[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.250811] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 21.426168] random: sshd: uninitialized urandom read (32 bytes read) [ 21.939012] random: sshd: uninitialized urandom read (32 bytes read) [ 22.385054] random: sshd: uninitialized urandom read (32 bytes read) [ 22.540803] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.53' (ECDSA) to the list of known hosts. [ 27.988537] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 28.179389] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 28.187638] IP: [] l2tp_session_free+0x11c/0x200 [ 28.194073] PGD 1b848a067 [ 28.196725] PUD 1c716a067 PMD 0 [ 28.200206] [ 28.201825] Oops: 0002 [#1] PREEMPT SMP KASAN [ 28.206302] Dumping ftrace buffer: [ 28.210007] (ftrace buffer empty) [ 28.213695] Modules linked in: [ 28.216990] CPU: 0 PID: 3805 Comm: syz-executor324 Not tainted 4.9.117-g8b21e85 #71 [ 28.224771] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.234272] task: ffff8801b6a48000 task.stack: ffff8801b6370000 [ 28.240299] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 28.249159] RSP: 0018:ffff8801b6377ca0 EFLAGS: 00010246 [ 28.254595] RAX: dffffc0000000000 RBX: ffff8801ca68b680 RCX: 0000000000000000 [ 28.261926] RDX: 1ffff10036eb6d70 RSI: ffffffff836bf8f1 RDI: ffff8801b75b6b80 [ 28.269182] RBP: ffff8801b6377cc0 R08: ffff8801b6a488e8 R09: 0000000000000000 [ 28.276490] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b75b6a00 [ 28.283748] R13: ffff8801ca68b688 R14: 0000000000000000 R15: ffffffff83015be0 [ 28.290995] FS: 0000000000c99880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 28.299197] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 28.305055] CR2: 0000000000000080 CR3: 00000001b96d2000 CR4: 00000000001606f0 [ 28.312306] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 28.319572] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 28.326839] Stack: [ 28.328966] ffff8801b708dd80 ffff8801ca68b680 ffff8801b708e150 ffff8801b708e058 [ 28.336978] ffff8801b6377ce8 ffffffff836c7202 ffff8801b708e1c0 ffff8801b708dd80 [ 28.344987] ffffffff836c7130 ffff8801b6377d20 ffffffff83023095 ffff8801b708e1c0 [ 28.352999] Call Trace: [ 28.355571] [] pppol2tp_session_destruct+0xd2/0x110 [ 28.362213] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 28.368612] [] __sk_destruct+0x55/0x590 [ 28.374212] [] ? sock_release+0x1c0/0x1c0 [ 28.379981] [] sk_destruct+0x63/0x80 [ 28.385318] [] __sk_free+0x4f/0x220 [ 28.390567] [] sk_free+0x2b/0x40 [ 28.395556] [] pppol2tp_release+0x239/0x2e0 [ 28.401816] [] sock_release+0x96/0x1c0 [ 28.407351] [] sock_close+0x16/0x20 [ 28.412613] [] __fput+0x263/0x700 [ 28.417695] [] ____fput+0x15/0x20 [ 28.422777] [] task_work_run+0x10c/0x180 [ 28.428466] [] exit_to_usermode_loop+0xfc/0x120 [ 28.434776] [] do_syscall_64+0x364/0x490 [ 28.440483] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 28.447379] 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 [ 28.474314] RIP [] l2tp_session_free+0x11c/0x200 [ 28.480821] RSP [ 28.484421] CR2: 0000000000000080 [ 28.487954] ---[ end trace e2f7c4cb3477eafa ]--- [ 28.492714] Kernel panic - not syncing: Fatal exception [ 28.498556] Dumping ftrace buffer: [ 28.502081] (ftrace buffer empty) [ 28.505768] Kernel Offset: disabled [ 28.509370] Rebooting in 86400 seconds..