[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 77.961133][ T27] audit: type=1800 audit(1584196903.821:25): pid=9173 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 77.981915][ T27] audit: type=1800 audit(1584196903.821:26): pid=9173 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 78.002898][ T27] audit: type=1800 audit(1584196903.831:27): pid=9173 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 '10.128.1.29' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 88.757321][ T9327] IPVS: ftp: loaded support on port[0] = 21 [ 88.788262][ T9327] netlink: 16 bytes leftover after parsing attributes in process `syz-executor264'. [ 88.886998][ T9327] ------------[ cut here ]------------ [ 88.892505][ T9327] refcount_t: underflow; use-after-free. [ 88.898510][ T9327] WARNING: CPU: 0 PID: 9327 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 [ 88.907876][ T9327] Kernel panic - not syncing: panic_on_warn set ... [ 88.914458][ T9327] CPU: 0 PID: 9327 Comm: syz-executor264 Not tainted 5.6.0-rc5-syzkaller #0 [ 88.923102][ T9327] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 88.933149][ T9327] Call Trace: [ 88.936422][ T9327] dump_stack+0x188/0x20d [ 88.940974][ T9327] ? refcount_warn_saturate+0x1b0/0x1e0 [ 88.947291][ T9327] panic+0x2e3/0x75c [ 88.951207][ T9327] ? add_taint.cold+0x16/0x16 [ 88.955881][ T9327] ? __probe_kernel_read+0x188/0x1d0 [ 88.961149][ T9327] ? __warn.cold+0x14/0x35 [ 88.965654][ T9327] ? __warn+0xd5/0x1c8 [ 88.969717][ T9327] ? refcount_warn_saturate+0x1d1/0x1e0 [ 88.975242][ T9327] __warn.cold+0x2f/0x35 [ 88.979483][ T9327] ? refcount_warn_saturate+0x1d1/0x1e0 [ 88.985193][ T9327] report_bug+0x27b/0x2f0 [ 88.989531][ T9327] do_error_trap+0x12b/0x220 [ 88.994616][ T9327] ? refcount_warn_saturate+0x1d1/0x1e0 [ 89.000164][ T9327] do_invalid_op+0x32/0x40 [ 89.004571][ T9327] ? refcount_warn_saturate+0x1d1/0x1e0 [ 89.010390][ T9327] invalid_op+0x23/0x30 [ 89.014569][ T9327] RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 [ 89.020715][ T9327] Code: e9 db fe ff ff 48 89 df e8 7c 04 20 fe e9 8a fe ff ff e8 b2 46 e3 fd 48 c7 c7 c0 ab 51 88 c6 05 c8 8d d2 06 01 e8 f7 56 b5 fd <0f> 0b e9 af fe ff ff 0f 1f 84 00 00 00 00 00 41 56 41 55 41 54 55 [ 89.040919][ T9327] RSP: 0018:ffffc90002067d38 EFLAGS: 00010286 [ 89.047005][ T9327] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 89.055053][ T9327] RDX: 0000000000000000 RSI: ffffffff815bf511 RDI: fffff5200040cf99 [ 89.063007][ T9327] RBP: 0000000000000003 R08: ffff8880a432c200 R09: 0000000000000000 [ 89.071042][ T9327] R10: 0000000000000000 R11: 0000000000000000 R12: ffff88808f0f6040 [ 89.079200][ T9327] R13: ffff88808f0f6044 R14: 00000000000002ab R15: ffff888089b5a080 [ 89.087261][ T9327] ? vprintk_func+0x81/0x17e [ 89.091874][ T9327] ? refcount_warn_saturate+0x1d1/0x1e0 [ 89.097416][ T9327] free_nsproxy+0x445/0x4a0 [ 89.101910][ T9327] switch_task_namespaces+0xaa/0xc0 [ 89.107150][ T9327] do_exit+0xb2f/0x2dd0 [ 89.111730][ T9327] ? mm_update_next_owner+0x7a0/0x7a0 [ 89.117458][ T9327] ? up_read+0x1ab/0x750 [ 89.121695][ T9327] ? mark_held_locks+0x9f/0xe0 [ 89.126450][ T9327] ? down_read_non_owner+0x470/0x470 [ 89.132046][ T9327] ? handle_mm_fault+0x491/0xa10 [ 89.136972][ T9327] do_group_exit+0x125/0x340 [ 89.141551][ T9327] __x64_sys_exit_group+0x3a/0x50 [ 89.146647][ T9327] do_syscall_64+0xf6/0x7d0 [ 89.151136][ T9327] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 89.157011][ T9327] RIP: 0033:0x43f998 [ 89.165415][ T9327] 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 [ 89.185020][ T9327] RSP: 002b:00007ffddd1be678 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 89.193411][ T9327] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 000000000043f998 [ 89.201383][ T9327] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 89.209644][ T9327] RBP: 00000000004bfa10 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 89.217674][ T9327] R10: 0000000120080522 R11: 0000000000000246 R12: 0000000000000001 [ 89.225741][ T9327] R13: 00000000006d11c0 R14: 0000000000000000 R15: 0000000000000000 [ 89.235547][ T9327] Kernel Offset: disabled [ 89.239963][ T9327] Rebooting in 86400 seconds..