KCSAN: data-race in ip6_tnl_xmit / ip6_tnl

KCSAN: data-race in ip6_tnl_xmit / ip6_tnl_xmit (3)
Status: auto-closed as invalid on 2021/03/18 08:19
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 224d, last: 224d

similar bugs (2):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in ip6_tnl_xmit / ip6_tnl_xmit				3	693d	697d	0/22	closed as invalid on 2019/11/19 13:24
upstream	KCSAN: data-race in ip6_tnl_xmit / ip6_tnl_xmit (2)				1	364d	364d	0/22	auto-closed as invalid on 2020/10/29 08:32

Sample crash report:

==================================================================
BUG: KCSAN: data-race in ip6_tnl_xmit / ip6_tnl_xmit

write to 0xffff88802a9e3190 of 8 bytes by task 13459 on cpu 1:
 ip6_tnl_xmit+0x7aa/0x1570 net/ipv6/ip6_tunnel.c:1266
 ipxip6_tnl_xmit net/ipv6/ip6_tunnel.c:1381 [inline]
 ip6_tnl_start_xmit+0x8af/0x9f0 net/ipv6/ip6_tunnel.c:1430
 __netdev_start_xmit include/linux/netdevice.h:4778 [inline]
 netdev_start_xmit include/linux/netdevice.h:4792 [inline]
 xmit_one+0xf9/0x2e0 net/core/dev.c:3574
 dev_hard_start_xmit net/core/dev.c:3590 [inline]
 __dev_queue_xmit+0xf22/0x1570 net/core/dev.c:4151
 dev_queue_xmit+0x13/0x20 net/core/dev.c:4184
 neigh_connected_output+0x264/0x290 net/core/neighbour.c:1521
 neigh_output include/net/neighbour.h:510 [inline]
 ip6_finish_output2+0x985/0xb20 net/ipv6/ip6_output.c:117
 __ip6_finish_output+0x428/0x480 net/ipv6/ip6_output.c:182
 ip6_finish_output+0x39/0x160 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:441 [inline]
 ip6_local_out+0x60/0x80 net/ipv6/output_core.c:179
 ip6_send_skb net/ipv6/ip6_output.c:1904 [inline]
 ip6_push_pending_frames+0xb6/0x170 net/ipv6/ip6_output.c:1924
 rawv6_push_pending_frames net/ipv6/raw.c:613 [inline]
 rawv6_sendmsg+0x128c/0x1330 net/ipv6/raw.c:956
 inet_sendmsg+0x5f/0x80 net/ipv4/af_inet.c:817
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg net/socket.c:672 [inline]
 ____sys_sendmsg+0x360/0x4d0 net/socket.c:2345
 ___sys_sendmsg net/socket.c:2399 [inline]
 __sys_sendmmsg+0x335/0x4b0 net/socket.c:2489
 __do_sys_sendmmsg net/socket.c:2518 [inline]
 __se_sys_sendmmsg net/socket.c:2515 [inline]
 __x64_sys_sendmmsg+0x53/0x60 net/socket.c:2515
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88802a9e3190 of 8 bytes by task 13445 on cpu 0:
 ip6_tnl_xmit+0x798/0x1570 net/ipv6/ip6_tunnel.c:1266
 ipxip6_tnl_xmit net/ipv6/ip6_tunnel.c:1381 [inline]
 ip6_tnl_start_xmit+0x8af/0x9f0 net/ipv6/ip6_tunnel.c:1430
 __netdev_start_xmit include/linux/netdevice.h:4778 [inline]
 netdev_start_xmit include/linux/netdevice.h:4792 [inline]
 xmit_one+0xf9/0x2e0 net/core/dev.c:3574
 dev_hard_start_xmit net/core/dev.c:3590 [inline]
 __dev_queue_xmit+0xf22/0x1570 net/core/dev.c:4151
 dev_queue_xmit+0x13/0x20 net/core/dev.c:4184
 neigh_connected_output+0x264/0x290 net/core/neighbour.c:1521
 neigh_output include/net/neighbour.h:510 [inline]
 ip6_finish_output2+0x985/0xb20 net/ipv6/ip6_output.c:117
 __ip6_finish_output+0x428/0x480 net/ipv6/ip6_output.c:182
 ip6_finish_output+0x39/0x160 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:441 [inline]
 ip6_local_out+0x60/0x80 net/ipv6/output_core.c:179
 ip6_send_skb net/ipv6/ip6_output.c:1904 [inline]
 ip6_push_pending_frames+0xb6/0x170 net/ipv6/ip6_output.c:1924
 rawv6_push_pending_frames net/ipv6/raw.c:613 [inline]
 rawv6_sendmsg+0x128c/0x1330 net/ipv6/raw.c:956
 inet_sendmsg+0x5f/0x80 net/ipv4/af_inet.c:817
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg net/socket.c:672 [inline]
 ____sys_sendmsg+0x360/0x4d0 net/socket.c:2345
 ___sys_sendmsg net/socket.c:2399 [inline]
 __sys_sendmmsg+0x335/0x4b0 net/socket.c:2489
 __do_sys_sendmmsg net/socket.c:2518 [inline]
 __se_sys_sendmmsg net/socket.c:2515 [inline]
 __x64_sys_sendmmsg+0x53/0x60 net/socket.c:2515
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 13445 Comm: syz-executor.0 Not tainted 5.11.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (1):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci2-upstream-kcsan-gce	2021/02/11 08:09	upstream	291009f656e8	a52ee10a	.config	log	report			info	KCSAN: data-race in ip6_tnl_xmit / ip6_tnl_xmit