[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 67.487850][ T27] audit: type=1800 audit(1584419449.828:25): pid=9503 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 67.507972][ T27] audit: type=1800 audit(1584419449.838:26): pid=9503 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 67.557191][ T27] audit: type=1800 audit(1584419449.838:27): pid=9503 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 '10.128.0.204' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 76.328004][ T9659] IPVS: ftp: loaded support on port[0] = 21 [ 76.356963][ T9659] netlink: 16 bytes leftover after parsing attributes in process `syz-executor574'. [ 76.428807][ T9659] ------------[ cut here ]------------ [ 76.434491][ T9659] refcount_t: underflow; use-after-free. [ 76.440507][ T9659] WARNING: CPU: 1 PID: 9659 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 [ 76.449891][ T9659] Kernel panic - not syncing: panic_on_warn set ... [ 76.456600][ T9659] CPU: 1 PID: 9659 Comm: syz-executor574 Not tainted 5.6.0-rc6-syzkaller #0 [ 76.465349][ T9659] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 76.475397][ T9659] Call Trace: [ 76.478696][ T9659] dump_stack+0x188/0x20d [ 76.483012][ T9659] ? refcount_warn_saturate+0x170/0x1e0 [ 76.488557][ T9659] panic+0x2e3/0x75c [ 76.492445][ T9659] ? add_taint.cold+0x16/0x16 [ 76.497110][ T9659] ? __probe_kernel_read+0x188/0x1d0 [ 76.502374][ T9659] ? __warn.cold+0x14/0x35 [ 76.506856][ T9659] ? __warn+0xd5/0x1c8 [ 76.510908][ T9659] ? refcount_warn_saturate+0x1d1/0x1e0 [ 76.516440][ T9659] __warn.cold+0x2f/0x35 [ 76.520677][ T9659] ? refcount_warn_saturate+0x1d1/0x1e0 [ 76.526204][ T9659] report_bug+0x27b/0x2f0 [ 76.530529][ T9659] do_error_trap+0x12b/0x220 [ 76.535097][ T9659] ? refcount_warn_saturate+0x1d1/0x1e0 [ 76.540626][ T9659] do_invalid_op+0x32/0x40 [ 76.545037][ T9659] ? refcount_warn_saturate+0x1d1/0x1e0 [ 76.555572][ T9659] invalid_op+0x23/0x30 [ 76.559753][ T9659] RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 [ 76.565905][ T9659] 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 [ 76.585523][ T9659] RSP: 0018:ffffc90001d67d28 EFLAGS: 00010282 [ 76.591575][ T9659] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 76.599538][ T9659] RDX: 0000000000000000 RSI: ffffffff815c06c1 RDI: fffff520003acf97 [ 76.607509][ T9659] RBP: 0000000000000003 R08: ffff88808b2825c0 R09: 0000000000000000 [ 76.615470][ T9659] R10: 0000000000000000 R11: 0000000000000000 R12: ffff88809e1b0040 [ 76.623452][ T9659] R13: ffff88809e1b0044 R14: 0000000000000282 R15: ffff888093bfae80 [ 76.631470][ T9659] ? vprintk_func+0x81/0x17e [ 76.636076][ T9659] ? refcount_warn_saturate+0x1d1/0x1e0 [ 76.641768][ T9659] free_nsproxy+0x445/0x4a0 [ 76.646289][ T9659] switch_task_namespaces+0xaa/0xc0 [ 76.651494][ T9659] do_exit+0xb2f/0x2dd0 [ 76.655657][ T9659] ? mm_update_next_owner+0x7a0/0x7a0 [ 76.661016][ T9659] ? up_read+0x1ab/0x750 [ 76.665240][ T9659] ? mark_held_locks+0x9f/0xe0 [ 76.669996][ T9659] ? down_read_non_owner+0x470/0x470 [ 76.675277][ T9659] do_group_exit+0x125/0x340 [ 76.679872][ T9659] __ia32_sys_exit_group+0x3a/0x50 [ 76.684975][ T9659] do_fast_syscall_32+0x270/0xe8f [ 76.690004][ T9659] entry_SYSENTER_compat+0x70/0x7f [ 76.696595][ T9659] Kernel Offset: disabled [ 76.700974][ T9659] Rebooting in 86400 seconds..