[ 36.232315][ T27] audit: type=1800 audit(1555808645.456:27): pid=7509 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [ 36.254346][ T27] audit: type=1800 audit(1555808645.456:28): pid=7509 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="ssh" dev="sda1" ino=2417 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. [ 37.003178][ T27] audit: type=1800 audit(1555808646.286:29): pid=7509 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="rc.local" dev="sda1" ino=2432 res=0 [ 37.023015][ T27] audit: type=1800 audit(1555808646.286:30): pid=7509 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="rmnologin" dev="sda1" ino=2423 res=0 Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.0.50' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 48.051810][ T7664] ------------[ cut here ]------------ [ 48.057382][ T7664] percpu_ref_kill_and_confirm called more than once on io_ring_ctx_ref_free! [ 48.057607][ T7664] WARNING: CPU: 1 PID: 7664 at lib/percpu-refcount.c:335 percpu_ref_kill_and_confirm+0x341/0x3b0 [ 48.076890][ T7664] Kernel panic - not syncing: panic_on_warn set ... [ 48.083459][ T7664] CPU: 1 PID: 7664 Comm: syz-executor736 Not tainted 5.1.0-rc5+ #78 [ 48.091484][ T7664] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 48.101523][ T7664] Call Trace: [ 48.104797][ T7664] dump_stack+0x172/0x1f0 [ 48.109106][ T7664] ? percpu_ref_kill_and_confirm+0x340/0x3b0 [ 48.115221][ T7664] panic+0x2cb/0x65c [ 48.119104][ T7664] ? __warn_printk+0xf3/0xf3 [ 48.123731][ T7664] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 48.129706][ T7664] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 48.135986][ T7664] ? __warn.cold+0x5/0x45 [ 48.140305][ T7664] ? __warn+0xe8/0x1d0 [ 48.144372][ T7664] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 48.150344][ T7664] __warn.cold+0x20/0x45 [ 48.154568][ T7664] ? vprintk_emit+0x1ce/0x6d0 [ 48.159328][ T7664] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 48.165360][ T7664] report_bug+0x263/0x2b0 [ 48.169769][ T7664] do_error_trap+0x11b/0x200 [ 48.174342][ T7664] do_invalid_op+0x37/0x50 [ 48.178735][ T7664] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 48.184751][ T7664] invalid_op+0x14/0x20 [ 48.188902][ T7664] RIP: 0010:percpu_ref_kill_and_confirm+0x341/0x3b0 [ 48.195476][ T7664] Code: 42 e0 2a 06 01 48 89 fa 48 c1 ea 03 80 3c 02 00 75 76 49 8b 54 24 10 48 c7 c6 a0 71 a1 87 48 c7 c7 40 71 a1 87 e8 ad 92 13 fe <0f> 0b 48 b8 00 00 00 00 00 fc ff df 4c 89 ea 48 c1 ea 03 80 3c 02 [ 48.215132][ T7664] RSP: 0018:ffff888096937cf0 EFLAGS: 00010082 [ 48.221189][ T7664] RAX: 0000000000000000 RBX: 0000607f5142dde3 RCX: 0000000000000000 [ 48.229144][ T7664] RDX: 0000000000000000 RSI: ffffffff815afcf6 RDI: ffffed1012d26f90 [ 48.238063][ T7664] RBP: ffff888096937d20 R08: ffff888097b14300 R09: fffffbfff1133639 [ 48.246979][ T7664] R10: fffffbfff1133638 R11: ffffffff8899b1c3 R12: ffff88809237f580 [ 48.254934][ T7664] R13: ffff88809237f588 R14: 0000000000000286 R15: 0000000000000000 [ 48.262910][ T7664] ? vprintk_func+0x86/0x189 [ 48.267482][ T7664] __io_uring_register+0xa7/0x1fe0 [ 48.272580][ T7664] ? __mutex_lock+0x3cd/0x1310 [ 48.277336][ T7664] ? __x64_sys_io_uring_register+0x182/0x1f0 [ 48.283401][ T7664] ? mutex_trylock+0x1e0/0x1e0 [ 48.288149][ T7664] ? io_sq_wq_submit_work+0x10f0/0x10f0 [ 48.293686][ T7664] ? kasan_check_write+0x14/0x20 [ 48.298742][ T7664] __x64_sys_io_uring_register+0x193/0x1f0 [ 48.304530][ T7664] do_syscall_64+0x103/0x610 [ 48.309097][ T7664] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 48.314966][ T7664] RIP: 0033:0x446799 [ 48.318834][ T7664] Code: e8 5c b3 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 0b 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00 [ 48.338416][ T7664] RSP: 002b:00007fee7f015db8 EFLAGS: 00000246 ORIG_RAX: 00000000000001ab [ 48.346860][ T7664] RAX: ffffffffffffffda RBX: 00000000006dbc38 RCX: 0000000000446799 [ 48.354823][ T7664] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 [ 48.362895][ T7664] RBP: 00000000006dbc30 R08: 00007fee7f016700 R09: 0000000000000000 [ 48.370845][ T7664] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc3c [ 48.378810][ T7664] R13: 00007fff0720c4df R14: 00007fee7f0169c0 R15: 20c49ba5e353f7cf [ 48.387969][ T7664] Kernel Offset: disabled [ 48.392351][ T7664] Rebooting in 86400 seconds..