[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 71.458090][ T27] audit: type=1800 audit(1584293177.173:25): pid=9465 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 71.477784][ T27] audit: type=1800 audit(1584293177.183:26): pid=9465 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 71.543422][ T27] audit: type=1800 audit(1584293177.183:27): pid=9465 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 '10.128.0.235' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 82.515171][ T9619] IPVS: ftp: loaded support on port[0] = 21 [ 82.543413][ T9619] netlink: 16 bytes leftover after parsing attributes in process `syz-executor427'. [ 82.601043][ T9619] ------------[ cut here ]------------ [ 82.606654][ T9619] refcount_t: underflow; use-after-free. [ 82.612883][ T9619] WARNING: CPU: 1 PID: 9619 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 [ 82.622257][ T9619] Kernel panic - not syncing: panic_on_warn set ... [ 82.628824][ T9619] CPU: 1 PID: 9619 Comm: syz-executor427 Not tainted 5.6.0-rc5-syzkaller #0 [ 82.637467][ T9619] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 82.647510][ T9619] Call Trace: [ 82.650807][ T9619] dump_stack+0x188/0x20d [ 82.655115][ T9619] ? refcount_warn_saturate+0x130/0x1e0 [ 82.660649][ T9619] panic+0x2e3/0x75c [ 82.664574][ T9619] ? add_taint.cold+0x16/0x16 [ 82.669264][ T9619] ? __probe_kernel_read+0x188/0x1d0 [ 82.674528][ T9619] ? __warn.cold+0x14/0x35 [ 82.678971][ T9619] ? __warn+0xd5/0x1c8 [ 82.683021][ T9619] ? refcount_warn_saturate+0x1d1/0x1e0 [ 82.688547][ T9619] __warn.cold+0x2f/0x35 [ 82.692773][ T9619] ? refcount_warn_saturate+0x1d1/0x1e0 [ 82.698297][ T9619] report_bug+0x27b/0x2f0 [ 82.702609][ T9619] do_error_trap+0x12b/0x220 [ 82.707175][ T9619] ? refcount_warn_saturate+0x1d1/0x1e0 [ 82.712700][ T9619] do_invalid_op+0x32/0x40 [ 82.717093][ T9619] ? refcount_warn_saturate+0x1d1/0x1e0 [ 82.722651][ T9619] invalid_op+0x23/0x30 [ 82.726787][ T9619] RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 [ 82.733063][ T9619] 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 [ 82.752654][ T9619] RSP: 0018:ffffc900020b7d28 EFLAGS: 00010282 [ 82.758810][ T9619] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 82.766769][ T9619] RDX: 0000000000000000 RSI: ffffffff815c0511 RDI: fffff52000416f97 [ 82.774724][ T9619] RBP: 0000000000000003 R08: ffff88809bc14100 R09: 0000000000000000 [ 82.782705][ T9619] R10: 0000000000000000 R11: 0000000000000000 R12: ffff88808df30040 [ 82.790655][ T9619] R13: ffff88808df30044 R14: 0000000000000283 R15: ffff8880a6ee2fc0 [ 82.798670][ T9619] ? vprintk_func+0x81/0x17e [ 82.803288][ T9619] ? refcount_warn_saturate+0x1d1/0x1e0 [ 82.808812][ T9619] free_nsproxy+0x445/0x4a0 [ 82.813307][ T9619] switch_task_namespaces+0xaa/0xc0 [ 82.818484][ T9619] do_exit+0xb2f/0x2dd0 [ 82.822627][ T9619] ? mm_update_next_owner+0x7a0/0x7a0 [ 82.827978][ T9619] ? up_read+0x1ab/0x750 [ 82.832226][ T9619] ? mark_held_locks+0x9f/0xe0 [ 82.836970][ T9619] ? down_read_non_owner+0x470/0x470 [ 82.842239][ T9619] do_group_exit+0x125/0x340 [ 82.846811][ T9619] __ia32_sys_exit_group+0x3a/0x50 [ 82.851902][ T9619] do_fast_syscall_32+0x270/0xe8f [ 82.856908][ T9619] entry_SYSENTER_compat+0x70/0x7f [ 82.863446][ T9619] Kernel Offset: disabled [ 82.867827][ T9619] Rebooting in 86400 seconds..