------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 0 PID: 8526 at lib/refcount.c:190 refcount_sub_and_test_checked lib/refcount.c:190 [inline] WARNING: CPU: 0 PID: 8526 at lib/refcount.c:190 refcount_sub_and_test_checked+0x1d0/0x200 lib/refcount.c:180 Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 8526 Comm: syz-executor152 Not tainted 5.4.0-rc8-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/0x35 kernel/panic.c:582 report_bug+0x289/0x300 lib/bug.c:195 fixup_bug arch/x86/kernel/traps.c:179 [inline] fixup_bug arch/x86/kernel/traps.c:174 [inline] do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:272 do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:291 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1028 RIP: 0010:refcount_sub_and_test_checked lib/refcount.c:190 [inline] RIP: 0010:refcount_sub_and_test_checked+0x1d0/0x200 lib/refcount.c:180 Code: 1d 30 da 7d 06 31 ff 89 de e8 3c 9b 2e fe 84 db 75 94 e8 f3 99 2e fe 48 c7 c7 40 b9 e6 87 c6 05 10 da 7d 06 01 e8 08 cd ff fd <0f> 0b e9 75 ff ff ff e8 d4 99 2e fe e9 6e ff ff ff 48 89 df e8 17 RSP: 0018:ffff8880968ff530 EFLAGS: 00010282 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff815cf766 RDI: ffffed1012d1fe98 RBP: ffff8880968ff5c8 R08: ffff8880994785c0 R09: ffffed1015d04101 R10: ffffed1015d04100 R11: ffff8880ae820807 R12: 00000000ffffff01 R13: 0000000000000001 R14: ffff8880968ff5a0 R15: 0000000000008001 sock_wfree+0xc3/0x190 net/core/sock.c:1967 sctp_wfree+0x336/0x920 net/sctp/socket.c:8998 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/0x3b0 net/core/skbuff.c:832 sctp_chunk_destroy net/sctp/sm_make_chunk.c:1454 [inline] sctp_chunk_put+0x192/0x280 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+0x208/0x79a net/sctp/associola.c:336 sctp_cmd_delete_tcb net/sctp/sm_sideeffect.c:929 [inline] sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1317 [inline] sctp_side_effects net/sctp/sm_sideeffect.c:1184 [inline] sctp_do_sm+0x3a75/0x5170 net/sctp/sm_sideeffect.c:1155 sctp_primitive_ABORT+0xa0/0xd0 net/sctp/primitive.c:104 sctp_close+0x259/0x880 net/sctp/socket.c:1513 inet_release+0xed/0x200 net/ipv4/af_inet.c:427 __sock_release+0xce/0x280 net/socket.c:590 sock_close+0x1e/0x30 net/socket.c:1268 __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+0x904/0x2e60 kernel/exit.c:817 do_group_exit+0x135/0x360 kernel/exit.c:921 __do_sys_exit_group kernel/exit.c:932 [inline] __se_sys_exit_group kernel/exit.c:930 [inline] __ia32_sys_exit_group+0x44/0x50 kernel/exit.c:930 do_syscall_32_irqs_on arch/x86/entry/common.c:333 [inline] do_fast_syscall_32+0x27b/0xdb3 arch/x86/entry/common.c:404 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 RIP: 0023:0xf7f57a39 Code: Bad RIP value. RSP: 002b:00000000fff4690c EFLAGS: 00000296 ORIG_RAX: 00000000000000fc RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000080eb2d8 RDX: 0000000000000000 RSI: 00000000080d61d8 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..