[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.818660] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 19.256078] random: sshd: uninitialized urandom read (32 bytes read) [ 19.585125] random: sshd: uninitialized urandom read (32 bytes read) [ 20.336671] random: sshd: uninitialized urandom read (32 bytes read) [ 20.472768] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.45' (ECDSA) to the list of known hosts. [ 25.942593] 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 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 28.003245] ------------[ cut here ]------------ [ 28.008025] kernel BUG at fs/userfaultfd.c:883! [ 28.012743] invalid opcode: 0000 [#1] SMP KASAN [ 28.017436] CPU: 1 PID: 4678 Comm: syz-executor270 Not tainted 4.18.0-rc5-next-20180718+ #10 [ 28.025990] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.035335] RIP: 0010:userfaultfd_release+0x6f6/0x8d0 [ 28.040500] Code: 00 31 c0 48 8b 4d d0 65 48 33 0c 25 28 00 00 00 0f 85 eb 00 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 fa ff 9e ff <0f> 0b e8 f3 ff 9e ff 48 8b bd 80 fe ff ff e8 b7 6b 80 ff 48 8b bd [ 28.059618] RSP: 0018:ffff8801abe57a40 EFLAGS: 00010293 [ 28.064965] RAX: ffff8801d9766200 RBX: dffffc0000000000 RCX: ffffffff81dda41e [ 28.072215] RDX: 0000000000000000 RSI: ffffffff81dda686 RDI: 0000000000000000 [ 28.079467] RBP: ffff8801abe57bd0 R08: ffff8801d9766200 R09: ffff8801b0da3ae0 [ 28.086716] R10: ffffed00357caf55 R11: 0000000000000003 R12: ffff8801d9667da8 [ 28.093990] R13: 0000000000000000 R14: ffff8801d9667ca0 R15: 0000000000020300 [ 28.101245] FS: 0000000001810880(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000 [ 28.109453] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 28.115324] CR2: 00007fee25399e78 CR3: 00000001d2c6c000 CR4: 00000000001406e0 [ 28.122586] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 28.129837] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 28.137084] Call Trace: [ 28.139675] ? userfaultfd_ctx_get+0x2f0/0x2f0 [ 28.144258] ? locks_remove_file+0x402/0x5c0 [ 28.148647] ? fcntl_setlk+0x1040/0x1040 [ 28.152691] ? blkcg_maybe_throttle_current+0xa1b/0x1040 [ 28.158123] ? fsnotify_first_mark+0x350/0x350 [ 28.162690] ? __fsnotify_parent+0xcc/0x420 [ 28.167012] ? fsnotify+0x14e0/0x14e0 [ 28.170799] ? userfaultfd_ctx_get+0x2f0/0x2f0 [ 28.175363] __fput+0x37c/0x8a0 [ 28.178627] ? fput+0x1a0/0x1a0 [ 28.181900] ? kasan_check_write+0x14/0x20 [ 28.186125] ? do_raw_spin_lock+0xc1/0x200 [ 28.190347] ____fput+0x15/0x20 [ 28.193615] task_work_run+0x1ec/0x2a0 [ 28.197574] ? task_work_cancel+0x250/0x250 [ 28.201887] ? clock_was_set_work+0x30/0x30 [ 28.206190] ? copy_fd_bitmaps+0x210/0x210 [ 28.210417] exit_to_usermode_loop+0x318/0x380 [ 28.214981] ? syscall_slow_exit_work+0x500/0x500 [ 28.219819] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 28.225343] do_syscall_64+0x6be/0x820 [ 28.229223] ? syscall_return_slowpath+0x5e0/0x5e0 [ 28.234152] ? syscall_return_slowpath+0x31d/0x5e0 [ 28.239075] ? prepare_exit_to_usermode+0x3b0/0x3b0 [ 28.244076] ? prepare_exit_to_usermode+0x291/0x3b0 [ 28.249074] ? perf_trace_sys_enter+0xb10/0xb10 [ 28.253722] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 28.258550] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 28.263717] RIP: 0033:0x405471 [ 28.266904] 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 [ 28.286036] RSP: 002b:00007ffc0b2c22b0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 [ 28.293734] RAX: 0000000000000000 RBX: 0000000000000005 RCX: 0000000000405471 [ 28.300988] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005 [ 28.308248] RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000 [ 28.315520] R10: 00007ffc0b2c22c0 R11: 0000000000000293 R12: 00000000006dbc3c [ 28.322782] R13: 00000000006dbda0 R14: 0000000000000008 R15: 0000000000000001 [ 28.330035] Modules linked in: [ 28.333218] Dumping ftrace buffer: [ 28.336740] (ftrace buffer empty) [ 28.340698] ---[ end trace 4e3645ab103a16c7 ]--- [ 28.345480] RIP: 0010:userfaultfd_release+0x6f6/0x8d0 [ 28.350694] Code: 00 31 c0 48 8b 4d d0 65 48 33 0c 25 28 00 00 00 0f 85 eb 00 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 fa ff 9e ff <0f> 0b e8 f3 ff 9e ff 48 8b bd 80 fe ff ff e8 b7 6b 80 ff 48 8b bd [ 28.369937] RSP: 0018:ffff8801abe57a40 EFLAGS: 00010293 [ 28.375319] RAX: ffff8801d9766200 RBX: dffffc0000000000 RCX: ffffffff81dda41e [ 28.382598] RDX: 0000000000000000 RSI: ffffffff81dda686 RDI: 0000000000000000 [ 28.389881] RBP: ffff8801abe57bd0 R08: ffff8801d9766200 R09: ffff8801b0da3ae0 [ 28.397159] R10: ffffed00357caf55 R11: 0000000000000003 R12: ffff8801d9667da8 [ 28.404437] R13: 0000000000000000 R14: ffff8801d9667ca0 R15: 0000000000020300 [ 28.411728] FS: 0000000001810880(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000 [ 28.419962] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 28.425849] CR2: 00007fee25399e78 CR3: 00000001d2c6c000 CR4: 00000000001406e0 [ 28.433134] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 28.440409] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 28.447700] Kernel panic - not syncing: Fatal exception [ 28.453781] Dumping ftrace buffer: [ 28.457304] (ftrace buffer empty) [ 28.460991] Kernel Offset: disabled [ 28.464595] Rebooting in 86400 seconds..