[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 78.850526][ T27] audit: type=1800 audit(1584508271.014:25): pid=9448 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 78.870246][ T27] audit: type=1800 audit(1584508271.014:26): pid=9448 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 78.898060][ T27] audit: type=1800 audit(1584508271.014:27): pid=9448 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 '10.128.0.140' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 105.013565][ T9603] IPVS: ftp: loaded support on port[0] = 21 [ 105.044618][ T9603] netlink: 16 bytes leftover after parsing attributes in process `syz-executor185'. [ 105.087917][ T9603] ------------[ cut here ]------------ [ 105.093441][ T9603] refcount_t: underflow; use-after-free. [ 105.099699][ T9603] WARNING: CPU: 1 PID: 9603 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 [ 105.109085][ T9603] Kernel panic - not syncing: panic_on_warn set ... [ 105.115710][ T9603] CPU: 1 PID: 9603 Comm: syz-executor185 Not tainted 5.6.0-rc6-syzkaller #0 [ 105.124356][ T9603] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 105.134434][ T9603] Call Trace: [ 105.137720][ T9603] dump_stack+0x188/0x20d [ 105.142037][ T9603] ? refcount_warn_saturate+0x170/0x1e0 [ 105.147569][ T9603] panic+0x2e3/0x75c [ 105.151449][ T9603] ? add_taint.cold+0x16/0x16 [ 105.156119][ T9603] ? __probe_kernel_read+0x188/0x1d0 [ 105.161389][ T9603] ? __warn.cold+0x14/0x35 [ 105.165805][ T9603] ? __warn+0xd5/0x1c8 [ 105.169910][ T9603] ? refcount_warn_saturate+0x1d1/0x1e0 [ 105.175498][ T9603] __warn.cold+0x2f/0x35 [ 105.179751][ T9603] ? refcount_warn_saturate+0x1d1/0x1e0 [ 105.185283][ T9603] report_bug+0x27b/0x2f0 [ 105.189606][ T9603] do_error_trap+0x12b/0x220 [ 105.194179][ T9603] ? refcount_warn_saturate+0x1d1/0x1e0 [ 105.199723][ T9603] do_invalid_op+0x32/0x40 [ 105.204123][ T9603] ? refcount_warn_saturate+0x1d1/0x1e0 [ 105.209653][ T9603] invalid_op+0x23/0x30 [ 105.213814][ T9603] RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 [ 105.219960][ T9603] 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 [ 105.239554][ T9603] RSP: 0018:ffffc90001da7d28 EFLAGS: 00010282 [ 105.245606][ T9603] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 105.253575][ T9603] RDX: 0000000000000000 RSI: ffffffff815c06c1 RDI: fffff520003b4f97 [ 105.261528][ T9603] RBP: 0000000000000003 R08: ffff8880a639a240 R09: 0000000000000000 [ 105.269483][ T9603] R10: 0000000000000000 R11: 0000000000000000 R12: ffff888094bb8040 [ 105.277437][ T9603] R13: ffff888094bb8044 R14: 0000000000000282 R15: ffff88808f564a00 [ 105.285428][ T9603] ? vprintk_func+0x81/0x17e [ 105.290011][ T9603] ? refcount_warn_saturate+0x1d1/0x1e0 [ 105.295542][ T9603] free_nsproxy+0x445/0x4a0 [ 105.300030][ T9603] switch_task_namespaces+0xaa/0xc0 [ 105.305222][ T9603] do_exit+0xb2f/0x2dd0 [ 105.309370][ T9603] ? mm_update_next_owner+0x7a0/0x7a0 [ 105.314734][ T9603] ? up_read+0x1ab/0x750 [ 105.318959][ T9603] ? mark_held_locks+0x9f/0xe0 [ 105.323708][ T9603] ? down_read_non_owner+0x470/0x470 [ 105.328983][ T9603] do_group_exit+0x125/0x340 [ 105.333561][ T9603] __ia32_sys_exit_group+0x3a/0x50 [ 105.338660][ T9603] do_fast_syscall_32+0x270/0xe8f [ 105.343675][ T9603] entry_SYSENTER_compat+0x70/0x7f [ 105.350453][ T9603] Kernel Offset: disabled [ 105.354898][ T9603] Rebooting in 86400 seconds..