syzbot

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BUG: KCSAN: data-race in ip_tunnel_xmit / sit_tunnel_xmit

write to 0xffff88812cf8b150 of 8 bytes by task 20569 on cpu 0:
 ip_tunnel_xmit+0xdd2/0x11c0 net/ipv4/ip_tunnel.c:813
 sit_tunnel_xmit__ net/ipv6/sit.c:1061 [inline]
 sit_tunnel_xmit+0x3c2/0x11f0 net/ipv6/sit.c:1077
 __netdev_start_xmit include/linux/netdevice.h:4944 [inline]
 netdev_start_xmit include/linux/netdevice.h:4958 [inline]
 xmit_one+0xf9/0x270 net/core/dev.c:3654
 dev_hard_start_xmit net/core/dev.c:3670 [inline]
 __dev_queue_xmit+0xcda/0x12a0 net/core/dev.c:4246
 dev_queue_xmit+0x13/0x20 net/core/dev.c:4279
 neigh_connected_output+0x264/0x290 net/core/neighbour.c:1524
 neigh_output include/net/neighbour.h:510 [inline]
 ip_finish_output2+0x874/0xb10 net/ipv4/ip_output.c:230
 __ip_finish_output net/ipv4/ip_output.c:252 [inline]
 ip_finish_output+0x2fa/0x490 net/ipv4/ip_output.c:318
 NF_HOOK_COND include/linux/netfilter.h:290 [inline]
 ip_mc_output+0x4b1/0x670 net/ipv4/ip_output.c:417
 dst_output include/net/dst.h:448 [inline]
 ip_local_out+0x167/0x230 net/ipv4/ip_output.c:126
 ip_send_skb+0x27/0x90 net/ipv4/ip_output.c:1568
 udp_send_skb+0x62d/0x860 net/ipv4/udp.c:953
 udp_sendmsg+0xfe4/0x12f0 net/ipv4/udp.c:1240
 udpv6_sendmsg+0x520/0x16b0 net/ipv6/udp.c:1351
 inet6_sendmsg+0x5f/0x80 net/ipv6/af_inet6.c:642
 sock_sendmsg_nosec net/socket.c:654 [inline]
 sock_sendmsg net/socket.c:674 [inline]
 ____sys_sendmsg+0x360/0x4d0 net/socket.c:2350
 ___sys_sendmsg net/socket.c:2404 [inline]
 __sys_sendmmsg+0x315/0x4b0 net/socket.c:2490
 __do_sys_sendmmsg net/socket.c:2519 [inline]
 __se_sys_sendmmsg net/socket.c:2516 [inline]
 __x64_sys_sendmmsg+0x53/0x60 net/socket.c:2516
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88812cf8b150 of 8 bytes by task 20603 on cpu 1:
 sit_tunnel_xmit+0x9d4/0x11f0 include/net/dst.h:426
 __netdev_start_xmit include/linux/netdevice.h:4944 [inline]
 netdev_start_xmit include/linux/netdevice.h:4958 [inline]
 xmit_one+0xf9/0x270 net/core/dev.c:3654
 dev_hard_start_xmit net/core/dev.c:3670 [inline]
 __dev_queue_xmit+0xcda/0x12a0 net/core/dev.c:4246
 dev_queue_xmit+0x13/0x20 net/core/dev.c:4279
 neigh_connected_output+0x264/0x290 net/core/neighbour.c:1524
 neigh_output include/net/neighbour.h:510 [inline]
 ip6_finish_output2+0x8f5/0xa80 net/ipv6/ip6_output.c:117
 __ip6_finish_output net/ipv6/ip6_output.c:182 [inline]
 ip6_finish_output+0x428/0x480 net/ipv6/ip6_output.c:192
 NF_HOOK_COND include/linux/netfilter.h:290 [inline]
 ip6_output+0x10e/0x210 net/ipv6/ip6_output.c:215
 dst_output include/net/dst.h:448 [inline]
 ip6_local_out+0x124/0x1e0 net/ipv6/output_core.c:179
 ip6_send_skb+0x43/0xf0 net/ipv6/ip6_output.c:1904
 udp_v6_send_skb+0x798/0x9f0 net/ipv6/udp.c:1235
 udpv6_sendmsg+0x163c/0x16b0 net/ipv6/udp.c:1533
 inet6_sendmsg+0x5f/0x80 net/ipv6/af_inet6.c:642
 sock_sendmsg_nosec net/socket.c:654 [inline]
 sock_sendmsg net/socket.c:674 [inline]
 ____sys_sendmsg+0x360/0x4d0 net/socket.c:2350
 ___sys_sendmsg net/socket.c:2404 [inline]
 __sys_sendmmsg+0x315/0x4b0 net/socket.c:2490
 __do_sys_sendmmsg net/socket.c:2519 [inline]
 __se_sys_sendmmsg net/socket.c:2516 [inline]
 __x64_sys_sendmmsg+0x53/0x60 net/socket.c:2516
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000000000457a3 -> 0x00000000000457a4

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 20603 Comm: syz-executor.1 Not tainted 5.13.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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