[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 89.891826][ T27] audit: type=1800 audit(1578585099.045:25): pid=9425 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 89.911508][ T27] audit: type=1800 audit(1578585099.045:26): pid=9425 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 89.960300][ T27] audit: type=1800 audit(1578585099.045:27): pid=9425 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 '10.128.0.146' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 100.703299][ T9576] ------------[ cut here ]------------ [ 100.708932][ T9576] refcount_t: underflow; use-after-free. [ 100.715202][ T9576] WARNING: CPU: 0 PID: 9576 at lib/refcount.c:28 refcount_warn_saturate+0x1dc/0x1f0 [ 100.724580][ T9576] Kernel panic - not syncing: panic_on_warn set ... [ 100.731157][ T9576] CPU: 0 PID: 9576 Comm: syz-executor192 Not tainted 5.5.0-rc5-next-20200109-syzkaller #0 [ 100.741020][ T9576] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 100.751053][ T9576] Call Trace: [ 100.754330][ T9576] dump_stack+0x197/0x210 [ 100.758641][ T9576] ? refcount_warn_saturate+0x1a0/0x1f0 [ 100.764163][ T9576] panic+0x2e3/0x75c [ 100.768065][ T9576] ? add_taint.cold+0x16/0x16 [ 100.772722][ T9576] ? __kasan_check_write+0x14/0x20 [ 100.777811][ T9576] ? __warn.cold+0x14/0x3e [ 100.782206][ T9576] ? __warn+0xd9/0x1cf [ 100.786254][ T9576] ? refcount_warn_saturate+0x1dc/0x1f0 [ 100.791792][ T9576] __warn.cold+0x2f/0x3e [ 100.796021][ T9576] ? refcount_warn_saturate+0x1dc/0x1f0 [ 100.801565][ T9576] report_bug+0x289/0x300 [ 100.805929][ T9576] do_error_trap+0x11b/0x200 [ 100.810500][ T9576] do_invalid_op+0x37/0x50 [ 100.814907][ T9576] ? refcount_warn_saturate+0x1dc/0x1f0 [ 100.820431][ T9576] invalid_op+0x23/0x30 [ 100.824564][ T9576] RIP: 0010:refcount_warn_saturate+0x1dc/0x1f0 [ 100.830746][ T9576] Code: e9 d8 fe ff ff 48 89 df e8 e1 a6 13 fe e9 85 fe ff ff e8 57 bd d5 fd 48 c7 c7 00 43 91 88 c6 05 3f dd ff 06 01 e8 d3 43 a6 fd <0f> 0b e9 ac fe ff ff 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 55 48 [ 100.850332][ T9576] RSP: 0018:ffffc900065dfbf0 EFLAGS: 00010282 [ 100.856376][ T9576] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 100.864330][ T9576] RDX: 0000000000000000 RSI: ffffffff815e68c6 RDI: fffff52000cbbf70 [ 100.872290][ T9576] RBP: ffffc900065dfc00 R08: ffff8880a2bd6600 R09: 0000000000000000 [ 100.880242][ T9576] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000003 [ 100.888198][ T9576] R13: ffff88809ffd19d8 R14: ffff88809ffd1980 R15: ffffffff8a244fe0 [ 100.896161][ T9576] ? vprintk_func+0x86/0x189 [ 100.900775][ T9576] put_watch+0xa2/0xb0 [ 100.904823][ T9576] watch_queue_release+0x34b/0xc40 [ 100.909920][ T9576] __fput+0x2ff/0x890 [ 100.913894][ T9576] ? __post_watch_notification+0x840/0x840 [ 100.919684][ T9576] ____fput+0x16/0x20 [ 100.923647][ T9576] task_work_run+0x145/0x1c0 [ 100.928233][ T9576] do_exit+0xbcb/0x2f70 [ 100.932380][ T9576] ? find_held_lock+0x35/0x130 [ 100.937126][ T9576] ? mm_update_next_owner+0x7c0/0x7c0 [ 100.942478][ T9576] ? __x64_sys_watch_devices+0x1e4/0x290 [ 100.948102][ T9576] ? rcu_read_lock_sched_held+0x9c/0xd0 [ 100.953851][ T9576] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 100.959826][ T9576] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 100.965269][ T9576] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 100.970713][ T9576] do_group_exit+0x135/0x360 [ 100.975301][ T9576] __x64_sys_exit_group+0x44/0x50 [ 100.980324][ T9576] do_syscall_64+0xfa/0x790 [ 100.984854][ T9576] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 100.990734][ T9576] RIP: 0033:0x43edb8 [ 100.994627][ T9576] Code: Bad RIP value. [ 100.998681][ T9576] RSP: 002b:00007fffd28673f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 101.007070][ T9576] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043edb8 [ 101.015035][ T9576] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 101.022983][ T9576] RBP: 00000000004be5c8 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 101.030942][ T9576] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 101.038889][ T9576] R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000 [ 101.048419][ T9576] Kernel Offset: disabled [ 101.052798][ T9576] Rebooting in 86400 seconds..