[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.013531] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 16.741790] random: sshd: uninitialized urandom read (32 bytes read) [ 17.081950] random: sshd: uninitialized urandom read (32 bytes read) [ 17.625260] random: sshd: uninitialized urandom read (32 bytes read) [ 17.768664] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.15.204' (ECDSA) to the list of known hosts. [ 23.208334] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 23.394602] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 23.402856] IP: [] l2tp_session_free+0x11c/0x200 [ 23.409286] PGD 1c4fb1067 [ 23.411934] PUD 1c4fb7067 PMD 0 [ 23.415419] [ 23.417049] Oops: 0002 [#1] PREEMPT SMP KASAN [ 23.421527] Dumping ftrace buffer: [ 23.425045] (ftrace buffer empty) [ 23.428738] Modules linked in: [ 23.432029] CPU: 0 PID: 3799 Comm: syz-executor527 Not tainted 4.9.117-g8b21e85 #71 [ 23.439801] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 23.449138] task: ffff8801c4d68000 task.stack: ffff8801b6150000 [ 23.455171] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 23.464031] RSP: 0018:ffff8801b6157ca0 EFLAGS: 00010246 [ 23.469454] RAX: dffffc0000000000 RBX: ffff8801b69c0a00 RCX: 0000000000000000 [ 23.476700] RDX: 1ffff10036cd2350 RSI: ffffffff836bf8f1 RDI: ffff8801b6691a80 [ 23.483964] RBP: ffff8801b6157cc0 R08: ffff8801c4d688e8 R09: 0000000000000000 [ 23.491226] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b6691900 [ 23.498476] R13: ffff8801b69c0a08 R14: 0000000000000000 R15: ffffffff83015be0 [ 23.505730] FS: 0000000000f24880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 23.513933] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 23.519797] CR2: 0000000000000080 CR3: 00000001d9712000 CR4: 00000000001606f0 [ 23.527058] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 23.534309] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 23.541559] Stack: [ 23.543689] ffff8801d9088000 ffff8801b69c0a00 ffff8801d90883d0 ffff8801d90882d8 [ 23.551713] ffff8801b6157ce8 ffffffff836c7202 ffff8801d9088440 ffff8801d9088000 [ 23.559719] ffffffff836c7130 ffff8801b6157d20 ffffffff83023095 ffff8801d9088440 [ 23.567735] Call Trace: [ 23.570321] [] pppol2tp_session_destruct+0xd2/0x110 [ 23.576980] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 23.583292] [] __sk_destruct+0x55/0x590 [ 23.588910] [] ? sock_release+0x1c0/0x1c0 [ 23.594704] [] sk_destruct+0x63/0x80 [ 23.600059] [] __sk_free+0x4f/0x220 [ 23.605327] [] sk_free+0x2b/0x40 [ 23.610337] [] pppol2tp_release+0x239/0x2e0 [ 23.616302] [] sock_release+0x96/0x1c0 [ 23.621830] [] sock_close+0x16/0x20 [ 23.627099] [] __fput+0x263/0x700 [ 23.632192] [] ____fput+0x15/0x20 [ 23.637302] [] task_work_run+0x10c/0x180 [ 23.643008] [] exit_to_usermode_loop+0xfc/0x120 [ 23.649321] [] do_syscall_64+0x364/0x490 [ 23.655029] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 23.661943] 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 [ 23.689108] RIP [] l2tp_session_free+0x11c/0x200 [ 23.695625] RSP [ 23.699233] CR2: 0000000000000080 [ 23.703833] ---[ end trace 801c269e82d1b5d1 ]--- [ 23.708617] Kernel panic - not syncing: Fatal exception [ 23.714285] Dumping ftrace buffer: [ 23.717814] (ftrace buffer empty) [ 23.721507] Kernel Offset: disabled [ 23.725111] Rebooting in 86400 seconds..