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WARNING: CPU: 0 PID: 2990 at lib/refcount.c:186 refcount_sub_and_test+0x167/0x1b0 lib/refcount.c:186
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 2990 Comm: syzkaller520154 Not tainted 4.14.0-rc6+ #56
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:181
 __warn+0x1c4/0x1d9 kernel/panic.c:542
 report_bug+0x211/0x2d0 lib/bug.c:183
 fixup_bug+0x40/0x90 arch/x86/kernel/traps.c:178
 do_trap_no_signal arch/x86/kernel/traps.c:212 [inline]
 do_trap+0x260/0x390 arch/x86/kernel/traps.c:261
 do_error_trap+0x120/0x390 arch/x86/kernel/traps.c:298
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:311
 invalid_op+0x18/0x20 arch/x86/entry/entry_64.S:905
RIP: 0010:refcount_sub_and_test+0x167/0x1b0 lib/refcount.c:186
RSP: 0018:ffff8801d1ff6858 EFLAGS: 00010286
RAX: 0000000000000026 RBX: 0000000000000001 RCX: 0000000000000000
RDX: 0000000000000026 RSI: 1ffff1003a3feccb RDI: ffffed003a3fecff
RBP: ffff8801d1ff68e8 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff1003a3fed0c
R13: 00000000ffffff01 R14: 0000000000000100 R15: ffff8801d1fd52bc
 sctp_wfree+0x183/0x620 net/sctp/socket.c:7760
 skb_release_head_state+0x124/0x200 net/core/skbuff.c:616
 skb_release_all+0x15/0x60 net/core/skbuff.c:629
 __kfree_skb net/core/skbuff.c:645 [inline]
 consume_skb+0x153/0x490 net/core/skbuff.c:705
 sctp_chunk_destroy net/sctp/sm_make_chunk.c:1437 [inline]
 sctp_chunk_put+0x29c/0x420 net/sctp/sm_make_chunk.c:1464
 sctp_chunk_free+0x53/0x60 net/sctp/sm_make_chunk.c:1451
 __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:357
 sctp_cmd_delete_tcb net/sctp/sm_sideeffect.c:919 [inline]
 sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1333 [inline]
 sctp_side_effects net/sctp/sm_sideeffect.c:1200 [inline]
 sctp_do_sm+0x28e7/0x6dd0 net/sctp/sm_sideeffect.c:1171
 sctp_primitive_SHUTDOWN+0xa0/0xd0 net/sctp/primitive.c:104
 sctp_close+0x3c6/0x980 net/sctp/socket.c:1532
 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:1126
 __fput+0x327/0x7e0 fs/file_table.c:210
 ____fput+0x15/0x20 fs/file_table.c:244
 task_work_run+0x199/0x270 kernel/task_work.c:112
 get_signal+0x1343/0x16d0 kernel/signal.c:2164
 do_signal+0x94/0x1ee0 arch/x86/kernel/signal.c:808
 exit_to_usermode_loop+0x214/0x310 arch/x86/entry/common.c:158
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:266 [inline]
 do_syscall_32_irqs_on arch/x86/entry/common.c:335 [inline]
 do_fast_syscall_32+0x83e/0xf05 arch/x86/entry/common.c:391
 entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:124
RIP: 0023:0xf7fdcc79
RSP: 002b:00000000f67d51ec EFLAGS: 00000296 ORIG_RAX: 000000000000016c
RAX: fffffffffffffff2 RBX: 0000000000000003 RCX: 0000000020b53ff0
RDX: 0000000020137ffc RSI: 0000000000080000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..