[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 73.482536][ T27] audit: type=1800 audit(1584124472.836:25): pid=9315 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 73.503453][ T27] audit: type=1800 audit(1584124472.836:26): pid=9315 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 73.538671][ T27] audit: type=1800 audit(1584124472.846:27): pid=9315 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: [ 82.283539][ T9470] IPVS: ftp: loaded support on port[0] = 21 [ 82.316437][ T9470] netlink: 16 bytes leftover after parsing attributes in process `syz-executor388'. [ 82.359694][ T9470] ------------[ cut here ]------------ [ 82.365205][ T9470] refcount_t: underflow; use-after-free. [ 82.371395][ T9470] WARNING: CPU: 1 PID: 9470 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 [ 82.380787][ T9470] Kernel panic - not syncing: panic_on_warn set ... [ 82.387387][ T9470] CPU: 1 PID: 9470 Comm: syz-executor388 Not tainted 5.6.0-rc3-next-20200228-syzkaller #0 [ 82.397282][ T9470] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 82.407332][ T9470] Call Trace: [ 82.410615][ T9470] dump_stack+0x188/0x20d [ 82.414934][ T9470] ? refcount_warn_saturate+0x150/0x1e0 [ 82.420468][ T9470] panic+0x2e3/0x75c [ 82.424366][ T9470] ? add_taint.cold+0x16/0x16 [ 82.429066][ T9470] ? __probe_kernel_read+0x188/0x1d0 [ 82.434363][ T9470] ? __warn.cold+0x14/0x35 [ 82.438764][ T9470] ? __warn+0xd5/0x1c8 [ 82.442821][ T9470] ? refcount_warn_saturate+0x1d1/0x1e0 [ 82.448364][ T9470] __warn.cold+0x2f/0x35 [ 82.452614][ T9470] ? refcount_warn_saturate+0x1d1/0x1e0 [ 82.458150][ T9470] report_bug+0x27b/0x2f0 [ 82.462481][ T9470] do_error_trap+0x12b/0x220 [ 82.467104][ T9470] ? refcount_warn_saturate+0x1d1/0x1e0 [ 82.472775][ T9470] do_invalid_op+0x32/0x40 [ 82.477220][ T9470] ? refcount_warn_saturate+0x1d1/0x1e0 [ 82.482765][ T9470] invalid_op+0x23/0x30 [ 82.486916][ T9470] RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 [ 82.493087][ T9470] 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 [ 82.512688][ T9470] RSP: 0018:ffffc90001ff7d38 EFLAGS: 00010286 [ 82.520132][ T9470] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 82.528109][ T9470] RDX: 0000000000000000 RSI: ffffffff815c4e91 RDI: fffff520003fef99 [ 82.536078][ T9470] RBP: 0000000000000003 R08: ffff888088fbe300 R09: 0000000000000000 [ 82.544066][ T9470] R10: 0000000000000000 R11: 0000000000000000 R12: ffff888089e6e040 [ 82.552077][ T9470] R13: ffff888089e6e044 R14: 00000000000002ab R15: ffff8880935baac0 [ 82.560061][ T9470] ? vprintk_func+0x81/0x17e [ 82.564644][ T9470] ? refcount_warn_saturate+0x1d1/0x1e0 [ 82.570177][ T9470] free_nsproxy+0x445/0x4a0 [ 82.574676][ T9470] switch_task_namespaces+0xaa/0xc0 [ 82.579866][ T9470] do_exit+0xb4e/0x2e10 [ 82.584015][ T9470] ? mm_update_next_owner+0x7a0/0x7a0 [ 82.589374][ T9470] ? up_read+0x1a8/0x750 [ 82.593600][ T9470] ? down_read_nested+0x430/0x430 [ 82.598634][ T9470] ? handle_mm_fault+0x29e/0x660 [ 82.603558][ T9470] do_group_exit+0x125/0x340 [ 82.608133][ T9470] __x64_sys_exit_group+0x3a/0x50 [ 82.613158][ T9470] do_syscall_64+0xf6/0x790 [ 82.617660][ T9470] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 82.623578][ T9470] RIP: 0033:0x43f998 [ 82.627459][ T9470] 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 [ 82.647060][ T9470] RSP: 002b:00007ffee85ac758 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 82.655469][ T9470] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 000000000043f998 [ 82.663426][ T9470] RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 [ 82.671392][ T9470] RBP: 00000000004bfa10 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 82.679347][ T9470] R10: 0000000120080522 R11: 0000000000000246 R12: 0000000000000001 [ 82.687308][ T9470] R13: 00000000006d11c0 R14: 0000000000000000 R15: 0000000000000000 [ 82.696473][ T9470] Kernel Offset: disabled [ 82.700953][ T9470] Rebooting in 86400 seconds..