===============================
[ INFO: suspicious RCU usage. ]
4.4.174+ #17 Not tainted
-------------------------------
net/ipv4/xfrm4_protocol.c:80 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 1, debug_locks = 0
no locks held by syz-executor.0/18240.

stack backtrace:
CPU: 1 PID: 18240 Comm: syz-executor.0 Not tainted 4.4.174+ #17
 0000000000000000 bb5aa652920d4b04 ffff8801d6def750 ffffffff81aad1a1
 ffffffff831af4e0 0000000000000000 0000000000000001 0000000000000050
 ffff8800b5f08000 ffff8801d6def780 ffffffff813ab7d6 ffff8800b5e178c0
Call Trace:
 [<ffffffff81aad1a1>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81aad1a1>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<ffffffff813ab7d6>] lockdep_rcu_suspicious.cold+0x10a/0x149 kernel/locking/lockdep.c:4305
 [<ffffffff8254222a>] xfrm4_rcv_encap+0x30a/0x370 net/ipv4/xfrm4_protocol.c:80
 [<ffffffff82540745>] xfrm4_udp_encap_rcv+0x3f5/0x620 net/ipv4/xfrm4_input.c:148
 [<ffffffff82482087>] udp_queue_rcv_skb+0xe57/0x14e0 net/ipv4/udp.c:1547
 [<ffffffff821e5e40>] sk_backlog_rcv include/net/sock.h:875 [inline]
 [<ffffffff821e5e40>] __release_sock net/core/sock.c:2024 [inline]
 [<ffffffff821e5e40>] release_sock+0x170/0x500 net/core/sock.c:2477
 [<ffffffff8247f646>] udp_sendmsg+0x1176/0x1c60 net/ipv4/udp.c:1107
 [<ffffffff824a8b42>] inet_sendmsg+0x202/0x4d0 net/ipv4/af_inet.c:755
 [<ffffffff821d838e>] sock_sendmsg_nosec net/socket.c:638 [inline]
 [<ffffffff821d838e>] sock_sendmsg+0xbe/0x110 net/socket.c:648
 [<ffffffff821d8615>] sock_write_iter+0x235/0x3d0 net/socket.c:847
 [<ffffffff81496ae8>] new_sync_write fs/read_write.c:480 [inline]
 [<ffffffff81496ae8>] __vfs_write+0x2e8/0x3d0 fs/read_write.c:493
 [<ffffffff81498612>] vfs_write+0x182/0x4e0 fs/read_write.c:540
 [<ffffffff8149ac4c>] SYSC_write fs/read_write.c:587 [inline]
 [<ffffffff8149ac4c>] SyS_write+0xdc/0x1c0 fs/read_write.c:579
 [<ffffffff8100603d>] do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline]
 [<ffffffff8100603d>] do_fast_syscall_32+0x32d/0xa90 arch/x86/entry/common.c:397
 [<ffffffff8271a350>] sysenter_flags_fixed+0xd/0x1a