[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 83.381599][ T28] audit: type=1800 audit(1583864598.464:25): pid=9334 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 83.401466][ T28] audit: type=1800 audit(1583864598.474:26): pid=9334 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 83.439678][ T28] audit: type=1800 audit(1583864598.474:27): pid=9334 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 '10.128.0.109' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 93.187009][ T9486] IPVS: ftp: loaded support on port[0] = 21 [ 93.218252][ T9486] netlink: 16 bytes leftover after parsing attributes in process `syz-executor430'. [ 93.263967][ T9486] ------------[ cut here ]------------ [ 93.269459][ T9486] refcount_t: underflow; use-after-free. [ 93.275507][ T9486] WARNING: CPU: 0 PID: 9486 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 [ 93.284877][ T9486] Kernel panic - not syncing: panic_on_warn set ... [ 93.291454][ T9486] CPU: 0 PID: 9486 Comm: syz-executor430 Not tainted 5.6.0-rc3-syzkaller #0 [ 93.300262][ T9486] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 93.310313][ T9486] Call Trace: [ 93.313605][ T9486] dump_stack+0x188/0x20d [ 93.317933][ T9486] ? refcount_warn_saturate+0x1b0/0x1e0 [ 93.323503][ T9486] panic+0x2e3/0x75c [ 93.327378][ T9486] ? add_taint.cold+0x16/0x16 [ 93.332056][ T9486] ? __probe_kernel_read+0x188/0x1d0 [ 93.337316][ T9486] ? __warn.cold+0x14/0x35 [ 93.341709][ T9486] ? __warn+0xd5/0x1c8 [ 93.345759][ T9486] ? refcount_warn_saturate+0x1d1/0x1e0 [ 93.351278][ T9486] __warn.cold+0x2f/0x35 [ 93.355500][ T9486] ? refcount_warn_saturate+0x1d1/0x1e0 [ 93.361065][ T9486] report_bug+0x27b/0x2f0 [ 93.365378][ T9486] do_error_trap+0x12b/0x220 [ 93.369968][ T9486] ? refcount_warn_saturate+0x1d1/0x1e0 [ 93.375499][ T9486] do_invalid_op+0x32/0x40 [ 93.379897][ T9486] ? refcount_warn_saturate+0x1d1/0x1e0 [ 93.385527][ T9486] invalid_op+0x23/0x30 [ 93.389661][ T9486] RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 [ 93.395792][ T9486] Code: e9 db fe ff ff 48 89 df e8 3c 22 21 fe e9 8a fe ff ff e8 82 7c e4 fd 48 c7 c7 40 a3 51 88 c6 05 f6 8c d3 06 01 e8 b7 8f b6 fd <0f> 0b e9 af fe ff ff 0f 1f 84 00 00 00 00 00 41 56 41 55 41 54 55 [ 93.415373][ T9486] RSP: 0018:ffffc90002787d50 EFLAGS: 00010286 [ 93.421415][ T9486] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 93.429365][ T9486] RDX: 0000000000000000 RSI: ffffffff815bf411 RDI: fffff520004f0f9c [ 93.437328][ T9486] RBP: 0000000000000003 R08: ffff8880a8ad8300 R09: 0000000000000000 [ 93.445279][ T9486] R10: 0000000000000000 R11: 0000000000000000 R12: ffff888098940040 [ 93.453243][ T9486] R13: ffff888098940044 R14: 0000000000000001 R15: 00000000000002aa [ 93.461210][ T9486] ? vprintk_func+0x81/0x17e [ 93.465804][ T9486] free_nsproxy+0x445/0x4a0 [ 93.470291][ T9486] switch_task_namespaces+0xaa/0xc0 [ 93.475481][ T9486] do_exit+0xb54/0x2db0 [ 93.479623][ T9486] ? mm_update_next_owner+0x7a0/0x7a0 [ 93.484974][ T9486] ? up_read+0x1ab/0x750 [ 93.489220][ T9486] ? mark_held_locks+0x9f/0xe0 [ 93.494017][ T9486] ? down_read_non_owner+0x470/0x470 [ 93.499288][ T9486] ? handle_mm_fault+0x491/0xa10 [ 93.504267][ T9486] do_group_exit+0x125/0x340 [ 93.508848][ T9486] __x64_sys_exit_group+0x3a/0x50 [ 93.513886][ T9486] do_syscall_64+0xf6/0x790 [ 93.518388][ T9486] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 93.524260][ T9486] RIP: 0033:0x43f9d8 [ 93.528161][ T9486] Code: 24 2c 00 00 00 00 c7 44 24 28 00 00 00 00 80 3a 2e 0f 84 7b 01 00 00 44 0f b6 02 41 80 f8 5a 0f 84 4d 01 00 00 41 80 f8 2d 0f <85> eb 00 00 00 48 8d 74 24 34 48 8d 7c 24 38 83 e9 01 48 83 c2 01 [ 93.547845][ T9486] RSP: 002b:00007fffcdfdb6a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 93.556233][ T9486] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 000000000043f9d8 [ 93.564195][ T9486] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 93.572145][ T9486] RBP: 00000000004bfa50 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 93.580112][ T9486] R10: 0000000120080522 R11: 0000000000000246 R12: 0000000000000001 [ 93.588063][ T9486] R13: 00000000006d21c0 R14: 0000000000000000 R15: 0000000000000000 [ 93.597499][ T9486] Kernel Offset: disabled [ 93.601876][ T9486] Rebooting in 86400 seconds..