[ 40.864859][ T27] audit: type=1800 audit(1555813881.544:27): pid=7740 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [ 40.904713][ T27] audit: type=1800 audit(1555813881.604:28): pid=7740 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. [ 41.509720][ T27] audit: type=1800 audit(1555813882.214:29): pid=7740 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="rc.local" dev="sda1" ino=2432 res=0 [ 41.539695][ T27] audit: type=1800 audit(1555813882.214:30): pid=7740 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 '10.128.0.31' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 49.062531][ T7893] ------------[ cut here ]------------ [ 49.068216][ T7893] percpu_ref_kill_and_confirm called more than once on io_ring_ctx_ref_free! [ 49.068426][ T7893] WARNING: CPU: 0 PID: 7893 at lib/percpu-refcount.c:335 percpu_ref_kill_and_confirm+0x341/0x3b0 [ 49.087726][ T7893] Kernel panic - not syncing: panic_on_warn set ... [ 49.094293][ T7893] CPU: 0 PID: 7893 Comm: syz-executor158 Not tainted 5.1.0-rc5+ #78 [ 49.102246][ T7893] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 49.112284][ T7893] Call Trace: [ 49.115564][ T7893] dump_stack+0x172/0x1f0 [ 49.119902][ T7893] ? percpu_ref_kill_and_confirm+0x340/0x3b0 [ 49.125864][ T7893] panic+0x2cb/0x65c [ 49.129744][ T7893] ? __warn_printk+0xf3/0xf3 [ 49.134341][ T7893] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 49.140314][ T7893] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 49.146547][ T7893] ? __warn.cold+0x5/0x45 [ 49.150860][ T7893] ? __warn+0xe8/0x1d0 [ 49.154938][ T7893] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 49.160921][ T7893] __warn.cold+0x20/0x45 [ 49.165145][ T7893] ? vprintk_emit+0x1ce/0x6d0 [ 49.170593][ T7893] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 49.176569][ T7893] report_bug+0x263/0x2b0 [ 49.180900][ T7893] do_error_trap+0x11b/0x200 [ 49.185475][ T7893] do_invalid_op+0x37/0x50 [ 49.189882][ T7893] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 49.195844][ T7893] invalid_op+0x14/0x20 [ 49.199988][ T7893] RIP: 0010:percpu_ref_kill_and_confirm+0x341/0x3b0 [ 49.206556][ T7893] 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 [ 49.226314][ T7893] RSP: 0018:ffff88808527fcf0 EFLAGS: 00010082 [ 49.232365][ T7893] RAX: 0000000000000000 RBX: 0000607f5142eb8b RCX: 0000000000000000 [ 49.240331][ T7893] RDX: 0000000000000000 RSI: ffffffff815afcf6 RDI: ffffed1010a4ff90 [ 49.248284][ T7893] RBP: ffff88808527fd20 R08: ffff88809490a6c0 R09: fffffbfff1133639 [ 49.256232][ T7893] R10: fffffbfff1133638 R11: ffffffff8899b1c3 R12: ffff8880a5368bc0 [ 49.264181][ T7893] R13: ffff8880a5368bc8 R14: 0000000000000286 R15: 0000000000000000 [ 49.272151][ T7893] ? vprintk_func+0x86/0x189 [ 49.276727][ T7893] __io_uring_register+0xa7/0x1fe0 [ 49.281818][ T7893] ? __mutex_lock+0x3cd/0x1310 [ 49.286559][ T7893] ? __x64_sys_io_uring_register+0x182/0x1f0 [ 49.292522][ T7893] ? mutex_trylock+0x1e0/0x1e0 [ 49.297271][ T7893] ? io_sq_wq_submit_work+0x10f0/0x10f0 [ 49.302812][ T7893] ? kasan_check_write+0x14/0x20 [ 49.307756][ T7893] __x64_sys_io_uring_register+0x193/0x1f0 [ 49.313543][ T7893] do_syscall_64+0x103/0x610 [ 49.318119][ T7893] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 49.323986][ T7893] RIP: 0033:0x4467c9 [ 49.327861][ T7893] 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 [ 49.347474][ T7893] RSP: 002b:00007f92d34f1db8 EFLAGS: 00000246 ORIG_RAX: 00000000000001ab [ 49.355864][ T7893] RAX: ffffffffffffffda RBX: 00000000006dbc38 RCX: 00000000004467c9 [ 49.363812][ T7893] RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000003 [ 49.371782][ T7893] RBP: 00000000006dbc30 R08: 00007f92d34f2700 R09: 0000000000000000 [ 49.379733][ T7893] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc3c [ 49.387684][ T7893] R13: 00007fffd7e18e5f R14: 00007f92d34f29c0 R15: 20c49ba5e353f7cf [ 49.396527][ T7893] Kernel Offset: disabled [ 49.400912][ T7893] Rebooting in 86400 seconds..