0xef/0x430 net/core/dev.c:3486
 __dev_queue_xmit+0x14e9/0x1ba0 net/core/dev.c:4063
 dev_queue_xmit+0x21/0x30 net/core/dev.c:4096
 neigh_direct_output+0x1f/0x30 net/core/neighbour.c:1527
 neigh_output include/net/neighbour.h:510 [inline]
 ip_finish_output2+0x408/0xea0 net/ipv4/ip_output.c:228
 __ip_finish_output net/ipv4/ip_output.c:306 [inline]
 __ip_finish_output+0x23a/0x4b0 net/ipv4/ip_output.c:288
 ip_finish_output+0x41/0x160 net/ipv4/ip_output.c:316
 NF_HOOK_COND include/linux/netfilter.h:296 [inline]
 ip_mc_output+0x143/0x620 net/ipv4/ip_output.c:415
 dst_output include/net/dst.h:436 [inline]
 ip_local_out+0x74/0x90 net/ipv4/ip_output.c:125
 ip_send_skb+0x35/0xb0 net/ipv4/ip_output.c:1560
 udp_send_skb.isra.0+0x3d1/0x8c0 net/ipv4/udp.c:891
 udp_sendmsg+0x1589/0x1930 net/ipv4/udp.c:1178
 udpv6_sendmsg+0xe75/0x1d40 net/ipv6/udp.c:1283
 inet6_sendmsg+0x6d/0x90 net/ipv6/af_inet6.c:576
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0x9f/0xc0 net/socket.c:672
 ____sys_sendmsg+0x212/0x4d0 net/socket.c:2343
 ___sys_sendmsg+0xb5/0x100 net/socket.c:2397
 __sys_sendmmsg+0x123/0x350 net/socket.c:2487
 __do_sys_sendmmsg net/socket.c:2516 [inline]
 __se_sys_sendmmsg net/socket.c:2513 [inline]
 __x64_sys_sendmmsg+0x64/0x80 net/socket.c:2513
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 12282 Comm: syz-executor.1 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================