[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 78.250579][ T27] audit: type=1800 audit(1584114792.666:25): pid=9437 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 78.271466][ T27] audit: type=1800 audit(1584114792.676:26): pid=9437 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 78.325645][ T27] audit: type=1800 audit(1584114792.676:27): pid=9437 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 '10.128.0.174' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 105.591112][ T9590] IPVS: ftp: loaded support on port[0] = 21 [ 105.620092][ T9590] netlink: 16 bytes leftover after parsing attributes in process `syz-executor796'. [ 105.682343][ T9590] ------------[ cut here ]------------ [ 105.687838][ T9590] refcount_t: underflow; use-after-free. [ 105.693889][ T9590] WARNING: CPU: 0 PID: 9590 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 [ 105.703268][ T9590] Kernel panic - not syncing: panic_on_warn set ... [ 105.709836][ T9590] CPU: 0 PID: 9590 Comm: syz-executor796 Not tainted 5.6.0-rc5-syzkaller #0 [ 105.718623][ T9590] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 105.728665][ T9590] Call Trace: [ 105.731944][ T9590] dump_stack+0x188/0x20d [ 105.736256][ T9590] ? refcount_warn_saturate+0x190/0x1e0 [ 105.741790][ T9590] panic+0x2e3/0x75c [ 105.745668][ T9590] ? add_taint.cold+0x16/0x16 [ 105.750332][ T9590] ? __probe_kernel_read+0x188/0x1d0 [ 105.755626][ T9590] ? __warn.cold+0x14/0x35 [ 105.760278][ T9590] ? __warn+0xd5/0x1c8 [ 105.764346][ T9590] ? refcount_warn_saturate+0x1d1/0x1e0 [ 105.769881][ T9590] __warn.cold+0x2f/0x35 [ 105.774148][ T9590] ? refcount_warn_saturate+0x1d1/0x1e0 [ 105.779832][ T9590] report_bug+0x27b/0x2f0 [ 105.784154][ T9590] do_error_trap+0x12b/0x220 [ 105.788734][ T9590] ? refcount_warn_saturate+0x1d1/0x1e0 [ 105.794265][ T9590] do_invalid_op+0x32/0x40 [ 105.798664][ T9590] ? refcount_warn_saturate+0x1d1/0x1e0 [ 105.804224][ T9590] invalid_op+0x23/0x30 [ 105.808381][ T9590] RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 [ 105.814512][ T9590] Code: e9 db fe ff ff 48 89 df e8 9c 10 20 fe e9 8a fe ff ff e8 62 52 e3 fd 48 c7 c7 00 aa 51 88 c6 05 85 68 d2 06 01 e8 d7 62 b5 fd <0f> 0b e9 af fe ff ff 0f 1f 84 00 00 00 00 00 41 56 41 55 41 54 55 [ 105.834090][ T9590] RSP: 0018:ffffc90001ff7d28 EFLAGS: 00010282 [ 105.840131][ T9590] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 105.848794][ T9590] RDX: 0000000000000000 RSI: ffffffff815bf511 RDI: fffff520003fef97 [ 105.856783][ T9590] RBP: 0000000000000003 R08: ffff8880865dc600 R09: 0000000000000000 [ 105.864751][ T9590] R10: 0000000000000000 R11: 0000000000000000 R12: ffff888096da2040 [ 105.872707][ T9590] R13: ffff888096da2044 R14: 0000000000000281 R15: ffff88808bd311c0 [ 105.880713][ T9590] ? vprintk_func+0x81/0x17e [ 105.885293][ T9590] ? refcount_warn_saturate+0x1d1/0x1e0 [ 105.890823][ T9590] free_nsproxy+0x445/0x4a0 [ 105.895319][ T9590] switch_task_namespaces+0xaa/0xc0 [ 105.900602][ T9590] do_exit+0xb2f/0x2dd0 [ 105.904908][ T9590] ? mm_update_next_owner+0x7a0/0x7a0 [ 105.910277][ T9590] ? up_read+0x1ab/0x750 [ 105.914517][ T9590] ? mark_held_locks+0x9f/0xe0 [ 105.919280][ T9590] ? down_read_non_owner+0x470/0x470 [ 105.924554][ T9590] do_group_exit+0x125/0x340 [ 105.929136][ T9590] __ia32_sys_exit_group+0x3a/0x50 [ 105.934236][ T9590] do_fast_syscall_32+0x270/0xe8f [ 105.939247][ T9590] entry_SYSENTER_compat+0x70/0x7f [ 105.947067][ T9590] Kernel Offset: disabled [ 105.951454][ T9590] Rebooting in 86400 seconds..