------------[ cut here ]------------
WARNING: CPU: 0 PID: 17063 at include/net/sock.h:628 sk_nulls_del_node_init_rcu include/net/sock.h:628 [inline]()
WARNING: CPU: 0 PID: 17063 at include/net/sock.h:628 udp_lib_unhash+0x545/0x6a0 net/ipv4/udp.c:1406()
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 17063 Comm: syz-executor1 Not tainted 4.4.111-gc2f631b #27
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 0000000000000000 4d919bcfe886239b ffff8801d5f5f6c0 ffffffff81d0513d
 ffffffff83842f60 ffff8801d5f5f798 ffffffff83cf1840 0000000000000009
 0000000000000274 ffff8801d5f5f788 ffffffff81419a3a 0000000041b58ab3
Call Trace:
 [<ffffffff81d0513d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d0513d>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff81419a3a>] panic+0x1aa/0x388 kernel/panic.c:112
 [<ffffffff8112d7c5>] warn_slowpath_common+0x125/0x140 kernel/panic.c:455
 [<ffffffff8112da29>] warn_slowpath_null+0x29/0x30 kernel/panic.c:492
 [<ffffffff831a55a5>] sk_nulls_del_node_init_rcu include/net/sock.h:628 [inline]
 [<ffffffff831a55a5>] udp_lib_unhash+0x545/0x6a0 net/ipv4/udp.c:1406
 [<ffffffff82e00d3d>] sk_common_release+0xbd/0x300 net/core/sock.c:2690
 [<ffffffff8336ce65>] udp_lib_close+0x15/0x20 include/net/udp.h:190
 [<ffffffff831d0efa>] inet_release+0xfa/0x1d0 net/ipv4/af_inet.c:435
 [<ffffffff832f67b0>] inet6_release+0x50/0x70 net/ipv6/af_inet6.c:424
 [<ffffffff82de9b9d>] sock_release+0x8d/0x1e0 net/socket.c:586
 [<ffffffff82de9d06>] sock_close+0x16/0x20 net/socket.c:1037
 [<ffffffff81522a73>] __fput+0x233/0x6d0 fs/file_table.c:208
 [<ffffffff81522f95>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8118bae4>] task_work_run+0x104/0x180 kernel/task_work.c:115
 [<ffffffff81132eb1>] exit_task_work include/linux/task_work.h:21 [inline]
 [<ffffffff81132eb1>] do_exit+0x871/0x2a20 kernel/exit.c:755
 [<ffffffff81139328>] do_group_exit+0x108/0x320 kernel/exit.c:885
 [<ffffffff8115c825>] get_signal+0x565/0x1660 kernel/signal.c:2317
 [<ffffffff8100e7fb>] do_signal+0x8b/0x1d40 arch/x86/kernel/signal.c:712
 [<ffffffff81003602>] exit_to_usermode_loop+0x122/0x170 arch/x86/entry/common.c:247
 [<ffffffff81006545>] prepare_exit_to_usermode arch/x86/entry/common.c:282 [inline]
 [<ffffffff81006545>] syscall_return_slowpath+0x1b5/0x1f0 arch/x86/entry/common.c:347
 [<ffffffff83775a9d>] int_ret_from_sys_call+0x25/0xa3
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..