[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 26.041201] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 29.590919] random: sshd: uninitialized urandom read (32 bytes read) [ 30.055501] random: sshd: uninitialized urandom read (32 bytes read) [ 31.110534] random: sshd: uninitialized urandom read (32 bytes read) [ 31.331241] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.29' (ECDSA) to the list of known hosts. [ 36.863477] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 37.401635] ------------[ cut here ]------------ [ 37.407016] kernel BUG at fs/userfaultfd.c:883! [ 37.411984] invalid opcode: 0000 [#1] SMP KASAN [ 37.416726] CPU: 0 PID: 4708 Comm: syz-executor086 Not tainted 4.18.0-rc4+ #148 [ 37.424222] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 37.433641] RIP: 0010:userfaultfd_release+0x5fb/0x770 [ 37.439107] Code: 00 31 c0 48 8b 4d d0 65 48 33 0c 25 28 00 00 00 0f 85 a1 00 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 75 be a0 ff <0f> 0b 4c 89 f7 e8 0b 9e de ff e9 11 fc ff ff 4c 89 e7 e8 5e 9d de [ 37.458332] RSP: 0018:ffff8801d8407a80 EFLAGS: 00010293 [ 37.463723] RAX: ffff8801d8742080 RBX: dffffc0000000000 RCX: ffffffff81db4a59 [ 37.471030] RDX: 0000000000000000 RSI: ffffffff81db4ccb RDI: 0000000000000000 [ 37.478316] RBP: ffff8801d8407bd0 R08: ffff8801d8742080 R09: 0000000000000000 [ 37.485593] R10: ffff8801d87428b8 R11: 16fb0df9f74494d6 R12: ffff8801d89a3b58 [ 37.492894] R13: 0000000000000000 R14: ffff8801d89a3a50 R15: 0000000000000000 [ 37.500210] FS: 0000000000ed6880(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000 [ 37.508469] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 37.514384] CR2: 00007f45c6b81e78 CR3: 00000001acb61000 CR4: 00000000001406f0 [ 37.521691] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 37.529002] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 37.536304] Call Trace: [ 37.538935] ? userfaultfd_event_wait_completion+0xc10/0xc10 [ 37.544756] ? fsnotify_first_mark+0x350/0x350 [ 37.549352] ? __fsnotify_parent+0xcc/0x420 [ 37.553701] ? fsnotify+0x14e0/0x14e0 [ 37.557547] ? userfaultfd_event_wait_completion+0xc10/0xc10 [ 37.563383] __fput+0x355/0x8b0 [ 37.566676] ? fput+0x1a0/0x1a0 [ 37.569991] ? _raw_spin_unlock_irq+0x27/0x70 [ 37.574526] ____fput+0x15/0x20 [ 37.577843] task_work_run+0x1ec/0x2a0 [ 37.581752] ? task_work_cancel+0x250/0x250 [ 37.586107] ? exit_to_usermode_loop+0x8c/0x370 [ 37.590790] exit_to_usermode_loop+0x313/0x370 [ 37.595413] ? syscall_slow_exit_work+0x500/0x500 [ 37.600310] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 37.605846] do_syscall_64+0x6be/0x820 [ 37.609808] ? syscall_return_slowpath+0x5e0/0x5e0 [ 37.614777] ? syscall_return_slowpath+0x31d/0x5e0 [ 37.619727] ? entry_SYSCALL_64_after_hwframe+0x59/0xbe [ 37.625090] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 37.629942] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 37.635121] RIP: 0033:0x405471 [ 37.638301] Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 54 17 00 00 c3 48 83 ec 08 e8 6a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 b3 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01 [ 37.657436] RSP: 002b:00007ffcad3db600 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 [ 37.665152] RAX: 0000000000000000 RBX: 0000000000000005 RCX: 0000000000405471 [ 37.672425] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005 [ 37.681069] RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000 [ 37.688325] R10: 00007ffcad3db610 R11: 0000000000000293 R12: 00000000006dbc3c [ 37.695601] R13: 00000000006dbda0 R14: 0000000000000008 R15: 0000000000000001 [ 37.702867] Modules linked in: [ 37.706048] Dumping ftrace buffer: [ 37.709568] (ftrace buffer empty) [ 37.713423] ---[ end trace 638e68cedadb8eda ]--- [ 37.718291] RIP: 0010:userfaultfd_release+0x5fb/0x770 [ 37.723602] Code: 00 31 c0 48 8b 4d d0 65 48 33 0c 25 28 00 00 00 0f 85 a1 00 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 75 be a0 ff <0f> 0b 4c 89 f7 e8 0b 9e de ff e9 11 fc ff ff 4c 89 e7 e8 5e 9d de [ 37.743039] RSP: 0018:ffff8801d8407a80 EFLAGS: 00010293 [ 37.748538] RAX: ffff8801d8742080 RBX: dffffc0000000000 RCX: ffffffff81db4a59 [ 37.756646] RDX: 0000000000000000 RSI: ffffffff81db4ccb RDI: 0000000000000000 [ 37.764409] RBP: ffff8801d8407bd0 R08: ffff8801d8742080 R09: 0000000000000000 [ 37.771826] R10: ffff8801d87428b8 R11: 16fb0df9f74494d6 R12: ffff8801d89a3b58 [ 37.779128] R13: 0000000000000000 R14: ffff8801d89a3a50 R15: 0000000000000000 [ 37.786497] FS: 0000000000ed6880(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000 [ 37.794791] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 37.800742] CR2: 00007f45c6b81e78 CR3: 00000001acb61000 CR4: 00000000001406f0 [ 37.808089] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 37.815408] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 37.822760] Kernel panic - not syncing: Fatal exception [ 37.828719] Dumping ftrace buffer: [ 37.832292] (ftrace buffer empty) [ 37.835997] Kernel Offset: disabled [ 37.839632] Rebooting in 86400 seconds..