Dead loop on virtual device ip6_vti0, fix it urgently!

=============================
WARNING: suspicious RCU usage
4.15.0-rc8+ #198 Not tainted
-----------------------------
./include/net/inet_sock.h:136 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
1 lock held by syz-executor7/18295:
 #0:  (sk_lock-AF_INET6){+.+.}, at: [<000000009d4bb12a>] lock_sock include/net/sock.h:1463 [inline]
 #0:  (sk_lock-AF_INET6){+.+.}, at: [<000000009d4bb12a>] do_ipv6_setsockopt.isra.9+0x23d/0x39a0 net/ipv6/ipv6_sockglue.c:167

stack backtrace:
CPU: 1 PID: 18295 Comm: syz-executor7 Not tainted 4.15.0-rc8+ #198
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:53
 lockdep_rcu_suspicious+0x123/0x170 kernel/locking/lockdep.c:4585
 ireq_opt_deref include/net/inet_sock.h:135 [inline]
 inet_csk_route_req+0x824/0xca0 net/ipv4/inet_connection_sock.c:544
 dccp_v4_send_response+0xa7/0x650 net/dccp/ipv4.c:485
 dccp_v4_conn_request+0x9ee/0x11b0 net/dccp/ipv4.c:633
 dccp_v6_conn_request+0xd30/0x1350 net/dccp/ipv6.c:317
 dccp_rcv_state_process+0x574/0x1620 net/dccp/input.c:612
 dccp_v4_do_rcv+0xf1/0x160 net/dccp/ipv4.c:682
 dccp_v6_do_rcv+0x823/0x9c0 net/dccp/ipv6.c:578
 sk_backlog_rcv include/net/sock.h:908 [inline]
 __release_sock+0x124/0x360 net/core/sock.c:2274
 release_sock+0xa4/0x2a0 net/core/sock.c:2789
 do_ipv6_setsockopt.isra.9+0x50a/0x39a0 net/ipv6/ipv6_sockglue.c:898
 ipv6_setsockopt+0xd7/0x150 net/ipv6/ipv6_sockglue.c:922
 dccp_setsockopt+0x85/0xd0 net/dccp/proto.c:576
 sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2978
 SYSC_setsockopt net/socket.c:1823 [inline]
 SyS_setsockopt+0x189/0x360 net/socket.c:1802
 entry_SYSCALL_64_fastpath+0x29/0xa0
RIP: 0033:0x452ee9
RSP: 002b:00007fee3ef55c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452ee9
RDX: 0000000000000020 RSI: 0000000000000029 RDI: 0000000000000013
RBP: 0000000000000059 R08: 0000000000000020 R09: 0000000000000000
R10: 00000000204ec000 R11: 0000000000000212 R12: 00000000006ef8f8
R13: 00000000ffffffff R14: 00007fee3ef566d4 R15: 0000000000000000

=============================
WARNING: suspicious RCU usage
4.15.0-rc8+ #198 Not tainted
-----------------------------
./include/net/inet_sock.h:136 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
1 lock held by syz-executor7/18295:
 #0:  (sk_lock-AF_INET6){+.+.}, at: [<000000009d4bb12a>] lock_sock include/net/sock.h:1463 [inline]
 #0:  (sk_lock-AF_INET6){+.+.}, at: [<000000009d4bb12a>] do_ipv6_setsockopt.isra.9+0x23d/0x39a0 net/ipv6/ipv6_sockglue.c:167

stack backtrace:
CPU: 1 PID: 18295 Comm: syz-executor7 Not tainted 4.15.0-rc8+ #198
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:53
 lockdep_rcu_suspicious+0x123/0x170 kernel/locking/lockdep.c:4585
 ireq_opt_deref include/net/inet_sock.h:135 [inline]
 dccp_v4_send_response+0x4b6/0x650 net/dccp/ipv4.c:496
 dccp_v4_conn_request+0x9ee/0x11b0 net/dccp/ipv4.c:633
 dccp_v6_conn_request+0xd30/0x1350 net/dccp/ipv6.c:317
 dccp_rcv_state_process+0x574/0x1620 net/dccp/input.c:612
 dccp_v4_do_rcv+0xf1/0x160 net/dccp/ipv4.c:682
 dccp_v6_do_rcv+0x823/0x9c0 net/dccp/ipv6.c:578
 sk_backlog_rcv include/net/sock.h:908 [inline]
 __release_sock+0x124/0x360 net/core/sock.c:2274
 release_sock+0xa4/0x2a0 net/core/sock.c:2789
 do_ipv6_setsockopt.isra.9+0x50a/0x39a0 net/ipv6/ipv6_sockglue.c:898
 ipv6_setsockopt+0xd7/0x150 net/ipv6/ipv6_sockglue.c:922
 dccp_setsockopt+0x85/0xd0 net/dccp/proto.c:576
 sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2978
 SYSC_setsockopt net/socket.c:1823 [inline]
 SyS_setsockopt+0x189/0x360 net/socket.c:1802
 entry_SYSCALL_64_fastpath+0x29/0xa0
RIP: 0033:0x452ee9
RSP: 002b:00007fee3ef55c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452ee9
RDX: 0000000000000020 RSI: 0000000000000029 RDI: 0000000000000013
RBP: 0000000000000059 R08: 0000000000000020 R09: 0000000000000000
R10: 00000000204ec000 R11: 0000000000000212 R12: 00000000006ef8f8
R13: 00000000ffffffff R14: 00007fee3ef566d4 R15: 0000000000000000
do_dccp_setsockopt: sockopt(PACKET_SIZE) is deprecated: fix your app
do_dccp_setsockopt: sockopt(PACKET_SIZE) is deprecated: fix your app
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=256 sclass=netlink_route_socket pig=18629 comm=syz-executor3
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=256 sclass=netlink_route_socket pig=18629 comm=syz-executor3
sctp: [Deprecated]: syz-executor6 (pid 18664) Use of int in max_burst socket option deprecated.
Use struct sctp_assoc_value instead
sctp: [Deprecated]: syz-executor6 (pid 18664) Use of int in max_burst socket option deprecated.
Use struct sctp_assoc_value instead
openvswitch: netlink: Flow get message rejected, Key attribute missing.
openvswitch: netlink: Flow get message rejected, Key attribute missing.
netlink: 8 bytes leftover after parsing attributes in process `syz-executor1'.
netlink: 8 bytes leftover after parsing attributes in process `syz-executor1'.
netlink: 'syz-executor5': attribute type 1 has an invalid length.
netlink: 'syz-executor5': attribute type 1 has an invalid length.
netlink: 'syz-executor0': attribute type 7 has an invalid length.
netlink: 'syz-executor0': attribute type 7 has an invalid length.
netlink: 'syz-executor5': attribute type 1 has an invalid length.
netlink: 'syz-executor5': attribute type 1 has an invalid length.
l2tp_ppp: sess 59/4096: set debug=f55d40e
l2tp_ppp: sess 59/4096: get L2TP stats
tc_ctl_action: received NO action attribs
TCP: request_sock_TCPv6: Possible SYN flooding on port 20026. Sending cookies.  Check SNMP counters.
tc_ctl_action: received NO action attribs
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=260 sclass=netlink_route_socket pig=19842 comm=syz-executor2
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=260 sclass=netlink_route_socket pig=19842 comm=syz-executor2
can: request_module (can-proto-5) failed.
can: request_module (can-proto-5) failed.
can: request_module (can-proto-0) failed.
can: request_module (can-proto-0) failed.
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=256 sclass=netlink_route_socket pig=20610 comm=syz-executor6
sctp: [Deprecated]: syz-executor5 (pid 20753) Use of struct sctp_assoc_value in delayed_ack socket option.
Use struct sctp_sack_info instead
sctp: [Deprecated]: syz-executor5 (pid 20753) Use of struct sctp_assoc_value in delayed_ack socket option.
Use struct sctp_sack_info instead
netlink: 2 bytes leftover after parsing attributes in process `syz-executor6'.
netlink: 2 bytes leftover after parsing attributes in process `syz-executor6'.
Trying to set illegal importance in message
Trying to set illegal importance in message
netlink: 8 bytes leftover after parsing attributes in process `syz-executor7'.
netlink: 8 bytes leftover after parsing attributes in process `syz-executor7'.