------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 1 PID: 26487 at lib/refcount.c:28 refcount_warn_saturate+0x165/0x1b0 lib/refcount.c:28 Kernel panic - not syncing: panic_on_warn set ... CPU: 1 PID: 26487 Comm: syz-executor.1 Not tainted 5.6.0-rc1-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+0x1fb/0x318 lib/dump_stack.c:118 panic+0x264/0x7a9 kernel/panic.c:221 __warn+0x209/0x210 kernel/panic.c:582 report_bug+0x1b6/0x2f0 lib/bug.c:195 fixup_bug arch/x86/kernel/traps.c:174 [inline] do_error_trap+0xcf/0x1c0 arch/x86/kernel/traps.c:267 do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:286 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027 RIP: 0010:refcount_warn_saturate+0x165/0x1b0 lib/refcount.c:28 Code: c7 14 d4 f0 88 31 c0 e8 19 18 a8 fd 0f 0b eb 83 e8 70 58 d6 fd c6 05 6d 27 c5 05 01 48 c7 c7 40 d4 f0 88 31 c0 e8 fb 17 a8 fd <0f> 0b e9 62 ff ff ff e8 4f 58 d6 fd c6 05 4d 27 c5 05 01 48 c7 c7 RSP: 0018:ffffc90002f47768 EFLAGS: 00010246 RAX: 0e98f65c71c9cb00 RBX: 0000000000000003 RCX: ffff88804da6e400 RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000 RBP: ffffc90002f47778 R08: ffffffff815fef24 R09: ffffed1015d66618 R10: ffffed1015d66618 R11: 0000000000000000 R12: 0000000000008100 R13: 00000000ffffff01 R14: 0000000000000003 R15: ffff8880923e9a44 refcount_sub_and_test include/linux/refcount.h:261 [inline] sock_wfree+0x1d5/0x200 net/core/sock.c:1965 sctp_wfree+0x3c7/0x720 net/sctp/socket.c:9111 skb_release_head_state+0x100/0x210 net/core/skbuff.c:653 skb_release_all net/core/skbuff.c:664 [inline] __kfree_skb+0x25/0x1c0 net/core/skbuff.c:680 consume_skb+0x72/0x110 net/core/skbuff.c:839 sctp_chunk_destroy net/sctp/sm_make_chunk.c:1454 [inline] sctp_chunk_put+0x17b/0x200 net/sctp/sm_make_chunk.c:1481 sctp_chunk_free+0x59/0x60 net/sctp/sm_make_chunk.c:1468 __sctp_outq_teardown+0x849/0xa40 net/sctp/outqueue.c:257 sctp_outq_free+0x15/0x20 net/sctp/outqueue.c:277 sctp_association_free+0x271/0x880 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+0x3e1c/0x5840 net/sctp/sm_sideeffect.c:1156 sctp_primitive_ABORT+0x99/0xd0 net/sctp/primitive.c:104 sctp_close+0x253/0x7f0 net/sctp/socket.c:1512 inet_release+0x165/0x1c0 net/ipv4/af_inet.c:427 __sock_release net/socket.c:605 [inline] sock_close+0xe1/0x260 net/socket.c:1283 __fput+0x2e4/0x740 fs/file_table.c:280 ____fput+0x15/0x20 fs/file_table.c:313 task_work_run+0x176/0x1b0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop arch/x86/entry/common.c:164 [inline] prepare_exit_to_usermode+0x480/0x5b0 arch/x86/entry/common.c:195 syscall_return_slowpath+0x113/0x4a0 arch/x86/entry/common.c:278 do_syscall_64+0x11f/0x1c0 arch/x86/entry/common.c:304 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x416261 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:00007ffd01460200 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000009 RCX: 0000000000416261 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000008 RBP: 0000000000000001 R08: 00000000f350485e R09: ffffffffffffffff R10: 00007ffd014602e0 R11: 0000000000000293 R12: 000000000076bf20 R13: 000000000008bf74 R14: 0000000000771a58 R15: 000000000076bf2c Kernel Offset: disabled Rebooting in 86400 seconds..