------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 1 PID: 14188 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: 14188 Comm: syz-executor.2 Not tainted 5.6.0-rc3-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 71 67 11 fe e9 85 fe ff ff e8 37 c1 d2 fd 48 c7 c7 40 9d 91 88 c6 05 5f 38 fe 06 01 e8 c3 12 a3 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:ffffc90006f87690 EFLAGS: 00010282 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff815ebe46 RDI: fffff52000df0ec4 RBP: ffffc90006f876a0 R08: ffff88805719e640 R09: ffffed1015d245c9 R10: ffffed1015d245c8 R11: ffff8880ae922e43 R12: 0000000000000003 R13: ffff8880a76ada44 R14: 0000000000000500 R15: ffff8880915d1d40 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:9111 skb_release_head_state+0xeb/0x260 net/core/skbuff.c:651 skb_release_all+0x16/0x60 net/core/skbuff.c:662 __kfree_skb net/core/skbuff.c:678 [inline] consume_skb net/core/skbuff.c:837 [inline] consume_skb+0xfb/0x410 net/core/skbuff.c:831 sctp_chunk_destroy net/sctp/sm_make_chunk.c:1454 [inline] sctp_chunk_put+0x1d4/0x2f0 net/sctp/sm_make_chunk.c:1481 sctp_datamsg_destroy net/sctp/chunk.c:111 [inline] sctp_datamsg_put+0x134/0x5e0 net/sctp/chunk.c:128 sctp_chunk_free+0x49/0x70 net/sctp/sm_make_chunk.c:1466 __sctp_outq_teardown+0x71f/0xc60 net/sctp/outqueue.c:257 sctp_outq_free+0x16/0x20 net/sctp/outqueue.c:277 sctp_association_free+0x208/0x7e0 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+0x3b9a/0x5330 net/sctp/sm_sideeffect.c:1156 sctp_primitive_ABORT+0xa0/0xd0 net/sctp/primitive.c:104 sctp_close+0x259/0x960 net/sctp/socket.c:1512 inet_release+0xed/0x200 net/ipv4/af_inet.c:427 __sock_release+0xce/0x280 net/socket.c:605 sock_close+0x1e/0x30 net/socket.c:1283 __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 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop+0x316/0x380 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_32_irqs_on arch/x86/entry/common.c:352 [inline] do_fast_syscall_32+0xbbd/0xe16 arch/x86/entry/common.c:408 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 RIP: 0023:0xf7fc2e39 Code: 1d 00 00 00 89 d3 5b 5e 5d c3 8b 04 24 c3 8b 1c 24 c3 8b 3c 24 c3 90 90 90 90 90 90 90 90 90 90 90 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90 RSP: 002b:000000000868fbec EFLAGS: 00000212 ORIG_RAX: 0000000000000006 RAX: 0000000000000000 RBX: 0000000000000007 RCX: 0000000000000000 RDX: 0000000000000008 RSI: 000000000817b640 RDI: 0000000000053114 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Kernel Offset: disabled Rebooting in 86400 seconds..