[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 14.505367] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 30.010557] random: sshd: uninitialized urandom read (32 bytes read) [ 30.370320] random: sshd: uninitialized urandom read (32 bytes read) [ 30.734036] random: sshd: uninitialized urandom read (32 bytes read) [ 45.619575] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.17' (ECDSA) to the list of known hosts. [ 51.099462] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 51.299343] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 51.307587] IP: [] l2tp_session_free+0x11c/0x200 [ 51.314007] PGD 1c7589067 [ 51.316659] PUD 1c9d94067 PMD 0 [ 51.320149] [ 51.321772] Oops: 0002 [#1] PREEMPT SMP KASAN [ 51.326239] Dumping ftrace buffer: [ 51.329752] (ftrace buffer empty) [ 51.333435] Modules linked in: [ 51.336727] CPU: 1 PID: 3821 Comm: syz-executor368 Not tainted 4.9.117-g8b21e85 #71 [ 51.344491] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 51.353821] task: ffff8801b59a3000 task.stack: ffff8801d9160000 [ 51.359859] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 51.368705] RSP: 0018:ffff8801d9167ca0 EFLAGS: 00010246 [ 51.374125] RAX: dffffc0000000000 RBX: ffff8801cb3d5900 RCX: 0000000000000000 [ 51.381376] RDX: 1ffff1003948ca60 RSI: ffffffff836bf8f1 RDI: ffff8801ca465300 [ 51.388624] RBP: ffff8801d9167cc0 R08: ffff8801b59a38e8 R09: 0000000000000000 [ 51.395876] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801ca465180 [ 51.403121] R13: ffff8801cb3d5908 R14: 0000000000000000 R15: ffffffff83015be0 [ 51.410365] FS: 000000000257c880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 51.418565] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 51.424420] CR2: 0000000000000080 CR3: 00000001d954e000 CR4: 00000000001606f0 [ 51.431677] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 51.438924] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 51.446166] Stack: [ 51.448288] ffff8801d8df8000 ffff8801cb3d5900 ffff8801d8df83d0 ffff8801d8df82d8 [ 51.456285] ffff8801d9167ce8 ffffffff836c7202 ffff8801d8df8440 ffff8801d8df8000 [ 51.464287] ffffffff836c7130 ffff8801d9167d20 ffffffff83023095 ffff8801d8df8440 [ 51.472282] Call Trace: [ 51.474849] [] pppol2tp_session_destruct+0xd2/0x110 [ 51.481488] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 51.487777] [] __sk_destruct+0x55/0x590 [ 51.493383] [] ? sock_release+0x1c0/0x1c0 [ 51.499161] [] sk_destruct+0x63/0x80 [ 51.504507] [] __sk_free+0x4f/0x220 [ 51.509754] [] sk_free+0x2b/0x40 [ 51.514744] [] pppol2tp_release+0x239/0x2e0 [ 51.520685] [] sock_release+0x96/0x1c0 [ 51.526203] [] sock_close+0x16/0x20 [ 51.531462] [] __fput+0x263/0x700 [ 51.536535] [] ____fput+0x15/0x20 [ 51.541612] [] task_work_run+0x10c/0x180 [ 51.547293] [] exit_to_usermode_loop+0xfc/0x120 [ 51.553582] [] do_syscall_64+0x364/0x490 [ 51.559269] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 51.566162] 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 e5 f1 c9 fd 4c 89 ea 48 b8 00 [ 51.593159] RIP [] l2tp_session_free+0x11c/0x200 [ 51.599695] RSP [ 51.603293] CR2: 0000000000000080 [ 51.606912] ---[ end trace 562eca4d66b8ce5d ]--- [ 51.611653] Kernel panic - not syncing: Fatal exception [ 51.617326] Dumping ftrace buffer: [ 51.620837] (ftrace buffer empty) [ 51.624527] Kernel Offset: disabled [ 51.628125] Rebooting in 86400 seconds..