------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 0 PID: 17067 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 lib/refcount.c:28
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 17067 Comm: syz-executor.0 Not tainted 5.6.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x188/0x20d lib/dump_stack.c:118
 panic+0x2e3/0x75c kernel/panic.c:221
 __warn.cold+0x2f/0x35 kernel/panic.c:582
 report_bug+0x27b/0x2f0 lib/bug.c:195
 fixup_bug arch/x86/kernel/traps.c:174 [inline]
 fixup_bug arch/x86/kernel/traps.c:169 [inline]
 do_error_trap+0x12b/0x220 arch/x86/kernel/traps.c:267
 do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:286
 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 lib/refcount.c:28
Code: e9 db fe ff ff 48 89 df e8 6c 64 1f fe e9 8a fe ff ff e8 12 9b e2 fd 48 c7 c7 00 a9 51 88 c6 05 a6 a1 d1 06 01 e8 f7 ab b4 fd <0f> 0b e9 af fe ff ff 0f 1f 84 00 00 00 00 00 41 56 41 55 41 54 55
RSP: 0018:ffffc9001744f7e8 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff815c06c1 RDI: fffff52002e89eef
RBP: 0000000000000003 R08: ffff888030bea540 R09: ffffed1015cc6659
R10: ffffed1015cc6658 R11: ffff8880ae6332c7 R12: 0000000000008100
R13: ffff888089b6da04 R14: ffff8880a88eed00 R15: ffff8880a88eed40
 refcount_sub_and_test include/linux/refcount.h:261 [inline]
 sock_wfree+0x1e3/0x240 net/core/sock.c:1968
 sctp_wfree+0x372/0x960 net/sctp/socket.c:9111
 skb_release_head_state+0xe2/0x250 net/core/skbuff.c:651
 skb_release_all+0x11/0x60 net/core/skbuff.c:662
 __kfree_skb net/core/skbuff.c:678 [inline]
 consume_skb net/core/skbuff.c:837 [inline]
 consume_skb+0xf3/0x400 net/core/skbuff.c:831
 sctp_chunk_destroy net/sctp/sm_make_chunk.c:1454 [inline]
 sctp_chunk_put+0x1c0/0x2d0 net/sctp/sm_make_chunk.c:1481
 __sctp_outq_teardown+0x715/0xc60 net/sctp/outqueue.c:257
 sctp_association_free+0x212/0x7e0 net/sctp/associola.c:339
 sctp_cmd_delete_tcb net/sctp/sm_sideeffect.c:930 [inline]
 sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1318 [inline]
 sctp_side_effects net/sctp/sm_sideeffect.c:1185 [inline]
 sctp_do_sm+0x3911/0x4ed0 net/sctp/sm_sideeffect.c:1156
 sctp_primitive_ABORT+0x9b/0xc0 net/sctp/primitive.c:104
 sctp_close+0x22e/0x8a0 net/sctp/socket.c:1512
 inet_release+0xe4/0x1f0 net/ipv4/af_inet.c:427
 __sock_release+0xcd/0x280 net/socket.c:605
 sock_close+0x18/0x20 net/socket.c:1283
 __fput+0x2da/0x850 fs/file_table.c:280
 task_work_run+0x13f/0x1b0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x2fa/0x360 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_64+0x6b1/0x7d0 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4163e1
Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 1b 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007ffd24223800 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000007 RCX: 00000000004163e1
RDX: 0000000000000000 RSI: 0000000000001dcd RDI: 0000000000000006
RBP: 0000000000000001 R08: 00000000bce29dcd R09: 00000000bce29dd1
R10: 00007ffd242238e0 R11: 0000000000000293 R12: 000000000076bf00
R13: 00000000007710d8 R14: 0000000000114322 R15: 000000000076bf0c
Kernel Offset: disabled
Rebooting in 86400 seconds..