[....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.000528] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 16.159508] random: sshd: uninitialized urandom read (32 bytes read) [ 16.608956] random: sshd: uninitialized urandom read (32 bytes read) [ 17.551188] random: sshd: uninitialized urandom read (32 bytes read) [ 17.681253] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.45' (ECDSA) to the list of known hosts. [ 23.098967] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 23.341070] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 23.349304] IP: [<ffffffff836bcd0c>] l2tp_session_free+0x11c/0x200 [ 23.355739] PGD 1ca6bf067 [ 23.358398] PUD 1b7ebc067 PMD 0 [ 23.361885] [ 23.363507] Oops: 0002 [#1] PREEMPT SMP KASAN [ 23.367975] Dumping ftrace buffer: [ 23.371487] (ftrace buffer empty) [ 23.375175] Modules linked in: [ 23.378476] CPU: 0 PID: 3800 Comm: syz-executor710 Not tainted 4.9.113-g47bbcd6 #62 [ 23.386243] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 23.395586] task: ffff8801b6e79800 task.stack: ffff8801d96e8000 [ 23.401643] RIP: 0010:[<ffffffff836bcd0c>] [<ffffffff836bcd0c>] l2tp_session_free+0x11c/0x200 [ 23.410592] RSP: 0018:ffff8801d96efca0 EFLAGS: 00010246 [ 23.416023] RAX: dffffc0000000000 RBX: ffff8801ca780780 RCX: 0000000000000000 [ 23.423275] RDX: 1ffff10036a04660 RSI: ffffffff836bcce1 RDI: ffff8801b5023300 [ 23.430540] RBP: ffff8801d96efcc0 R08: ffff8801b6e7a0e8 R09: 0000000000000000 [ 23.437876] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5023180 [ 23.445135] R13: ffff8801ca780788 R14: 0000000000000000 R15: ffffffff83013be0 [ 23.452385] FS: 00000000010ff880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 23.460589] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 23.466449] CR2: 0000000000000080 CR3: 00000001cd4f1000 CR4: 00000000001606f0 [ 23.473717] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 23.480972] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 23.488224] Stack: [ 23.490351] ffff8801c5116e80 ffff8801ca780780 ffff8801c5117250 ffff8801c5117158 [ 23.498376] ffff8801d96efce8 ffffffff836c45f2 ffff8801c51172c0 ffff8801c5116e80 [ 23.506379] ffffffff836c4520 ffff8801d96efd20 ffffffff83021095 ffff8801c51172c0 [ 23.514380] Call Trace: [ 23.516962] [<ffffffff836c45f2>] pppol2tp_session_destruct+0xd2/0x110 [ 23.523615] [<ffffffff836c4520>] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 23.529917] [<ffffffff83021095>] __sk_destruct+0x55/0x590 [ 23.535518] [<ffffffff83013be0>] ? sock_release+0x1c0/0x1c0 [ 23.541292] [<ffffffff83028b23>] sk_destruct+0x63/0x80 [ 23.546635] [<ffffffff83028b8f>] __sk_free+0x4f/0x220 [ 23.551894] [<ffffffff83028d8b>] sk_free+0x2b/0x40 [ 23.556896] [<ffffffff836c78f9>] pppol2tp_release+0x239/0x2e0 [ 23.562859] [<ffffffff83013ab6>] sock_release+0x96/0x1c0 [ 23.568380] [<ffffffff83013bf6>] sock_close+0x16/0x20 [ 23.573650] [<ffffffff815782e3>] __fput+0x263/0x700 [ 23.578730] [<ffffffff81578805>] ____fput+0x15/0x20 [ 23.583817] [<ffffffff8119838c>] task_work_run+0x10c/0x180 [ 23.589519] [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 [ 23.595836] [<ffffffff810064d4>] do_syscall_64+0x364/0x490 [ 23.601528] [<ffffffff839f9f93>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 23.608436] 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 <f0> 41 ff 8e 80 00 00 00 74 69 e8 55 1d ca fd 4c 89 ea 48 b8 00 [ 23.635516] RIP [<ffffffff836bcd0c>] l2tp_session_free+0x11c/0x200 [ 23.642031] RSP <ffff8801d96efca0> [ 23.645635] CR2: 0000000000000080 [ 23.649213] ---[ end trace 9d29f1e972c294fb ]--- [ 23.653980] Kernel panic - not syncing: Fatal exception [ 23.659849] Dumping ftrace buffer: [ 23.663384] (ftrace buffer empty) [ 23.667069] Kernel Offset: disabled [ 23.670670] Rebooting in 86400 seconds..