syzbot

IPv6: ADDRCONF(NETDEV_UP): team0: link is not ready
8021q: adding VLAN 0 to HW filter on device team0
IPv6: ADDRCONF(NETDEV_CHANGE): team0: link becomes ready

=============================
WARNING: suspicious RCU usage
4.17.0-rc1+ #16 Not tainted
-----------------------------
net/ipv6/route.c:1550 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
3 locks held by syz-executor0/4757:
 #0: 00000000a61192eb (rcu_read_lock_bh){....}, at: lwtunnel_xmit_redirect include/net/lwtunnel.h:92 [inline]
 #0: 00000000a61192eb (rcu_read_lock_bh){....}, at: ip6_finish_output2+0x253/0x2800 net/ipv6/ip6_output.c:106
 #1: 00000000a61192eb (rcu_read_lock_bh){....}, at: __dev_queue_xmit+0x30f/0x34c0 net/core/dev.c:3519
 #2: 0000000098dbd501 (rcu_read_lock){....}, at: ip6_link_failure+0xfe/0x790 net/ipv6/route.c:2227

stack backtrace:
CPU: 0 PID: 4757 Comm: syz-executor0 Not tainted 4.17.0-rc1+ #16
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1b9/0x294 lib/dump_stack.c:113
 lockdep_rcu_suspicious+0x14a/0x153 kernel/locking/lockdep.c:4592
 rt6_remove_exception_rt+0x416/0x4d0 net/ipv6/route.c:1549
 ip6_link_failure+0x484/0x790 net/ipv6/route.c:2231
 dst_link_failure include/net/dst.h:427 [inline]
 ip6_tnl_xmit+0x49a/0x34b0 net/ipv6/ip6_tunnel.c:1222
 ip6ip6_tnl_xmit net/ipv6/ip6_tunnel.c:1374 [inline]
 ip6_tnl_start_xmit+0x8fc/0x2290 net/ipv6/ip6_tunnel.c:1397
 __netdev_start_xmit include/linux/netdevice.h:4087 [inline]
 netdev_start_xmit include/linux/netdevice.h:4096 [inline]
 xmit_one net/core/dev.c:3054 [inline]
 dev_hard_start_xmit+0x264/0xc10 net/core/dev.c:3070
 __dev_queue_xmit+0x2724/0x34c0 net/core/dev.c:3585
 dev_queue_xmit+0x17/0x20 net/core/dev.c:3618
 neigh_direct_output+0x15/0x20 net/core/neighbour.c:1398
 neigh_output include/net/neighbour.h:482 [inline]
 ip6_finish_output2+0xc93/0x2800 net/ipv6/ip6_output.c:120
 ip6_finish_output+0x5fe/0xbc0 net/ipv6/ip6_output.c:154
 NF_HOOK_COND include/linux/netfilter.h:277 [inline]
 ip6_output+0x227/0x9b0 net/ipv6/ip6_output.c:171
 dst_output include/net/dst.h:444 [inline]
 NF_HOOK include/linux/netfilter.h:288 [inline]
 rawv6_send_hdrinc net/ipv6/raw.c:678 [inline]
 rawv6_sendmsg+0x2674/0x4590 net/ipv6/raw.c:924
 inet_sendmsg+0x19f/0x690 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:629 [inline]
 sock_sendmsg+0xd5/0x120 net/socket.c:639
 ___sys_sendmsg+0x805/0x940 net/socket.c:2117
 __sys_sendmsg+0x115/0x270 net/socket.c:2155
 __do_sys_sendmsg net/socket.c:2164 [inline]
 __se_sys_sendmsg net/socket.c:2162 [inline]
 __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2162
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x455389
RSP: 002b:00007ffcc085b9f8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000cec914 RCX: 0000000000455389
RDX: 0000000000000000 RSI: 0000000020000040 RDI: 0000000000000003
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R1