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

read to 0xffff888150746150 of 8 bytes by task 3456 on cpu 1:
 ip_tunnel_xmit+0x99d/0x11b0 net/ipv4/ip_tunnel.c:819
 sit_tunnel_xmit__ net/ipv6/sit.c:1065 [inline]
 sit_tunnel_xmit+0x3d3/0x1200 net/ipv6/sit.c:1081
 __netdev_start_xmit include/linux/netdevice.h:4988 [inline]
 netdev_start_xmit include/linux/netdevice.h:5002 [inline]
 xmit_one+0xf9/0x270 net/core/dev.c:3576
 dev_hard_start_xmit net/core/dev.c:3592 [inline]
 __dev_queue_xmit+0x6e9/0xaa0 net/core/dev.c:4202
 dev_queue_xmit+0x13/0x20 net/core/dev.c:4235
 neigh_connected_output+0x264/0x290 net/core/neighbour.c:1521
 neigh_output include/net/neighbour.h:510 [inline]
 ip_finish_output2+0x80a/0xaa0 net/ipv4/ip_output.c:221
 ip_finish_output+0x3b5/0x510 net/ipv4/ip_output.c:309
 NF_HOOK_COND include/linux/netfilter.h:296 [inline]
 ip_mc_output+0x2a7/0x350 net/ipv4/ip_output.c:408
 dst_output include/net/dst.h:450 [inline]
 ip_local_out+0x164/0x220 net/ipv4/ip_output.c:126
 ip_send_skb+0x27/0x90 net/ipv4/ip_output.c:1555
 udp_send_skb+0x62d/0x860 net/ipv4/udp.c:967
 udp_sendmsg+0x1257/0x1320 net/ipv4/udp.c:1254
 udpv6_sendmsg+0x6a3/0x16e0
 inet6_sendmsg+0x5f/0x80 net/ipv6/af_inet6.c:643
 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+0x388/0x520 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+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

write to 0xffff888150746150 of 8 bytes by task 2679 on cpu 0:
 ip_tunnel_xmit+0x9af/0x11b0 net/ipv4/ip_tunnel.c:819
 sit_tunnel_xmit__ net/ipv6/sit.c:1065 [inline]
 sit_tunnel_xmit+0x3d3/0x1200 net/ipv6/sit.c:1081
 __netdev_start_xmit include/linux/netdevice.h:4988 [inline]
 netdev_start_xmit include/linux/netdevice.h:5002 [inline]
 xmit_one+0xf9/0x270 net/core/dev.c:3576
 dev_hard_start_xmit net/core/dev.c:3592 [inline]
 __dev_queue_xmit+0x6e9/0xaa0 net/core/dev.c:4202
 dev_queue_xmit+0x13/0x20 net/core/dev.c:4235
 neigh_connected_output+0x264/0x290 net/core/neighbour.c:1521
 neigh_output include/net/neighbour.h:510 [inline]
 ip_finish_output2+0x80a/0xaa0 net/ipv4/ip_output.c:221
 ip_finish_output+0x3b5/0x510 net/ipv4/ip_output.c:309
 NF_HOOK_COND include/linux/netfilter.h:296 [inline]
 ip_mc_output+0x2a7/0x350 net/ipv4/ip_output.c:408
 dst_output include/net/dst.h:450 [inline]
 ip_local_out+0x164/0x220 net/ipv4/ip_output.c:126
 ip_send_skb+0x27/0x90 net/ipv4/ip_output.c:1555
 udp_send_skb+0x62d/0x860 net/ipv4/udp.c:967
 udp_sendmsg+0x1257/0x1320 net/ipv4/udp.c:1254
 udpv6_sendmsg+0x6a3/0x16e0
 inet6_sendmsg+0x5f/0x80 net/ipv6/af_inet6.c:643
 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+0x388/0x520 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+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x000000000003201f -> 0x0000000000032020

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 2679 Comm: syz-executor.0 Not tainted 5.15.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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syz-executor.0 (2679) used greatest stack depth: 9760 bytes left