[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.934973] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 13.110387] random: sshd: uninitialized urandom read (32 bytes read) [ 13.249946] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 14.413229] random: sshd: uninitialized urandom read (32 bytes read) [ 22.616690] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.8' (ECDSA) to the list of known hosts. [ 28.053026] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 28.264838] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 28.273059] IP: [] l2tp_session_free+0x11c/0x200 [ 28.279474] PGD 1baf66067 [ 28.282120] PUD 1badbb067 PMD 0 [ 28.285606] [ 28.287225] Oops: 0002 [#1] PREEMPT SMP KASAN [ 28.291693] Dumping ftrace buffer: [ 28.295202] (ftrace buffer empty) [ 28.298883] Modules linked in: [ 28.302178] CPU: 1 PID: 3803 Comm: syz-executor542 Not tainted 4.9.113-g47bbcd6 #10 [ 28.309945] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.319280] task: ffff8801b5890000 task.stack: ffff8801da3b8000 [ 28.325307] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 28.334150] RSP: 0018:ffff8801da3bfca0 EFLAGS: 00010246 [ 28.339568] RAX: dffffc0000000000 RBX: ffff8801b5f92280 RCX: 0000000000000000 [ 28.346812] RDX: 1ffff100393f9fa0 RSI: ffffffff836bcce1 RDI: ffff8801c9fcfd00 [ 28.354054] RBP: ffff8801da3bfcc0 R08: ffff8801b58908e8 R09: 0000000000000000 [ 28.361297] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c9fcfb80 [ 28.368540] R13: ffff8801b5f92288 R14: 0000000000000000 R15: ffffffff83013be0 [ 28.375783] FS: 0000000001442880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 28.383985] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 28.389840] CR2: 0000000000000080 CR3: 00000001d9558000 CR4: 00000000001606f0 [ 28.397268] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 28.404521] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 28.411765] Stack: [ 28.413885] ffff8801c5225500 ffff8801b5f92280 ffff8801c52258d0 ffff8801c52257d8 [ 28.421859] ffff8801da3bfce8 ffffffff836c45f2 ffff8801c5225940 ffff8801c5225500 [ 28.429839] ffffffff836c4520 ffff8801da3bfd20 ffffffff83021095 ffff8801c5225940 [ 28.437815] Call Trace: [ 28.440376] [] pppol2tp_session_destruct+0xd2/0x110 [ 28.447013] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 28.453303] [] __sk_destruct+0x55/0x590 [ 28.458900] [] ? sock_release+0x1c0/0x1c0 [ 28.464667] [] sk_destruct+0x63/0x80 [ 28.470002] [] __sk_free+0x4f/0x220 [ 28.475250] [] sk_free+0x2b/0x40 [ 28.480233] [] pppol2tp_release+0x239/0x2e0 [ 28.486174] [] sock_release+0x96/0x1c0 [ 28.491682] [] sock_close+0x16/0x20 [ 28.496927] [] __fput+0x263/0x700 [ 28.502004] [] ____fput+0x15/0x20 [ 28.507083] [] task_work_run+0x10c/0x180 [ 28.512772] [] exit_to_usermode_loop+0xfc/0x120 [ 28.519060] [] do_syscall_64+0x364/0x490 [ 28.524745] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 28.531637] Code: 49 8d bc 24 80 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 c6 00 00 00 4d 8b b4 24 80 01 00 00 41 ff 8e 80 00 00 00 74 69 e8 55 1d ca fd 4c 89 ea 48 b8 00 [ 28.558316] RIP [] l2tp_session_free+0x11c/0x200 [ 28.564814] RSP [ 28.568415] CR2: 0000000000000080 [ 28.572296] ---[ end trace eebcf70716cdf065 ]--- [ 28.577044] Kernel panic - not syncing: Fatal exception [ 28.582766] Dumping ftrace buffer: [ 28.586276] (ftrace buffer empty) [ 28.589957] Kernel Offset: disabled [ 28.593553] Rebooting in 86400 seconds..