do_dccp_getsockopt: sockopt(PACKET_SIZE) is deprecated: fix your app
refcount_t: underflow; use-after-free.
------------[ cut here ]------------
WARNING: CPU: 1 PID: 17555 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: 17555 Comm: syz-executor2 Not tainted 4.14.0-rc1+ #44
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:ffff8801cf50ef88 EFLAGS: 00010282
RAX: 0000000000000026 RBX: 0000000000000001 RCX: 0000000000000000
RDX: 0000000000000026 RSI: ffffffff815899fe RDI: ffffed0039ea1de5
RBP: ffff8801cf50f018 R08: ffff8801cf50e6f8 R09: 0000000000000000
R10: ffff8801cac96240 R11: 0000000000000000 R12: 1ffff10039ea1df2
R13: 00000000ffffff01 R14: 0000000000000100 R15: ffff8801cb65aa24
 sctp_wfree+0x183/0x620 net/sctp/socket.c:7756
 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_datamsg_destroy net/sctp/chunk.c:129 [inline]
 sctp_datamsg_put+0x22d/0x560 net/sctp/chunk.c:146
 sctp_chunk_free+0x46/0x60 net/sctp/sm_make_chunk.c:1449
 __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_shutdown+0x1ff/0x2d0 net/sctp/socket.c:4470
 inet_shutdown+0x170/0x350 net/ipv4/af_inet.c:832
 SYSC_shutdown net/socket.c:1904 [inline]
 SyS_shutdown+0x137/0x290 net/socket.c:1895
 entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x451e59
RSP: 002b:00007f3e6e8d6c08 EFLAGS: 00000216 ORIG_RAX: 0000000000000030
RAX: ffffffffffffffda RBX: 0000000000718160 RCX: 0000000000451e59
RDX: 0000000000000000 RSI: 0000800000000002 RDI: 0000000000000006
RBP: 0000000000000082 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000216 R12: 00000000004b6eb1
R13: 00000000ffffffff R14: 0000000000000005 R15: 0000000020ce6ff0
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..