------------[ cut here ]------------
WARNING: CPU: 1 PID: 2924 at lib/refcount.c:186 refcount_sub_and_test+0x167/0x1b0 lib/refcount.c:186
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 2924 Comm: syzkaller290734 Not tainted 4.13.0-rc4+ #31
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:16 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:52
 panic+0x1e4/0x417 kernel/panic.c:180
 __warn+0x1c4/0x1d9 kernel/panic.c:541
 report_bug+0x211/0x2d0 lib/bug.c:183
 fixup_bug+0x40/0x90 arch/x86/kernel/traps.c:190
 do_trap_no_signal arch/x86/kernel/traps.c:224 [inline]
 do_trap+0x260/0x390 arch/x86/kernel/traps.c:273
 do_error_trap+0x120/0x390 arch/x86/kernel/traps.c:310
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:323
 invalid_op+0x1e/0x30 arch/x86/entry/entry_64.S:846
RIP: 0010:refcount_sub_and_test+0x167/0x1b0 lib/refcount.c:186
RSP: 0018:ffff8801d35c6ce8 EFLAGS: 00010286
RAX: 0000000000000026 RBX: 0000000000000001 RCX: 0000000000000000
RDX: 0000000000000026 RSI: 1ffff1003a6b8d5d RDI: ffffed003a6b8d91
RBP: ffff8801d35c6d78 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff1003a6b8d9e
R13: 00000000ffffff01 R14: 0000000000000100 R15: ffff8801d006927c
 sctp_wfree+0x183/0x620 net/sctp/socket.c:7745
 skb_release_head_state+0x124/0x200 net/core/skbuff.c:652
 skb_release_all+0x15/0x60 net/core/skbuff.c:665
 __kfree_skb net/core/skbuff.c:681 [inline]
 consume_skb+0x153/0x490 net/core/skbuff.c:748
 sctp_chunk_destroy net/sctp/sm_make_chunk.c:1441 [inline]
 sctp_chunk_put+0x29c/0x420 net/sctp/sm_make_chunk.c:1468
 sctp_chunk_free+0x53/0x60 net/sctp/sm_make_chunk.c:1455
 __sctp_outq_teardown+0xc7d/0x15a0 net/sctp/outqueue.c:264
 sctp_outq_free+0x15/0x20 net/sctp/outqueue.c:284
 sctp_association_free+0x2d0/0x930 net/sctp/associola.c:358
 sctp_cmd_delete_tcb net/sctp/sm_sideeffect.c:917 [inline]
 sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1333 [inline]
 sctp_side_effects net/sctp/sm_sideeffect.c:1198 [inline]
 sctp_do_sm+0x28e7/0x6d90 net/sctp/sm_sideeffect.c:1170
 sctp_primitive_SHUTDOWN+0xa0/0xd0 net/sctp/primitive.c:104
 sctp_close+0x3c6/0x980 net/sctp/socket.c:1531
 inet_release+0xed/0x1c0 net/ipv4/af_inet.c:425
 sock_release+0x8d/0x1e0 net/socket.c:597
 sock_close+0x16/0x20 net/socket.c:1112
 __fput+0x327/0x7e0 fs/file_table.c:210
 ____fput+0x15/0x20 fs/file_table.c:246
 task_work_run+0x18a/0x260 kernel/task_work.c:116
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x26d/0x2d0 arch/x86/entry/common.c:161
 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
 syscall_return_slowpath+0x3a7/0x450 arch/x86/entry/common.c:263
 entry_SYSCALL_64_fastpath+0xbc/0xbe
RIP: 0033:0x445d99
RSP: 002b:00007feb5f0dfdc8 EFLAGS: 00000202 ORIG_RAX: 000000000000002b
RAX: ffffffffffffff99 RBX: 0000000000000000 RCX: 0000000000445d99
RDX: 0000000020ffd000 RSI: 0000000020ffc000 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007feb5f0e0700 R09: 00007feb5f0e0700
R10: 00007feb5f0e0700 R11: 0000000000000202 R12: 0000000000000000
R13: 00007fff8d1a479f R14: 00007feb5f0e09c0 R15: 0000000000000000
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..