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BUG: KCSAN: data-race in ipip_tunnel_xmit / ipip_tunnel_xmit

write to 0xffff8880a301e130 of 8 bytes by task 3855 on cpu 0:
 ipip_tunnel_xmit+0x27f/0x300 net/ipv4/ipip.c:311
 __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+0xeb/0x420 net/core/dev.c:3486
 __dev_queue_xmit+0x14c4/0x1b80 net/core/dev.c:4063
 dev_queue_xmit+0x1e/0x30 net/core/dev.c:4096
 neigh_direct_output+0x1c/0x30 net/core/neighbour.c:1527
 neigh_output include/net/neighbour.h:510 [inline]
 ip6_finish_output2+0x717/0xf60 net/ipv6/ip6_output.c:116
 __ip6_finish_output net/ipv6/ip6_output.c:142 [inline]
 __ip6_finish_output+0x2cb/0x320 net/ipv6/ip6_output.c:127
 ip6_finish_output+0x3e/0x160 net/ipv6/ip6_output.c:152
 NF_HOOK_COND include/linux/netfilter.h:296 [inline]
 ip6_output+0x104/0x2a0 net/ipv6/ip6_output.c:175
 dst_output include/net/dst.h:436 [inline]
 ip6_local_out+0x70/0x90 net/ipv6/output_core.c:179
 ip6_send_skb+0x4f/0x110 net/ipv6/ip6_output.c:1795
 udp_v6_send_skb.isra.0+0x3f9/0xa80 net/ipv6/udp.c:1172
 udpv6_sendmsg+0x19e1/0x1d40 net/ipv6/udp.c:1470
 inet6_sendmsg+0x69/0x90 net/ipv6/af_inet6.c:576
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0x98/0xc0 net/socket.c:672
 ____sys_sendmsg+0x207/0x4c0 net/socket.c:2343
 ___sys_sendmsg+0xb5/0x100 net/socket.c:2397
 __sys_sendmmsg+0x10e/0x310 net/socket.c:2487
 __do_sys_sendmmsg net/socket.c:2516 [inline]
 __se_sys_sendmmsg net/socket.c:2513 [inline]
 __x64_sys_sendmmsg+0x60/0x80 net/socket.c:2513
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880a301e130 of 8 bytes by task 3865 on cpu 1:
 ipip_tunnel_xmit+0x26b/0x300 net/ipv4/ipip.c:311
 __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+0xeb/0x420 net/core/dev.c:3486
 __dev_queue_xmit+0x14c4/0x1b80 net/core/dev.c:4063
 dev_queue_xmit+0x1e/0x30 net/core/dev.c:4096
 neigh_direct_output+0x1c/0x30 net/core/neighbour.c:1527
 neigh_output include/net/neighbour.h:510 [inline]
 ip6_finish_output2+0x717/0xf60 net/ipv6/ip6_output.c:116
 __ip6_finish_output net/ipv6/ip6_output.c:142 [inline]
 __ip6_finish_output+0x2cb/0x320 net/ipv6/ip6_output.c:127
 ip6_finish_output+0x3e/0x160 net/ipv6/ip6_output.c:152
 NF_HOOK_COND include/linux/netfilter.h:296 [inline]
 ip6_output+0x104/0x2a0 net/ipv6/ip6_output.c:175
 dst_output include/net/dst.h:436 [inline]
 ip6_local_out+0x70/0x90 net/ipv6/output_core.c:179
 ip6_send_skb+0x4f/0x110 net/ipv6/ip6_output.c:1795
 udp_v6_send_skb.isra.0+0x3f9/0xa80 net/ipv6/udp.c:1172
 udpv6_sendmsg+0x19e1/0x1d40 net/ipv6/udp.c:1470
 inet6_sendmsg+0x69/0x90 net/ipv6/af_inet6.c:576
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0x98/0xc0 net/socket.c:672
 ____sys_sendmsg+0x207/0x4c0 net/socket.c:2343
 ___sys_sendmsg+0xb5/0x100 net/socket.c:2397
 __sys_sendmmsg+0x10e/0x310 net/socket.c:2487
 __do_sys_sendmmsg net/socket.c:2516 [inline]
 __se_sys_sendmmsg net/socket.c:2513 [inline]
 __x64_sys_sendmmsg+0x60/0x80 net/socket.c:2513
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3865 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
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