[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 64.302607][ T27] audit: type=1800 audit(1585437298.927:25): pid=9304 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 64.335294][ T27] audit: type=1800 audit(1585437298.937:26): pid=9304 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 64.372733][ T27] audit: type=1800 audit(1585437298.937:27): pid=9304 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 '10.128.0.60' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 89.044345][ T9460] IPVS: ftp: loaded support on port[0] = 21 [ 89.078280][ T9460] netlink: 16 bytes leftover after parsing attributes in process `syz-executor698'. [ 89.136527][ T9460] ------------[ cut here ]------------ [ 89.142550][ T9460] refcount_t: underflow; use-after-free. [ 89.148572][ T9460] WARNING: CPU: 1 PID: 9460 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 [ 89.157942][ T9460] Kernel panic - not syncing: panic_on_warn set ... [ 89.164530][ T9460] CPU: 1 PID: 9460 Comm: syz-executor698 Not tainted 5.6.0-rc3-next-20200228-syzkaller #0 [ 89.174407][ T9460] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 89.184468][ T9460] Call Trace: [ 89.187746][ T9460] dump_stack+0x188/0x20d [ 89.192109][ T9460] ? refcount_warn_saturate+0x150/0x1e0 [ 89.197650][ T9460] panic+0x2e3/0x75c [ 89.201534][ T9460] ? add_taint.cold+0x16/0x16 [ 89.206199][ T9460] ? __probe_kernel_read+0x188/0x1d0 [ 89.211474][ T9460] ? __warn.cold+0x14/0x35 [ 89.215872][ T9460] ? __warn+0xd5/0x1c8 [ 89.219935][ T9460] ? refcount_warn_saturate+0x1d1/0x1e0 [ 89.225461][ T9460] __warn.cold+0x2f/0x35 [ 89.229694][ T9460] ? refcount_warn_saturate+0x1d1/0x1e0 [ 89.235218][ T9460] report_bug+0x27b/0x2f0 [ 89.239538][ T9460] do_error_trap+0x12b/0x220 [ 89.244108][ T9460] ? refcount_warn_saturate+0x1d1/0x1e0 [ 89.249663][ T9460] do_invalid_op+0x32/0x40 [ 89.254063][ T9460] ? refcount_warn_saturate+0x1d1/0x1e0 [ 89.259645][ T9460] invalid_op+0x23/0x30 [ 89.263791][ T9460] RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 [ 89.270044][ T9460] Code: e9 db fe ff ff 48 89 df e8 1c e7 1f fe e9 8a fe ff ff e8 12 c6 e2 fd 48 c7 c7 40 db 71 88 c6 05 b6 a9 f1 06 01 e8 77 91 b4 fd <0f> 0b e9 af fe ff ff 0f 1f 84 00 00 00 00 00 41 56 41 55 41 54 55 [ 89.289665][ T9460] RSP: 0018:ffffc90002047d38 EFLAGS: 00010286 [ 89.295725][ T9460] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 89.304021][ T9460] RDX: 0000000000000000 RSI: ffffffff815c4e91 RDI: fffff52000408f99 [ 89.311980][ T9460] RBP: 0000000000000003 R08: ffff8880a80ca540 R09: 0000000000000000 [ 89.319934][ T9460] R10: 0000000000000000 R11: 0000000000000000 R12: ffff88809183c040 [ 89.327887][ T9460] R13: ffff88809183c044 R14: 00000000000002ab R15: ffff8880943ec5c0 [ 89.336204][ T9460] ? vprintk_func+0x81/0x17e [ 89.340809][ T9460] ? refcount_warn_saturate+0x1d1/0x1e0 [ 89.346446][ T9460] free_nsproxy+0x445/0x4a0 [ 89.350974][ T9460] switch_task_namespaces+0xaa/0xc0 [ 89.356394][ T9460] do_exit+0xb4e/0x2e10 [ 89.361121][ T9460] ? mm_update_next_owner+0x7a0/0x7a0 [ 89.366602][ T9460] ? up_read+0x1a8/0x750 [ 89.370830][ T9460] ? down_read_nested+0x430/0x430 [ 89.375928][ T9460] ? handle_mm_fault+0x29e/0x660 [ 89.380853][ T9460] do_group_exit+0x125/0x340 [ 89.385439][ T9460] __x64_sys_exit_group+0x3a/0x50 [ 89.390446][ T9460] do_syscall_64+0xf6/0x790 [ 89.395023][ T9460] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 89.401126][ T9460] RIP: 0033:0x43f998 [ 89.405003][ T9460] 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 [ 89.426001][ T9460] RSP: 002b:00007ffc1cb660e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 89.434398][ T9460] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 000000000043f998 [ 89.442371][ T9460] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 89.450332][ T9460] RBP: 00000000004bfa10 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 89.458293][ T9460] R10: 0000000120080522 R11: 0000000000000246 R12: 0000000000000001 [ 89.466611][ T9460] R13: 00000000006d11c0 R14: 0000000000000000 R15: 0000000000000000 [ 89.476271][ T9460] Kernel Offset: disabled [ 89.480769][ T9460] Rebooting in 86400 seconds..