[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 77.412316][ T27] audit: type=1800 audit(1584507660.609:25): pid=9341 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 77.446357][ T27] audit: type=1800 audit(1584507660.619:26): pid=9341 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 77.489038][ T27] audit: type=1800 audit(1584507660.619:27): pid=9341 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 '10.128.0.14' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 87.483512][ T9493] IPVS: ftp: loaded support on port[0] = 21 [ 87.515607][ T9493] netlink: 16 bytes leftover after parsing attributes in process `syz-executor199'. [ 87.577361][ T9493] ------------[ cut here ]------------ [ 87.582885][ T9493] refcount_t: underflow; use-after-free. [ 87.589092][ T9493] WARNING: CPU: 0 PID: 9493 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 [ 87.598864][ T9493] Kernel panic - not syncing: panic_on_warn set ... [ 87.605442][ T9493] CPU: 0 PID: 9493 Comm: syz-executor199 Not tainted 5.6.0-rc6-syzkaller #0 [ 87.614089][ T9493] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 87.624236][ T9493] Call Trace: [ 87.627518][ T9493] dump_stack+0x188/0x20d [ 87.631834][ T9493] ? refcount_warn_saturate+0x170/0x1e0 [ 87.637359][ T9493] panic+0x2e3/0x75c [ 87.641247][ T9493] ? add_taint.cold+0x16/0x16 [ 87.645936][ T9493] ? __probe_kernel_read+0x188/0x1d0 [ 87.651644][ T9493] ? __warn.cold+0x14/0x35 [ 87.656045][ T9493] ? __warn+0xd5/0x1c8 [ 87.660716][ T9493] ? refcount_warn_saturate+0x1d1/0x1e0 [ 87.666256][ T9493] __warn.cold+0x2f/0x35 [ 87.670532][ T9493] ? refcount_warn_saturate+0x1d1/0x1e0 [ 87.676081][ T9493] report_bug+0x27b/0x2f0 [ 87.680406][ T9493] do_error_trap+0x12b/0x220 [ 87.684974][ T9493] ? refcount_warn_saturate+0x1d1/0x1e0 [ 87.690757][ T9493] do_invalid_op+0x32/0x40 [ 87.695321][ T9493] ? refcount_warn_saturate+0x1d1/0x1e0 [ 87.700912][ T9493] invalid_op+0x23/0x30 [ 87.705100][ T9493] RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 [ 87.711237][ T9493] Code: e9 db fe ff ff 48 89 df e8 0c 06 20 fe e9 8a fe ff ff e8 d2 47 e3 fd 48 c7 c7 00 aa 51 88 c6 05 24 4e d2 06 01 e8 b7 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 [ 87.731185][ T9493] RSP: 0018:ffffc90001797d38 EFLAGS: 00010286 [ 87.737237][ T9493] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 87.745213][ T9493] RDX: 0000000000000000 RSI: ffffffff815c06c1 RDI: fffff520002f2f99 [ 87.753165][ T9493] RBP: 0000000000000003 R08: ffff888094d64080 R09: 0000000000000000 [ 87.761146][ T9493] R10: 0000000000000000 R11: 0000000000000000 R12: ffff888091384040 [ 87.769192][ T9493] R13: ffff888091384044 R14: 00000000000002ab R15: ffff88809762cbc0 [ 87.777177][ T9493] ? vprintk_func+0x81/0x17e [ 87.781757][ T9493] ? refcount_warn_saturate+0x1d1/0x1e0 [ 87.787371][ T9493] free_nsproxy+0x445/0x4a0 [ 87.791854][ T9493] switch_task_namespaces+0xaa/0xc0 [ 87.797037][ T9493] do_exit+0xb2f/0x2dd0 [ 87.801180][ T9493] ? mm_update_next_owner+0x7a0/0x7a0 [ 87.806530][ T9493] ? up_read+0x1ab/0x750 [ 87.810750][ T9493] ? mark_held_locks+0x9f/0xe0 [ 87.815492][ T9493] ? down_read_non_owner+0x470/0x470 [ 87.820757][ T9493] ? handle_mm_fault+0x491/0xa10 [ 87.826165][ T9493] do_group_exit+0x125/0x340 [ 87.831791][ T9493] __x64_sys_exit_group+0x3a/0x50 [ 87.836825][ T9493] do_syscall_64+0xf6/0x7d0 [ 87.841377][ T9493] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 87.847268][ T9493] RIP: 0033:0x43f998 [ 87.851152][ T9493] Code: Bad RIP value. [ 87.855385][ T9493] RSP: 002b:00007ffc07c4c5d8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 87.863784][ T9493] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 000000000043f998 [ 87.871824][ T9493] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 87.879774][ T9493] RBP: 00000000004bfa10 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 87.887722][ T9493] R10: 0000000120080522 R11: 0000000000000246 R12: 0000000000000001 [ 87.895731][ T9493] R13: 00000000006d11c0 R14: 0000000000000000 R15: 0000000000000000 [ 87.905712][ T9493] Kernel Offset: disabled [ 87.910107][ T9493] Rebooting in 86400 seconds..