------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 1 PID: 9002 at lib/refcount.c:28 refcount_warn_saturate+0x1dc/0x1f0 lib/refcount.c:28
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 9002 Comm: syz-executor847 Not tainted 5.4.0-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+0x197/0x210 lib/dump_stack.c:118
 panic+0x2e3/0x75c kernel/panic.c:221
 __warn.cold+0x2f/0x3e kernel/panic.c:582
 report_bug+0x289/0x300 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+0x11b/0x200 arch/x86/kernel/traps.c:267
 do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:286
 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
RIP: 0010:refcount_warn_saturate+0x1dc/0x1f0 lib/refcount.c:28
Code: e9 d8 fe ff ff 48 89 df e8 31 65 25 fe e9 85 fe ff ff e8 07 37 e8 fd 48 c7 c7 60 53 4f 88 c6 05 7d b6 a5 06 01 e8 73 eb b8 fd <0f> 0b e9 ac fe ff ff 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 55 48
RSP: 0018:ffff888090cef5c0 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff815e4316 RDI: ffffed101219deaa
RBP: ffff888090cef5d0 R08: ffff888095dee1c0 R09: fffffbfff15d29b2
R10: fffffbfff15d29b1 R11: ffffffff8ae94d8f R12: 0000000000000003
R13: ffff8880a1645a04 R14: 0000000000000900 R15: ffff8880a93337c0
 refcount_sub_and_test include/linux/refcount.h:261 [inline]
 sock_wfree+0x1f8/0x260 net/core/sock.c:1965
 sctp_wfree+0x389/0x990 net/sctp/socket.c:9113
 skb_release_head_state+0xeb/0x260 net/core/skbuff.c:652
 skb_release_all+0x16/0x60 net/core/skbuff.c:663
 __kfree_skb net/core/skbuff.c:679 [inline]
 consume_skb net/core/skbuff.c:838 [inline]
 consume_skb+0xfb/0x410 net/core/skbuff.c:832
 sctp_chunk_destroy net/sctp/sm_make_chunk.c:1454 [inline]
 sctp_chunk_put+0x1d4/0x2f0 net/sctp/sm_make_chunk.c:1481
 sctp_chunk_free+0x56/0x70 net/sctp/sm_make_chunk.c:1468
 __sctp_outq_teardown+0x1d0/0xc60 net/sctp/outqueue.c:219
 sctp_outq_free+0x16/0x20 net/sctp/outqueue.c:276
 sctp_association_free+0x208/0x7e0 net/sctp/associola.c:339
 sctp_cmd_delete_tcb net/sctp/sm_sideeffect.c:934 [inline]
 sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1322 [inline]
 sctp_side_effects net/sctp/sm_sideeffect.c:1189 [inline]
 sctp_do_sm+0x3a6a/0x5190 net/sctp/sm_sideeffect.c:1160
 sctp_primitive_ABORT+0xa0/0xd0 net/sctp/primitive.c:104
 sctp_close+0x259/0x960 net/sctp/socket.c:1513
 inet_release+0xed/0x200 net/ipv4/af_inet.c:427
 __sock_release+0xce/0x280 net/socket.c:591
 sock_close+0x1e/0x30 net/socket.c:1269
 __fput+0x2ff/0x890 fs/file_table.c:280
 ____fput+0x16/0x20 fs/file_table.c:313
 task_work_run+0x145/0x1c0 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x8e7/0x2ef0 kernel/exit.c:797
 do_group_exit+0x135/0x360 kernel/exit.c:895
 __do_sys_exit_group kernel/exit.c:906 [inline]
 __se_sys_exit_group kernel/exit.c:904 [inline]
 __ia32_sys_exit_group+0x44/0x50 kernel/exit.c:904
 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
 do_fast_syscall_32+0x27b/0xe16 arch/x86/entry/common.c:408
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7f23a39
Code: Bad RIP value.
RSP: 002b:00000000ffffaecc EFLAGS: 00000296 ORIG_RAX: 00000000000000fc
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000080eb2d8
RDX: 0000000000000000 RSI: 00000000080d5f78 RDI: 00000000080eb2e0
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..