syzbot

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BUG: KCSAN: data-race in ip6gre_tunnel_xmit / ip6gre_tunnel_xmit

write to 0xffff8880a5c19130 of 8 bytes by task 15001 on cpu 0:
 ip6gre_tunnel_xmit+0x39b/0x8c0 net/ipv6/ip6_gre.c:906
 __netdev_start_xmit include/linux/netdevice.h:4510 [inline]
 netdev_start_xmit include/linux/netdevice.h:4524 [inline]
 dev_direct_xmit+0x283/0x390 net/core/dev.c:4129
 packet_direct_xmit+0xe3/0x140 net/packet/af_packet.c:240
 packet_snd net/packet/af_packet.c:2967 [inline]
 packet_sendmsg+0x1ec1/0x3b40 net/packet/af_packet.c:2992
 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 0xffff8880a5c19130 of 8 bytes by task 15009 on cpu 1:
 ip6gre_tunnel_xmit+0x381/0x8c0 net/ipv6/ip6_gre.c:906
 __netdev_start_xmit include/linux/netdevice.h:4510 [inline]
 netdev_start_xmit include/linux/netdevice.h:4524 [inline]
 dev_direct_xmit+0x283/0x390 net/core/dev.c:4129
 packet_direct_xmit+0xe3/0x140 net/packet/af_packet.c:240
 packet_snd net/packet/af_packet.c:2967 [inline]
 packet_sendmsg+0x1ec1/0x3b40 net/packet/af_packet.c:2992
 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: 15009 Comm: syz-executor.2 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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