[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.521829] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 13.893789] random: sshd: uninitialized urandom read (32 bytes read) [ 14.429944] random: sshd: uninitialized urandom read (32 bytes read) [ 14.850551] random: sshd: uninitialized urandom read (32 bytes read) [ 18.373184] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.3' (ECDSA) to the list of known hosts. [ 23.782795] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 23.992343] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 24.000617] IP: [] l2tp_session_free+0x11c/0x200 [ 24.007028] PGD 1c4448067 [ 24.009667] PUD 1bb7ba067 PMD 0 [ 24.013136] [ 24.014751] Oops: 0002 [#1] PREEMPT SMP KASAN [ 24.019228] Dumping ftrace buffer: [ 24.022734] (ftrace buffer empty) [ 24.026422] Modules linked in: [ 24.029702] CPU: 0 PID: 3808 Comm: syz-executor068 Not tainted 4.9.117-g8b21e85 #19 [ 24.037470] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 24.046795] task: ffff8801b9e40000 task.stack: ffff8801b69d8000 [ 24.052821] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 24.061659] RSP: 0018:ffff8801b69dfca0 EFLAGS: 00010246 [ 24.067086] RAX: dffffc0000000000 RBX: ffff8801b78d9180 RCX: 0000000000000000 [ 24.074328] RDX: 1ffff100370e4b50 RSI: ffffffff836bf8f1 RDI: ffff8801b8725a80 [ 24.081575] RBP: ffff8801b69dfcc0 R08: ffff8801b9e408e8 R09: 0000000000000000 [ 24.088815] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b8725900 [ 24.096058] R13: ffff8801b78d9188 R14: 0000000000000000 R15: ffffffff83015be0 [ 24.103299] FS: 0000000001854880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 24.111493] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 24.117343] CR2: 0000000000000080 CR3: 00000001c2564000 CR4: 00000000001606f0 [ 24.124584] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 24.131823] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 24.139063] Stack: [ 24.141184] ffff8801b6463300 ffff8801b78d9180 ffff8801b64636d0 ffff8801b64635d8 [ 24.149157] ffff8801b69dfce8 ffffffff836c7202 ffff8801b6463740 ffff8801b6463300 [ 24.157130] ffffffff836c7130 ffff8801b69dfd20 ffffffff83023095 ffff8801b6463740 [ 24.165099] Call Trace: [ 24.167658] [] pppol2tp_session_destruct+0xd2/0x110 [ 24.174296] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 24.180588] [] __sk_destruct+0x55/0x590 [ 24.186183] [] ? sock_release+0x1c0/0x1c0 [ 24.191958] [] sk_destruct+0x63/0x80 [ 24.197292] [] __sk_free+0x4f/0x220 [ 24.202537] [] sk_free+0x2b/0x40 [ 24.207523] [] pppol2tp_release+0x239/0x2e0 [ 24.213474] [] sock_release+0x96/0x1c0 [ 24.218986] [] sock_close+0x16/0x20 [ 24.224231] [] __fput+0x263/0x700 [ 24.229302] [] ____fput+0x15/0x20 [ 24.234376] [] task_work_run+0x10c/0x180 [ 24.240055] [] exit_to_usermode_loop+0xfc/0x120 [ 24.246342] [] do_syscall_64+0x364/0x490 [ 24.252024] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 24.259091] 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 [ 24.285793] RIP [] l2tp_session_free+0x11c/0x200 [ 24.292288] RSP [ 24.295882] CR2: 0000000000000080 [ 24.300158] ---[ end trace 7a38b848bcc107ef ]--- [ 24.305248] Kernel panic - not syncing: Fatal exception [ 24.311100] Dumping ftrace buffer: [ 24.314634] (ftrace buffer empty) [ 24.318319] Kernel Offset: disabled [ 24.321920] Rebooting in 86400 seconds..