------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 1 PID: 8916 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: 8916 Comm: syz-executor619 Not tainted 5.5.0-rc1-next-20191213-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 41 31 23 fe e9 85 fe ff ff e8 a7 4e e5 fd 48 c7 c7 20 d8 6f 88 c6 05 75 96 ec 06 01 e8 73 de b5 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:ffffc900025875d0 EFLAGS: 00010282 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff815e8b66 RDI: fffff520004b0eac RBP: ffffc900025875e0 R08: ffff8880a959a2c0 R09: fffffbfff165a7ba R10: fffffbfff165a7b9 R11: ffffffff8b2d3dcf R12: 0000000000000003 R13: ffff88809339ba04 R14: 0000000000000900 R15: ffff8880a35ae7c0 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: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: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+0x3a4a/0x5160 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:592 sock_close+0x1e/0x30 net/socket.c:1270 __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+0x909/0x2f20 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] __x64_sys_exit_group+0x44/0x50 kernel/exit.c:904 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x43ef98 Code: Bad RIP value. RSP: 002b:00007ffd5b28f778 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ef98 RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 RBP: 00000000004be7a8 R08: 00000000000000e7 R09: ffffffffffffffd0 R10: 000000002059aff8 R11: 0000000000000246 R12: 0000000000000001 R13: 00000000006d01a0 R14: 0000000000000000 R15: 0000000000000000 Kernel Offset: disabled Rebooting in 86400 seconds..