[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 67.096157][ T28] audit: type=1800 audit(1577596909.785:25): pid=9328 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 67.117192][ T28] audit: type=1800 audit(1577596909.785:26): pid=9328 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 67.140230][ T28] audit: type=1800 audit(1577596909.785:27): pid=9328 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 '10.128.0.90' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program syzkaller login: [ 106.097310][T10258] ------------[ cut here ]------------ [ 106.102822][T10258] WARNING: CPU: 1 PID: 10258 at lib/percpu-refcount.c:111 percpu_ref_exit+0xab/0xd0 [ 106.112265][T10258] Kernel panic - not syncing: panic_on_warn set ... [ 106.119084][T10258] CPU: 1 PID: 10258 Comm: syz-executor336 Not tainted 5.5.0-rc2-next-20191220-syzkaller #0 [ 106.129043][T10258] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 106.139080][T10258] Call Trace: [ 106.142371][T10258] dump_stack+0x197/0x210 [ 106.146701][T10258] ? percpu_ref_exit+0x10/0xd0 [ 106.151455][T10258] panic+0x2e3/0x75c [ 106.155348][T10258] ? add_taint.cold+0x16/0x16 [ 106.160016][T10258] ? printk+0xba/0xed [ 106.163987][T10258] ? kmsg_dump_rewind_nolock+0xe4/0xe4 [ 106.169426][T10258] ? __warn.cold+0x14/0x3e [ 106.173821][T10258] ? __warn+0xd9/0x1cf [ 106.177886][T10258] ? percpu_ref_exit+0xab/0xd0 [ 106.182630][T10258] __warn.cold+0x2f/0x3e [ 106.186856][T10258] ? report_bug.cold+0x63/0xb2 [ 106.191617][T10258] ? percpu_ref_exit+0xab/0xd0 [ 106.196367][T10258] report_bug+0x289/0x300 [ 106.200680][T10258] do_error_trap+0x11b/0x200 [ 106.205251][T10258] do_invalid_op+0x37/0x50 [ 106.209649][T10258] ? percpu_ref_exit+0xab/0xd0 [ 106.214411][T10258] invalid_op+0x23/0x30 [ 106.218635][T10258] RIP: 0010:percpu_ref_exit+0xab/0xd0 [ 106.223997][T10258] 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 [ 106.243587][T10258] RSP: 0018:ffffc90004237968 EFLAGS: 00010293 [ 106.249640][T10258] RAX: ffff888096c8e040 RBX: ffff888098462210 RCX: ffffffff83901432 [ 106.257651][T10258] RDX: 0000000000000000 RSI: ffffffff8390149b RDI: ffff888098462228 [ 106.265619][T10258] RBP: ffffc90004237980 R08: ffff888096c8e040 R09: 0000000000000000 [ 106.273586][T10258] R10: 0000000000000000 R11: 0000000000000000 R12: 0000607f51435a08 [ 106.281585][T10258] R13: ffff888098462218 R14: ffff888097872000 R15: ffff888097872228 [ 106.289557][T10258] ? percpu_ref_exit+0x42/0xd0 [ 106.294317][T10258] ? percpu_ref_exit+0xab/0xd0 [ 106.299131][T10258] ? percpu_ref_exit+0xab/0xd0 [ 106.303879][T10258] io_sqe_files_unregister+0x7d/0x2f0 [ 106.309232][T10258] ? __mmdrop+0x239/0x320 [ 106.313545][T10258] io_ring_ctx_wait_and_kill+0x430/0x9a0 [ 106.319159][T10258] ? __sanitizer_cov_trace_const_cmp2+0x11/0x20 [ 106.325556][T10258] io_uring_release+0x42/0x50 [ 106.330221][T10258] __fput+0x2ff/0x890 [ 106.334190][T10258] ? io_ring_ctx_wait_and_kill+0x9a0/0x9a0 [ 106.340017][T10258] ____fput+0x16/0x20 [ 106.344030][T10258] task_work_run+0x145/0x1c0 [ 106.348622][T10258] do_exit+0x909/0x2f20 [ 106.352781][T10258] ? get_signal+0x2c1/0x24f0 [ 106.357403][T10258] ? mm_update_next_owner+0x7c0/0x7c0 [ 106.362819][T10258] ? lock_downgrade+0x920/0x920 [ 106.367680][T10258] ? _raw_spin_unlock_irq+0x23/0x80 [ 106.372893][T10258] ? get_signal+0x392/0x24f0 [ 106.377466][T10258] ? _raw_spin_unlock_irq+0x23/0x80 [ 106.382650][T10258] do_group_exit+0x135/0x360 [ 106.387223][T10258] get_signal+0x47c/0x24f0 [ 106.391625][T10258] ? __x64_sys_io_uring_register+0x1b0/0x570 [ 106.397587][T10258] ? __io_uring_register+0x118/0x2790 [ 106.402956][T10258] do_signal+0x87/0x1700 [ 106.407200][T10258] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 106.413421][T10258] ? debug_smp_processor_id+0x33/0x18a [ 106.418880][T10258] ? rcu_lockdep_current_cpu_online+0xe3/0x130 [ 106.425033][T10258] ? setup_sigcontext+0x7d0/0x7d0 [ 106.430059][T10258] ? rcu_read_lock_sched_held+0x9c/0xd0 [ 106.435611][T10258] ? exit_to_usermode_loop+0x43/0x380 [ 106.440975][T10258] ? do_syscall_64+0x676/0x790 [ 106.445726][T10258] ? exit_to_usermode_loop+0x43/0x380 [ 106.451086][T10258] ? lockdep_hardirqs_on+0x421/0x5e0 [ 106.456469][T10258] ? trace_hardirqs_on+0x67/0x240 [ 106.461479][T10258] exit_to_usermode_loop+0x286/0x380 [ 106.466746][T10258] do_syscall_64+0x676/0x790 [ 106.471317][T10258] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 106.477185][T10258] RIP: 0033:0x446899 [ 106.481233][T10258] Code: e8 0c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 5b 07 fc ff c3 66 2e 0f 1f 84 00 00 00 00 [ 106.500824][T10258] RSP: 002b:00007ff912baddb8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca [ 106.509265][T10258] RAX: fffffffffffffe00 RBX: 00000000006dbc28 RCX: 0000000000446899 [ 106.517221][T10258] RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00000000006dbc28 [ 106.525183][T10258] RBP: 00000000006dbc20 R08: 0000000000000000 R09: 0000000000000000 [ 106.533220][T10258] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc2c [ 106.541193][T10258] R13: 00007ffe93fdb26f R14: 00007ff912bae9c0 R15: 000000000000002d [ 106.550489][T10258] Kernel Offset: disabled [ 106.554874][T10258] Rebooting in 86400 seconds..