[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 68.346985][ T27] audit: type=1800 audit(1584145375.329:25): pid=9354 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 68.379740][ T27] audit: type=1800 audit(1584145375.329:26): pid=9354 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 68.437583][ T27] audit: type=1800 audit(1584145375.329:27): pid=9354 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 '10.128.0.35' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 80.656780][ T9507] IPVS: ftp: loaded support on port[0] = 21 [ 80.687564][ T9507] netlink: 16 bytes leftover after parsing attributes in process `syz-executor199'. [ 80.750808][ T9507] ------------[ cut here ]------------ [ 80.756316][ T9507] refcount_t: underflow; use-after-free. [ 80.762335][ T9507] WARNING: CPU: 0 PID: 9507 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 [ 80.771688][ T9507] Kernel panic - not syncing: panic_on_warn set ... [ 80.778252][ T9507] CPU: 0 PID: 9507 Comm: syz-executor199 Not tainted 5.6.0-rc3-syzkaller #0 [ 80.787011][ T9507] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 80.797041][ T9507] Call Trace: [ 80.800313][ T9507] dump_stack+0x188/0x20d [ 80.804639][ T9507] ? refcount_warn_saturate+0xf0/0x1e0 [ 80.810518][ T9507] panic+0x2e3/0x75c [ 80.814410][ T9507] ? add_taint.cold+0x16/0x16 [ 80.819113][ T9507] ? __probe_kernel_read+0x188/0x1d0 [ 80.824377][ T9507] ? __warn.cold+0x14/0x35 [ 80.828773][ T9507] ? __warn+0xd5/0x1c8 [ 80.832826][ T9507] ? refcount_warn_saturate+0x1d1/0x1e0 [ 80.838351][ T9507] __warn.cold+0x2f/0x35 [ 80.842621][ T9507] ? refcount_warn_saturate+0x1d1/0x1e0 [ 80.848149][ T9507] report_bug+0x27b/0x2f0 [ 80.852460][ T9507] do_error_trap+0x12b/0x220 [ 80.857026][ T9507] ? refcount_warn_saturate+0x1d1/0x1e0 [ 80.862554][ T9507] do_invalid_op+0x32/0x40 [ 80.866948][ T9507] ? refcount_warn_saturate+0x1d1/0x1e0 [ 80.872472][ T9507] invalid_op+0x23/0x30 [ 80.876620][ T9507] RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 [ 80.882759][ T9507] Code: e9 db fe ff ff 48 89 df e8 ac 22 21 fe e9 8a fe ff ff e8 f2 7c e4 fd 48 c7 c7 40 a3 51 88 c6 05 b6 8c d3 06 01 e8 f7 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 [ 80.902461][ T9507] RSP: 0018:ffffc900032b7d50 EFLAGS: 00010286 [ 80.908526][ T9507] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 80.916475][ T9507] RDX: 0000000000000000 RSI: ffffffff815bf411 RDI: fffff52000656f9c [ 80.924422][ T9507] RBP: 0000000000000003 R08: ffff8880a21ee500 R09: 0000000000000000 [ 80.932372][ T9507] R10: 0000000000000000 R11: 0000000000000000 R12: ffff88808eafa040 [ 80.940319][ T9507] R13: ffff88808eafa044 R14: 0000000000000001 R15: 00000000000002aa [ 80.948297][ T9507] ? vprintk_func+0x81/0x17e [ 80.953005][ T9507] free_nsproxy+0x445/0x4a0 [ 80.957488][ T9507] switch_task_namespaces+0xaa/0xc0 [ 80.962666][ T9507] do_exit+0xb54/0x2db0 [ 80.966802][ T9507] ? mm_update_next_owner+0x7a0/0x7a0 [ 80.972166][ T9507] ? up_read+0x1ab/0x750 [ 80.976437][ T9507] ? mark_held_locks+0x9f/0xe0 [ 80.981185][ T9507] ? down_read_non_owner+0x470/0x470 [ 80.986454][ T9507] ? handle_mm_fault+0x491/0xa10 [ 80.991414][ T9507] do_group_exit+0x125/0x340 [ 80.995986][ T9507] __x64_sys_exit_group+0x3a/0x50 [ 81.001081][ T9507] do_syscall_64+0xf6/0x790 [ 81.005568][ T9507] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 81.011438][ T9507] RIP: 0033:0x43f998 [ 81.015311][ T9507] 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 [ 81.034898][ T9507] RSP: 002b:00007fff6de09218 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 81.043294][ T9507] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 000000000043f998 [ 81.051248][ T9507] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 81.059642][ T9507] RBP: 00000000004bfa10 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 81.067689][ T9507] R10: 0000000120080522 R11: 0000000000000246 R12: 0000000000000001 [ 81.075645][ T9507] R13: 00000000006d11c0 R14: 0000000000000000 R15: 0000000000000000 [ 81.085001][ T9507] Kernel Offset: disabled [ 81.089381][ T9507] Rebooting in 86400 seconds..