[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 80.679351][ T27] audit: type=1800 audit(1584307948.460:25): pid=9589 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 80.699293][ T27] audit: type=1800 audit(1584307948.460:26): pid=9589 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 80.725654][ T27] audit: type=1800 audit(1584307948.470:27): pid=9589 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 '10.128.1.57' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 105.206665][ T9743] IPVS: ftp: loaded support on port[0] = 21 [ 105.238709][ T9743] netlink: 16 bytes leftover after parsing attributes in process `syz-executor201'. [ 105.287362][ T9743] ------------[ cut here ]------------ [ 105.292998][ T9743] refcount_t: underflow; use-after-free. [ 105.299234][ T9743] WARNING: CPU: 0 PID: 9743 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 [ 105.308745][ T9743] Kernel panic - not syncing: panic_on_warn set ... [ 105.315319][ T9743] CPU: 0 PID: 9743 Comm: syz-executor201 Not tainted 5.6.0-rc5-syzkaller #0 [ 105.323976][ T9743] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 105.334078][ T9743] Call Trace: [ 105.337369][ T9743] dump_stack+0x188/0x20d [ 105.341840][ T9743] ? refcount_warn_saturate+0x130/0x1e0 [ 105.347375][ T9743] panic+0x2e3/0x75c [ 105.351349][ T9743] ? add_taint.cold+0x16/0x16 [ 105.356178][ T9743] ? __probe_kernel_read+0x188/0x1d0 [ 105.361457][ T9743] ? __warn.cold+0x14/0x35 [ 105.365934][ T9743] ? __warn+0xd5/0x1c8 [ 105.370001][ T9743] ? refcount_warn_saturate+0x1d1/0x1e0 [ 105.375659][ T9743] __warn.cold+0x2f/0x35 [ 105.379930][ T9743] ? refcount_warn_saturate+0x1d1/0x1e0 [ 105.385483][ T9743] report_bug+0x27b/0x2f0 [ 105.389892][ T9743] do_error_trap+0x12b/0x220 [ 105.394542][ T9743] ? refcount_warn_saturate+0x1d1/0x1e0 [ 105.400097][ T9743] do_invalid_op+0x32/0x40 [ 105.404497][ T9743] ? refcount_warn_saturate+0x1d1/0x1e0 [ 105.410050][ T9743] invalid_op+0x23/0x30 [ 105.414203][ T9743] RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 [ 105.420377][ T9743] 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 e4 4d 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 [ 105.440091][ T9743] RSP: 0018:ffffc900020c7d28 EFLAGS: 00010282 [ 105.446148][ T9743] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 105.454118][ T9743] RDX: 0000000000000000 RSI: ffffffff815c0511 RDI: fffff52000418f97 [ 105.462085][ T9743] RBP: 0000000000000003 R08: ffff8880978a8000 R09: 0000000000000000 [ 105.470139][ T9743] R10: 0000000000000000 R11: 0000000000000000 R12: ffff88809693c040 [ 105.478098][ T9743] R13: ffff88809693c044 R14: 0000000000000282 R15: ffff8880a011e400 [ 105.486070][ T9743] ? vprintk_func+0x81/0x17e [ 105.490749][ T9743] ? refcount_warn_saturate+0x1d1/0x1e0 [ 105.496288][ T9743] free_nsproxy+0x445/0x4a0 [ 105.500783][ T9743] switch_task_namespaces+0xaa/0xc0 [ 105.505983][ T9743] do_exit+0xb2f/0x2dd0 [ 105.510138][ T9743] ? mm_update_next_owner+0x7a0/0x7a0 [ 105.515505][ T9743] ? up_read+0x1ab/0x750 [ 105.519732][ T9743] ? mark_held_locks+0x9f/0xe0 [ 105.524478][ T9743] ? down_read_non_owner+0x470/0x470 [ 105.529749][ T9743] do_group_exit+0x125/0x340 [ 105.534325][ T9743] __ia32_sys_exit_group+0x3a/0x50 [ 105.539454][ T9743] do_fast_syscall_32+0x270/0xe8f [ 105.545281][ T9743] entry_SYSENTER_compat+0x70/0x7f [ 105.552171][ T9743] Kernel Offset: disabled [ 105.556571][ T9743] Rebooting in 86400 seconds..