[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 62.881515][ T27] audit: type=1800 audit(1577278477.642:25): pid=9038 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 62.901228][ T27] audit: type=1800 audit(1577278477.642:26): pid=9038 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 62.933822][ T27] audit: type=1800 audit(1577278477.642:27): pid=9038 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.0.128' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program syzkaller login: [ 154.964359][ T9209] ------------[ cut here ]------------ [ 154.969858][ T9209] WARNING: CPU: 0 PID: 9209 at lib/percpu-refcount.c:111 percpu_ref_exit+0xab/0xd0 [ 154.979111][ T9209] Kernel panic - not syncing: panic_on_warn set ... [ 154.985712][ T9209] CPU: 0 PID: 9209 Comm: syz-executor433 Not tainted 5.5.0-rc2-next-20191220-syzkaller #0 [ 154.995579][ T9209] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 155.005611][ T9209] Call Trace: [ 155.008881][ T9209] dump_stack+0x197/0x210 [ 155.013202][ T9209] ? percpu_ref_exit+0x10/0xd0 [ 155.017961][ T9209] panic+0x2e3/0x75c [ 155.021839][ T9209] ? add_taint.cold+0x16/0x16 [ 155.026851][ T9209] ? printk+0xba/0xed [ 155.031981][ T9209] ? kmsg_dump_rewind_nolock+0xe4/0xe4 [ 155.037419][ T9209] ? __warn.cold+0x14/0x3e [ 155.041812][ T9209] ? __warn+0xd9/0x1cf [ 155.045865][ T9209] ? percpu_ref_exit+0xab/0xd0 [ 155.050608][ T9209] __warn.cold+0x2f/0x3e [ 155.054872][ T9209] ? report_bug.cold+0x63/0xb2 [ 155.059778][ T9209] ? percpu_ref_exit+0xab/0xd0 [ 155.064534][ T9209] report_bug+0x289/0x300 [ 155.068867][ T9209] do_error_trap+0x11b/0x200 [ 155.073441][ T9209] do_invalid_op+0x37/0x50 [ 155.078809][ T9209] ? percpu_ref_exit+0xab/0xd0 [ 155.083561][ T9209] invalid_op+0x23/0x30 [ 155.087695][ T9209] RIP: 0010:percpu_ref_exit+0xab/0xd0 [ 155.093046][ T9209] Code: 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 75 1d 48 c7 43 08 03 00 00 00 e8 01 41 e5 fd 5b 41 5c 41 5d 5d c3 e8 f5 40 e5 fd <0f> 0b eb bf 4c 89 ef e8 29 2c 23 fe eb d9 e8 82 2b 23 fe eb a7 4c [ 155.112632][ T9209] RSP: 0018:ffffc90002087bc0 EFLAGS: 00010293 [ 155.118675][ T9209] RAX: ffff88809fdd02c0 RBX: ffff8880a92f8210 RCX: ffffffff83901432 [ 155.126624][ T9209] RDX: 0000000000000000 RSI: ffffffff8390149b RDI: ffff8880a92f8228 [ 155.134573][ T9209] RBP: ffffc90002087bd8 R08: ffff88809fdd02c0 R09: 0000000000000000 [ 155.142522][ T9209] R10: 0000000000000000 R11: 0000000000000000 R12: 0000607f51434d60 [ 155.151339][ T9209] R13: ffff8880a92f8218 R14: ffff88809ae9b000 R15: ffff88809ae9b228 [ 155.159301][ T9209] ? percpu_ref_exit+0x42/0xd0 [ 155.164045][ T9209] ? percpu_ref_exit+0xab/0xd0 [ 155.168799][ T9209] io_sqe_files_unregister+0x7d/0x2f0 [ 155.174150][ T9209] ? __mmdrop+0x239/0x320 [ 155.178560][ T9209] io_ring_ctx_wait_and_kill+0x430/0x9a0 [ 155.184186][ T9209] ? __sanitizer_cov_trace_const_cmp2+0x11/0x20 [ 155.190418][ T9209] io_uring_release+0x42/0x50 [ 155.195102][ T9209] __fput+0x2ff/0x890 [ 155.199083][ T9209] ? io_ring_ctx_wait_and_kill+0x9a0/0x9a0 [ 155.204870][ T9209] ____fput+0x16/0x20 [ 155.208834][ T9209] task_work_run+0x145/0x1c0 [ 155.213407][ T9209] do_exit+0x909/0x2f20 [ 155.217555][ T9209] ? mm_update_next_owner+0x7c0/0x7c0 [ 155.222917][ T9209] ? down_read_non_owner+0x490/0x490 [ 155.228181][ T9209] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 155.234398][ T9209] ? handle_mm_fault+0x4ab/0xa50 [ 155.239314][ T9209] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 155.244756][ T9209] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 155.250194][ T9209] do_group_exit+0x135/0x360 [ 155.254767][ T9209] __x64_sys_exit_group+0x44/0x50 [ 155.259768][ T9209] do_syscall_64+0xfa/0x790 [ 155.264264][ T9209] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 155.270395][ T9209] RIP: 0033:0x43fee8 [ 155.274269][ T9209] Code: 00 00 be 3c 00 00 00 eb 19 66 0f 1f 84 00 00 00 00 00 48 89 d7 89 f0 0f 05 48 3d 00 f0 ff ff 77 21 f4 48 89 d7 44 89 c0 0f 05 <48> 3d 00 f0 ff ff 76 e0 f7 d8 64 41 89 01 eb d8 0f 1f 84 00 00 00 [ 155.294091][ T9209] RSP: 002b:00007fff966edb48 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 155.302482][ T9209] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043fee8 [ 155.310433][ T9209] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 155.318394][ T9209] RBP: 00000000004bf770 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 155.326350][ T9209] R10: 000000000000035b R11: 0000000000000246 R12: 0000000000000001 [ 155.334303][ T9209] R13: 00000000006d1180 R14: 0000000000000000 R15: 0000000000000000 [ 155.343750][ T9209] Kernel Offset: disabled [ 155.348133][ T9209] Rebooting in 86400 seconds..