[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 74.048562][ T27] audit: type=1800 audit(1584227009.704:25): pid=9294 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 74.080308][ T27] audit: type=1800 audit(1584227009.714:26): pid=9294 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 74.132406][ T27] audit: type=1800 audit(1584227009.714:27): pid=9294 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 '10.128.0.33' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 86.799044][ T9447] IPVS: ftp: loaded support on port[0] = 21 [ 86.830506][ T9447] netlink: 16 bytes leftover after parsing attributes in process `syz-executor347'. [ 86.901609][ T9447] ------------[ cut here ]------------ [ 86.907107][ T9447] refcount_t: underflow; use-after-free. [ 86.913110][ T9447] WARNING: CPU: 0 PID: 9447 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 [ 86.922483][ T9447] Kernel panic - not syncing: panic_on_warn set ... [ 86.929072][ T9447] CPU: 0 PID: 9447 Comm: syz-executor347 Not tainted 5.6.0-rc5-syzkaller #0 [ 86.937743][ T9447] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 86.947795][ T9447] Call Trace: [ 86.951097][ T9447] dump_stack+0x188/0x20d [ 86.955439][ T9447] ? refcount_warn_saturate+0x130/0x1e0 [ 86.960984][ T9447] panic+0x2e3/0x75c [ 86.964869][ T9447] ? add_taint.cold+0x16/0x16 [ 86.969541][ T9447] ? __probe_kernel_read+0x188/0x1d0 [ 86.974823][ T9447] ? __warn.cold+0x14/0x35 [ 86.979229][ T9447] ? __warn+0xd5/0x1c8 [ 86.983287][ T9447] ? refcount_warn_saturate+0x1d1/0x1e0 [ 86.988825][ T9447] __warn.cold+0x2f/0x35 [ 86.993072][ T9447] ? refcount_warn_saturate+0x1d1/0x1e0 [ 86.998617][ T9447] report_bug+0x27b/0x2f0 [ 87.002947][ T9447] do_error_trap+0x12b/0x220 [ 87.007520][ T9447] ? refcount_warn_saturate+0x1d1/0x1e0 [ 87.013071][ T9447] do_invalid_op+0x32/0x40 [ 87.017505][ T9447] ? refcount_warn_saturate+0x1d1/0x1e0 [ 87.023037][ T9447] invalid_op+0x23/0x30 [ 87.027343][ T9447] RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 [ 87.033490][ T9447] Code: e9 db fe ff ff 48 89 df e8 6c 06 20 fe e9 8a fe ff ff e8 32 48 e3 fd 48 c7 c7 40 aa 51 88 c6 05 a4 5d d2 06 01 e8 77 58 b5 fd <0f> 0b e9 af fe ff ff 0f 1f 84 00 00 00 00 00 41 56 41 55 41 54 55 [ 87.053171][ T9447] RSP: 0018:ffffc90007807d38 EFLAGS: 00010286 [ 87.059231][ T9447] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 87.067187][ T9447] RDX: 0000000000000000 RSI: ffffffff815bf511 RDI: fffff52000f00f99 [ 87.075187][ T9447] RBP: 0000000000000003 R08: ffff888094102440 R09: 0000000000000000 [ 87.083152][ T9447] R10: 0000000000000000 R11: 0000000000000000 R12: ffff888093b3a040 [ 87.091120][ T9447] R13: ffff888093b3a044 R14: 00000000000002ac R15: ffff888096522b80 [ 87.099107][ T9447] ? vprintk_func+0x81/0x17e [ 87.103686][ T9447] ? refcount_warn_saturate+0x1d1/0x1e0 [ 87.109211][ T9447] free_nsproxy+0x445/0x4a0 [ 87.113714][ T9447] switch_task_namespaces+0xaa/0xc0 [ 87.118930][ T9447] do_exit+0xb2f/0x2dd0 [ 87.123079][ T9447] ? mm_update_next_owner+0x7a0/0x7a0 [ 87.128436][ T9447] ? up_read+0x1ab/0x750 [ 87.132659][ T9447] ? mark_held_locks+0x9f/0xe0 [ 87.137407][ T9447] ? down_read_non_owner+0x470/0x470 [ 87.142683][ T9447] ? handle_mm_fault+0x491/0xa10 [ 87.147619][ T9447] do_group_exit+0x125/0x340 [ 87.152195][ T9447] __x64_sys_exit_group+0x3a/0x50 [ 87.157202][ T9447] do_syscall_64+0xf6/0x7d0 [ 87.161697][ T9447] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 87.167628][ T9447] RIP: 0033:0x43f998 [ 87.171509][ T9447] Code: Bad RIP value. [ 87.175559][ T9447] RSP: 002b:00007fff31404d28 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 87.183981][ T9447] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 000000000043f998 [ 87.191933][ T9447] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 87.199889][ T9447] RBP: 00000000004bfa10 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 87.207836][ T9447] R10: 0000000120080522 R11: 0000000000000246 R12: 0000000000000001 [ 87.215783][ T9447] R13: 00000000006d11c0 R14: 0000000000000000 R15: 0000000000000000 [ 87.225075][ T9447] Kernel Offset: disabled [ 87.229452][ T9447] Rebooting in 86400 seconds..