syzbot

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BUG: KCSAN: data-race in ip6_tnl_xmit / ip6_tnl_xmit

read to 0xffff8881322b71b0 of 8 bytes by task 21322 on cpu 0:
 ip6_tnl_xmit+0x56c/0x1620 net/ipv6/ip6_tunnel.c:1264
 ipxip6_tnl_xmit net/ipv6/ip6_tunnel.c:1381 [inline]
 ip6_tnl_start_xmit+0x941/0xa90 net/ipv6/ip6_tunnel.c:1430
 __netdev_start_xmit include/linux/netdevice.h:4987 [inline]
 netdev_start_xmit include/linux/netdevice.h:5001 [inline]
 xmit_one+0x105/0x2f0 net/core/dev.c:3590
 dev_hard_start_xmit net/core/dev.c:3606 [inline]
 __dev_queue_xmit+0x869/0xf70 net/core/dev.c:4226
 dev_queue_xmit+0x13/0x20 net/core/dev.c:4259
 neigh_connected_output+0x264/0x290 net/core/neighbour.c:1552
 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
 ip6_send_skb+0x43/0xf0 net/ipv6/ip6_output.c:1912
 udp_v6_send_skb+0x798/0x9f0 net/ipv6/udp.c:1249
 udpv6_sendmsg+0x1669/0x16e0 net/ipv6/udp.c:1547
 inet6_sendmsg+0x5f/0x80 net/ipv6/af_inet6.c:644
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg net/socket.c:724 [inline]
 ____sys_sendmsg+0x39a/0x510 net/socket.c:2409
 ___sys_sendmsg net/socket.c:2463 [inline]
 __sys_sendmmsg+0x267/0x4c0 net/socket.c:2549
 __do_sys_sendmmsg net/socket.c:2578 [inline]
 __se_sys_sendmmsg net/socket.c:2575 [inline]
 __x64_sys_sendmmsg+0x53/0x60 net/socket.c:2575
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

write to 0xffff8881322b71b0 of 8 bytes by task 21340 on cpu 1:
 ip6_tnl_xmit+0x57e/0x1620 net/ipv6/ip6_tunnel.c:1264
 ipxip6_tnl_xmit net/ipv6/ip6_tunnel.c:1381 [inline]
 ip6_tnl_start_xmit+0x941/0xa90 net/ipv6/ip6_tunnel.c:1430
 __netdev_start_xmit include/linux/netdevice.h:4987 [inline]
 netdev_start_xmit include/linux/netdevice.h:5001 [inline]
 xmit_one+0x105/0x2f0 net/core/dev.c:3590
 dev_hard_start_xmit net/core/dev.c:3606 [inline]
 __dev_queue_xmit+0x869/0xf70 net/core/dev.c:4226
 dev_queue_xmit+0x13/0x20 net/core/dev.c:4259
 neigh_connected_output+0x264/0x290 net/core/neighbour.c:1552
 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
 ip6_send_skb+0x43/0xf0 net/ipv6/ip6_output.c:1912
 udp_v6_send_skb+0x798/0x9f0 net/ipv6/udp.c:1249
 udpv6_sendmsg+0x1669/0x16e0 net/ipv6/udp.c:1547
 inet6_sendmsg+0x5f/0x80 net/ipv6/af_inet6.c:644
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg net/socket.c:724 [inline]
 ____sys_sendmsg+0x39a/0x510 net/socket.c:2409
 ___sys_sendmsg net/socket.c:2463 [inline]
 __sys_sendmmsg+0x267/0x4c0 net/socket.c:2549
 __do_sys_sendmmsg net/socket.c:2578 [inline]
 __se_sys_sendmmsg net/socket.c:2575 [inline]
 __x64_sys_sendmmsg+0x53/0x60 net/socket.c:2575
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000000bc1 -> 0x0000000000000bc2

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 21340 Comm: syz-executor.1 Not tainted 5.16.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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