[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.644894] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 19.940490] random: sshd: uninitialized urandom read (32 bytes read) [ 20.516437] random: sshd: uninitialized urandom read (32 bytes read) [ 20.959765] random: sshd: uninitialized urandom read (32 bytes read) [ 21.093437] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.0' (ECDSA) to the list of known hosts. [ 26.510812] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 26.704762] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 26.712994] IP: [] l2tp_session_free+0x11c/0x200 [ 26.719416] PGD 1c9f36067 [ 26.722056] PUD 1cb2ab067 PMD 0 [ 26.725538] [ 26.727156] Oops: 0002 [#1] PREEMPT SMP KASAN [ 26.731622] Dumping ftrace buffer: [ 26.735133] (ftrace buffer empty) [ 26.738816] Modules linked in: [ 26.742099] CPU: 1 PID: 3798 Comm: syz-executor850 Not tainted 4.9.117-g8b21e85 #19 [ 26.749875] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 26.759202] task: ffff8801b7028000 task.stack: ffff8801d9878000 [ 26.765230] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 26.774072] RSP: 0018:ffff8801d987fca0 EFLAGS: 00010246 [ 26.779498] RAX: dffffc0000000000 RBX: ffff8801b8138280 RCX: 0000000000000000 [ 26.786742] RDX: 1ffff10036e22eb0 RSI: ffffffff836bf8f1 RDI: ffff8801b7117580 [ 26.793991] RBP: ffff8801d987fcc0 R08: ffff8801b70288e8 R09: 0000000000000000 [ 26.801236] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b7117400 [ 26.808478] R13: ffff8801b8138288 R14: 0000000000000000 R15: ffffffff83015be0 [ 26.815723] FS: 0000000000f1d880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 26.823923] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 26.829776] CR2: 0000000000000080 CR3: 00000001c4c25000 CR4: 00000000001606f0 [ 26.837023] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 26.844264] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 26.851505] Stack: [ 26.853627] ffff8801d9888880 ffff8801b8138280 ffff8801d9888c50 ffff8801d9888b58 [ 26.861624] ffff8801d987fce8 ffffffff836c7202 ffff8801d9888cc0 ffff8801d9888880 [ 26.869632] ffffffff836c7130 ffff8801d987fd20 ffffffff83023095 ffff8801d9888cc0 [ 26.877615] Call Trace: [ 26.880186] [] pppol2tp_session_destruct+0xd2/0x110 [ 26.886826] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 26.893119] [] __sk_destruct+0x55/0x590 [ 26.898714] [] ? sock_release+0x1c0/0x1c0 [ 26.904480] [] sk_destruct+0x63/0x80 [ 26.909816] [] __sk_free+0x4f/0x220 [ 26.915061] [] sk_free+0x2b/0x40 [ 26.920050] [] pppol2tp_release+0x239/0x2e0 [ 26.925990] [] sock_release+0x96/0x1c0 [ 26.931495] [] sock_close+0x16/0x20 [ 26.936743] [] __fput+0x263/0x700 [ 26.941817] [] ____fput+0x15/0x20 [ 26.946892] [] task_work_run+0x10c/0x180 [ 26.952573] [] exit_to_usermode_loop+0xfc/0x120 [ 26.958858] [] do_syscall_64+0x364/0x490 [ 26.964629] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 26.971519] 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 [ 26.998252] RIP [] l2tp_session_free+0x11c/0x200 [ 27.004748] RSP [ 27.008352] CR2: 0000000000000080 [ 27.012926] ---[ end trace dc3bf9eb0806d8b9 ]--- [ 27.017874] Kernel panic - not syncing: Fatal exception [ 27.023577] Dumping ftrace buffer: [ 27.027094] (ftrace buffer empty) [ 27.030776] Kernel Offset: disabled [ 27.034374] Rebooting in 86400 seconds..