[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 67.348898][ T27] audit: type=1800 audit(1584502725.165:25): pid=9357 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 67.380247][ T27] audit: type=1800 audit(1584502725.175:26): pid=9357 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 67.423849][ T27] audit: type=1800 audit(1584502725.175:27): pid=9357 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 '10.128.15.217' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 79.367207][ T9511] IPVS: ftp: loaded support on port[0] = 21 [ 79.398328][ T9511] netlink: 16 bytes leftover after parsing attributes in process `syz-executor781'. [ 79.461200][ T9511] ------------[ cut here ]------------ [ 79.466685][ T9511] refcount_t: underflow; use-after-free. [ 79.472735][ T9511] WARNING: CPU: 1 PID: 9511 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 [ 79.482131][ T9511] Kernel panic - not syncing: panic_on_warn set ... [ 79.488754][ T9511] CPU: 1 PID: 9511 Comm: syz-executor781 Not tainted 5.6.0-rc6-syzkaller #0 [ 79.497420][ T9511] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 79.507479][ T9511] Call Trace: [ 79.510761][ T9511] dump_stack+0x188/0x20d [ 79.515075][ T9511] ? refcount_warn_saturate+0x170/0x1e0 [ 79.520602][ T9511] panic+0x2e3/0x75c [ 79.524522][ T9511] ? add_taint.cold+0x16/0x16 [ 79.529225][ T9511] ? __probe_kernel_read+0x188/0x1d0 [ 79.534501][ T9511] ? __warn.cold+0x14/0x35 [ 79.538896][ T9511] ? __warn+0xd5/0x1c8 [ 79.542946][ T9511] ? refcount_warn_saturate+0x1d1/0x1e0 [ 79.548473][ T9511] __warn.cold+0x2f/0x35 [ 79.552697][ T9511] ? refcount_warn_saturate+0x1d1/0x1e0 [ 79.558240][ T9511] report_bug+0x27b/0x2f0 [ 79.562584][ T9511] do_error_trap+0x12b/0x220 [ 79.567229][ T9511] ? refcount_warn_saturate+0x1d1/0x1e0 [ 79.572781][ T9511] do_invalid_op+0x32/0x40 [ 79.577188][ T9511] ? refcount_warn_saturate+0x1d1/0x1e0 [ 79.582726][ T9511] invalid_op+0x23/0x30 [ 79.586871][ T9511] RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 [ 79.593065][ T9511] 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 [ 79.612668][ T9511] RSP: 0018:ffffc90002357d38 EFLAGS: 00010286 [ 79.618718][ T9511] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 79.626734][ T9511] RDX: 0000000000000000 RSI: ffffffff815c06c1 RDI: fffff5200046af99 [ 79.634694][ T9511] RBP: 0000000000000003 R08: ffff8880976a8440 R09: 0000000000000000 [ 79.642649][ T9511] R10: 0000000000000000 R11: 0000000000000000 R12: ffff888094cd2040 [ 79.650638][ T9511] R13: ffff888094cd2044 R14: 00000000000002ab R15: ffff8880a83c1240 [ 79.658612][ T9511] ? vprintk_func+0x81/0x17e [ 79.663202][ T9511] ? refcount_warn_saturate+0x1d1/0x1e0 [ 79.668752][ T9511] free_nsproxy+0x445/0x4a0 [ 79.673251][ T9511] switch_task_namespaces+0xaa/0xc0 [ 79.678435][ T9511] do_exit+0xb2f/0x2dd0 [ 79.682598][ T9511] ? mm_update_next_owner+0x7a0/0x7a0 [ 79.688077][ T9511] ? up_read+0x1ab/0x750 [ 79.692311][ T9511] ? mark_held_locks+0x9f/0xe0 [ 79.697063][ T9511] ? down_read_non_owner+0x470/0x470 [ 79.702336][ T9511] ? handle_mm_fault+0x491/0xa10 [ 79.707261][ T9511] do_group_exit+0x125/0x340 [ 79.711838][ T9511] __x64_sys_exit_group+0x3a/0x50 [ 79.716887][ T9511] do_syscall_64+0xf6/0x7d0 [ 79.721379][ T9511] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 79.727249][ T9511] RIP: 0033:0x43f998 [ 79.731137][ T9511] Code: 24 38 80 f9 3a 0f 85 5f 01 00 00 48 8d 74 24 34 48 8d 7c 24 38 83 ea 01 89 54 24 34 e8 61 f8 ff ff 83 f8 3c 41 89 c1 0f 87 3d <01> 00 00 8b 4c 24 34 85 c9 0f 8e 59 01 00 00 48 8b 54 24 38 c7 44 [ 79.750719][ T9511] RSP: 002b:00007ffd2bfbb708 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 79.759176][ T9511] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 000000000043f998 [ 79.767145][ T9511] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 79.775129][ T9511] RBP: 00000000004bfa10 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 79.783126][ T9511] R10: 0000000120080522 R11: 0000000000000246 R12: 0000000000000001 [ 79.791080][ T9511] R13: 00000000006d11c0 R14: 0000000000000000 R15: 0000000000000000 [ 79.800686][ T9511] Kernel Offset: disabled [ 79.805081][ T9511] Rebooting in 86400 seconds..