[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 18.888251] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 22.712866] random: sshd: uninitialized urandom read (32 bytes read) [ 23.105557] random: sshd: uninitialized urandom read (32 bytes read) [ 23.979466] random: sshd: uninitialized urandom read (32 bytes read) [ 24.140637] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.28' (ECDSA) to the list of known hosts. [ 29.615912] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program executing program executing program executing program executing program executing program [ 29.978104] ------------[ cut here ]------------ [ 29.983045] kernel BUG at fs/userfaultfd.c:883! [ 29.987801] invalid opcode: 0000 [#1] SMP KASAN [ 29.992471] CPU: 1 PID: 4534 Comm: syz-executor868 Not tainted 4.18.0-rc5+ #150 [ 29.999904] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 30.009264] RIP: 0010:userfaultfd_release+0x5fb/0x770 [ 30.014442] 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 [ 30.033583] RSP: 0018:ffff8801b04ffa80 EFLAGS: 00010293 [ 30.039031] RAX: ffff8801aee9c300 RBX: dffffc0000000000 RCX: ffffffff81db4a59 [ 30.046295] RDX: 0000000000000000 RSI: ffffffff81db4ccb RDI: 0000000000000000 [ 30.053552] RBP: ffff8801b04ffbd0 R08: ffff8801aee9c300 R09: 0000000000000000 [ 30.060836] R10: ffff8801aee9cb38 R11: 16fb0df9f74494d6 R12: ffff8801afd27670 [ 30.068190] R13: 0000000000000000 R14: ffff8801afd27568 R15: 0000000000000000 [ 30.075449] FS: 00000000019fe880(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000 [ 30.083659] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 30.089526] CR2: 00007fab3d5ede78 CR3: 00000001afc8f000 CR4: 00000000001406e0 [ 30.096784] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 30.104050] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 30.111308] Call Trace: [ 30.113911] ? userfaultfd_event_wait_completion+0xc10/0xc10 [ 30.119724] ? fsnotify_first_mark+0x350/0x350 [ 30.124303] ? __fsnotify_parent+0xcc/0x420 [ 30.128620] ? fsnotify+0x14e0/0x14e0 [ 30.132416] ? userfaultfd_event_wait_completion+0xc10/0xc10 [ 30.138339] __fput+0x355/0x8b0 [ 30.141693] ? fput+0x1a0/0x1a0 [ 30.144960] ? _raw_spin_unlock_irq+0x27/0x70 [ 30.149454] ____fput+0x15/0x20 [ 30.152731] task_work_run+0x1ec/0x2a0 [ 30.156615] ? task_work_cancel+0x250/0x250 [ 30.161013] ? exit_to_usermode_loop+0x8c/0x370 [ 30.165693] exit_to_usermode_loop+0x313/0x370 [ 30.170281] ? syscall_slow_exit_work+0x500/0x500 [ 30.175121] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 30.180648] do_syscall_64+0x6be/0x820 [ 30.184557] ? syscall_return_slowpath+0x5e0/0x5e0 [ 30.189491] ? syscall_return_slowpath+0x31d/0x5e0 [ 30.194426] ? entry_SYSCALL_64_after_hwframe+0x59/0xbe [ 30.199793] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 30.204629] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 30.209802] RIP: 0033:0x405471 [ 30.213067] 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 [ 30.232206] RSP: 002b:00007ffe1b734900 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 [ 30.239922] RAX: 0000000000000000 RBX: 0000000000000005 RCX: 0000000000405471 [ 30.247183] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005 [ 30.254453] RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000 [ 30.261811] R10: 00007ffe1b734910 R11: 0000000000000293 R12: 00000000006dbc3c [ 30.269086] R13: 00000000006dbda0 R14: 0000000000000008 R15: 0000000000000001 [ 30.276349] Modules linked in: [ 30.279570] Dumping ftrace buffer: [ 30.283095] (ftrace buffer empty) [ 30.286855] ---[ end trace 43113bc2798a8bd8 ]--- [ 30.291640] RIP: 0010:userfaultfd_release+0x5fb/0x770 [ 30.296860] 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 [ 30.316142] RSP: 0018:ffff8801b04ffa80 EFLAGS: 00010293 [ 30.321642] RAX: ffff8801aee9c300 RBX: dffffc0000000000 RCX: ffffffff81db4a59 [ 30.328958] RDX: 0000000000000000 RSI: ffffffff81db4ccb RDI: 0000000000000000 [ 30.336247] RBP: ffff8801b04ffbd0 R08: ffff8801aee9c300 R09: 0000000000000000 [ 30.343562] R10: ffff8801aee9cb38 R11: 16fb0df9f74494d6 R12: ffff8801afd27670 [ 30.350870] R13: 0000000000000000 R14: ffff8801afd27568 R15: 0000000000000000 [ 30.358157] FS: 00000000019fe880(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000 [ 30.366409] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 30.372319] CR2: 00007fab3d5ede78 CR3: 00000001afc8f000 CR4: 00000000001406e0 [ 30.379608] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 30.386913] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 30.394201] Kernel panic - not syncing: Fatal exception [ 30.400340] Dumping ftrace buffer: [ 30.403877] (ftrace buffer empty) [ 30.407589] Kernel Offset: disabled [ 30.411204] Rebooting in 86400 seconds..