------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 0 PID: 11499 at lib/refcount.c:28 refcount_warn_saturate+0x1dc/0x1f0 lib/refcount.c:28 Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 11499 Comm: syz-executor.5 Not tainted 5.6.0-rc2-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 c1 a4 11 fe e9 85 fe ff ff e8 d7 ff d2 fd 48 c7 c7 c0 98 91 88 c6 05 b6 73 fe 06 01 e8 83 47 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:ffffc90006d9f720 EFLAGS: 00010286 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff815eae46 RDI: fffff52000db3ed6 RBP: ffffc90006d9f730 R08: ffff88805551c280 R09: ffffed1015d06659 R10: ffffed1015d06658 R11: ffff8880ae8332c7 R12: 0000000000000003 R13: ffff8880a605f244 R14: 0000000000008100 R15: ffff8880a47fd540 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:653 skb_release_all+0x16/0x60 net/core/skbuff.c:664 __kfree_skb net/core/skbuff.c:680 [inline] consume_skb net/core/skbuff.c:839 [inline] consume_skb+0xfb/0x410 net/core/skbuff.c:833 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+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_64+0x676/0x790 arch/x86/entry/common.c:304 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x416251 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:00007ffc3751f010 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000007 RCX: 0000000000416251 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000006 RBP: 0000000000000001 R08: 000000001a9802da R09: 000000001a9802de R10: 00007ffc3751f0f0 R11: 0000000000000293 R12: 000000000076bf20 R13: 0000000000771560 R14: 000000000005744a R15: 000000000076bf2c Kernel Offset: disabled Rebooting in 86400 seconds..