[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c.
[....] Starting OpenBSD Secure Shell server: sshd[   21.134394] random: sshd: uninitialized urandom read (32 bytes read, 34 bits of entropy available)
[?25l[?1c7[ ok 8[?25h[?0c.

Debian GNU/Linux 7 syzkaller ttyS0

syzkaller login: [   26.473542] random: sshd: uninitialized urandom read (32 bytes read, 40 bits of entropy available)
[   27.020085] random: sshd: uninitialized urandom read (32 bytes read, 40 bits of entropy available)
[   27.811281] random: sshd: uninitialized urandom read (32 bytes read, 78 bits of entropy available)
[   27.994359] random: sshd: uninitialized urandom read (32 bytes read, 81 bits of entropy available)
Warning: Permanently added '10.128.10.44' (ECDSA) to the list of known hosts.
[   33.634014] random: sshd: uninitialized urandom read (32 bytes read, 88 bits of entropy available)
executing program
executing program
[   33.821928] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080
[   33.830157] IP: [<ffffffff835a59bc>] l2tp_session_free+0x11c/0x200
[   33.836582] PGD bb132067 PUD b481f067 PMD 0 
[   33.841313] Oops: 0002 [#1] PREEMPT SMP KASAN
[   33.846258] Dumping ftrace buffer:
[   33.849768]    (ftrace buffer empty)
[   33.853454] Modules linked in:
[   33.856742] CPU: 0 PID: 212 Comm: kworker/0:1 Not tainted 4.4.150-g5541782 #19
[   33.864070] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
[   33.873404] Workqueue: sock_diag_events sock_diag_broadcast_destroy_work
[   33.880348] task: ffff8800bb0dc800 task.stack: ffff8801d9000000
[   33.886391] RIP: 0010:[<ffffffff835a59bc>]  [<ffffffff835a59bc>] l2tp_session_free+0x11c/0x200
[   33.895239] RSP: 0018:ffff8801d9007b28  EFLAGS: 00010246
[   33.900672] RAX: dffffc0000000000 RBX: ffff8801d9a1c000 RCX: 0000000000000000
[   33.907947] RDX: 1ffff10039237700 RSI: ffffffff835a5991 RDI: ffff8801c91bb800
[   33.915197] RBP: ffff8801d9007b48 R08: ffff8800bb0dd128 R09: 0000000000000000
[   33.922438] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c91bb680
[   33.929679] R13: ffff8801d9a1c008 R14: 0000000000000000 R15: ffff8801c91bb6d8
[   33.936930] FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
[   33.945127] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   33.950982] CR2: 0000000000000080 CR3: 00000000b668d000 CR4: 00000000001606f0
[   33.958225] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   33.965469] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[   33.972713] Stack:
[   33.974835]  ffff8801d9a1c0a8 dffffc0000000000 ffff8801d9a1c000 ffffffff835af470
[   33.982810]  ffff8801d9007ba0 ffffffff835a7dc9 ffff8801c91bb758 ffffed00392376db
[   33.990859]  ffff8801c91bb6d8 ffff8801c91bb6a0 ffff8801c91bb680 ffff8801c9018640
[   33.998856] Call Trace:
[   34.001419]  [<ffffffff835af470>] ? pppol2tp_session_destruct+0x110/0x110
[   34.008322]  [<ffffffff835a7dc9>] l2tp_tunnel_closeall+0x2b9/0x350
[   34.014612]  [<ffffffff835a85b2>] l2tp_tunnel_destruct+0x2f2/0x590
[   34.020905]  [<ffffffff835a846a>] ? l2tp_tunnel_destruct+0x1aa/0x590
[   34.027369]  [<ffffffff835a82c0>] ? l2tp_tunnel_del_work+0x460/0x460
[   34.033851]  [<ffffffff82f36e3c>] sk_destruct+0x4c/0x4c0
[   34.039277]  [<ffffffff82fd3f2a>] sock_diag_broadcast_destroy_work+0x21a/0x390
[   34.046625]  [<ffffffff81184eff>] process_one_work+0x7df/0x1600
[   34.052653]  [<ffffffff81184e1a>] ? process_one_work+0x6fa/0x1600
[   34.058857]  [<ffffffff81184720>] ? cancel_delayed_work_sync+0x20/0x20
[   34.065495]  [<ffffffff81185df9>] worker_thread+0xd9/0xfc0
[   34.071308]  [<ffffffff838ca65a>] ? _raw_spin_unlock_irqrestore+0x5a/0x70
[   34.078209]  [<ffffffff81193908>] kthread+0x268/0x300
[   34.083371]  [<ffffffff81185d20>] ? process_one_work+0x1600/0x1600
[   34.089660]  [<ffffffff811936a0>] ? kthread_create_on_node+0x400/0x400
[   34.096300]  [<ffffffff838bb8b0>] ? __schedule+0x7a0/0x1d70
[   34.101983]  [<ffffffff811936a0>] ? kthread_create_on_node+0x400/0x400
[   34.108620]  [<ffffffff838cb4d5>] ret_from_fork+0x55/0x80
[   34.114145]  [<ffffffff811936a0>] ? kthread_create_on_node+0x400/0x400
[   34.120780] 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 d0 00 00 00 4d 8b b4 24 80 01 00 00 <f0> 41 ff 8e 80 00 00 00 74 64 e8 15 eb da fd e8 10 eb da fd 4c 
[   34.147560] RIP  [<ffffffff835a59bc>] l2tp_session_free+0x11c/0x200
[   34.154057]  RSP <ffff8801d9007b28>
[   34.157653] CR2: 0000000000000080
[   34.161077] ---[ end trace 5347d09838687f17 ]---
[   34.165803] Kernel panic - not syncing: Fatal exception
[   34.171462] Dumping ftrace buffer:
[   34.174983]    (ftrace buffer empty)
[   34.178664] Kernel Offset: disabled
[   34.182262] Rebooting in 86400 seconds..