[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.641335] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.654999] random: sshd: uninitialized urandom read (32 bytes read) [ 21.080702] random: sshd: uninitialized urandom read (32 bytes read) [ 21.587673] random: sshd: uninitialized urandom read (32 bytes read) [ 21.722531] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.15.204' (ECDSA) to the list of known hosts. [ 27.141879] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 27.338206] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 27.346422] IP: [] l2tp_session_free+0x11c/0x200 [ 27.352842] PGD 1c5995067 [ 27.355486] PUD 1c2c14067 PMD 0 [ 27.358968] [ 27.360593] Oops: 0002 [#1] PREEMPT SMP KASAN [ 27.365070] Dumping ftrace buffer: [ 27.368582] (ftrace buffer empty) [ 27.372279] Modules linked in: [ 27.375562] CPU: 0 PID: 3797 Comm: syz-executor510 Not tainted 4.9.117-g8b21e85 #71 [ 27.383326] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.392664] task: ffff8801ba37e000 task.stack: ffff8801d9480000 [ 27.398692] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 27.407559] RSP: 0018:ffff8801d9487ca0 EFLAGS: 00010246 [ 27.412980] RAX: dffffc0000000000 RBX: ffff8801d96d2a00 RCX: 0000000000000000 [ 27.420223] RDX: 1ffff1003953cdc0 RSI: ffffffff836bf8f1 RDI: ffff8801ca9e6e00 [ 27.427482] RBP: ffff8801d9487cc0 R08: ffff8801ba37e8e8 R09: 0000000000000000 [ 27.434725] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801ca9e6c80 [ 27.441965] R13: ffff8801d96d2a08 R14: 0000000000000000 R15: ffffffff83015be0 [ 27.449218] FS: 0000000001bd4880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 27.457427] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 27.463297] CR2: 0000000000000080 CR3: 00000001d9541000 CR4: 00000000001606f0 [ 27.470546] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 27.477797] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 27.485045] Stack: [ 27.487169] ffff8801d95a5d80 ffff8801d96d2a00 ffff8801d95a6150 ffff8801d95a6058 [ 27.495149] ffff8801d9487ce8 ffffffff836c7202 ffff8801d95a61c0 ffff8801d95a5d80 [ 27.503141] ffffffff836c7130 ffff8801d9487d20 ffffffff83023095 ffff8801d95a61c0 [ 27.511135] Call Trace: [ 27.513712] [] pppol2tp_session_destruct+0xd2/0x110 [ 27.520353] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 27.526645] [] __sk_destruct+0x55/0x590 [ 27.532241] [] ? sock_release+0x1c0/0x1c0 [ 27.538023] [] sk_destruct+0x63/0x80 [ 27.543359] [] __sk_free+0x4f/0x220 [ 27.548608] [] sk_free+0x2b/0x40 [ 27.553594] [] pppol2tp_release+0x239/0x2e0 [ 27.559537] [] sock_release+0x96/0x1c0 [ 27.565047] [] sock_close+0x16/0x20 [ 27.570298] [] __fput+0x263/0x700 [ 27.575376] [] ____fput+0x15/0x20 [ 27.580465] [] task_work_run+0x10c/0x180 [ 27.586151] [] exit_to_usermode_loop+0xfc/0x120 [ 27.592443] [] do_syscall_64+0x364/0x490 [ 27.598130] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 27.605027] 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 [ 27.632016] RIP [] l2tp_session_free+0x11c/0x200 [ 27.638576] RSP [ 27.642173] CR2: 0000000000000080 [ 27.645796] ---[ end trace 7e2bfff171d49389 ]--- [ 27.650553] Kernel panic - not syncing: Fatal exception [ 27.656213] Dumping ftrace buffer: [ 27.659726] (ftrace buffer empty) [ 27.663410] Kernel Offset: disabled [ 27.667006] Rebooting in 86400 seconds..