[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.234388] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 22.072676] random: sshd: uninitialized urandom read (32 bytes read) [ 22.542585] random: sshd: uninitialized urandom read (32 bytes read) [ 23.215866] random: sshd: uninitialized urandom read (32 bytes read) [ 26.313558] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.30' (ECDSA) to the list of known hosts. [ 31.707056] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 31.908031] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 31.916251] IP: [] l2tp_session_free+0x11c/0x200 [ 31.922666] PGD 1cb125067 [ 31.925305] PUD 1cb114067 PMD 0 [ 31.928787] [ 31.930405] Oops: 0002 [#1] PREEMPT SMP KASAN [ 31.934871] Dumping ftrace buffer: [ 31.938380] (ftrace buffer empty) [ 31.942062] Modules linked in: [ 31.945342] CPU: 0 PID: 3798 Comm: syz-executor555 Not tainted 4.9.113-g47bbcd6 #62 [ 31.953105] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 31.962428] task: ffff8801b90c6000 task.stack: ffff8801b6410000 [ 31.968453] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 31.977304] RSP: 0018:ffff8801b6417ca0 EFLAGS: 00010246 [ 31.982721] RAX: dffffc0000000000 RBX: ffff8801c80dfb80 RCX: 0000000000000000 [ 31.989959] RDX: 1ffff10039266570 RSI: ffffffff836bcce1 RDI: ffff8801c9332b80 [ 31.997198] RBP: ffff8801b6417cc0 R08: ffff8801b90c68e8 R09: 0000000000000000 [ 32.004438] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c9332a00 [ 32.011678] R13: ffff8801c80dfb88 R14: 0000000000000000 R15: ffffffff83013be0 [ 32.018926] FS: 0000000000705880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 32.027128] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 32.032985] CR2: 0000000000000080 CR3: 00000001d92b8000 CR4: 00000000001606f0 [ 32.040227] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 32.047467] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 32.054706] Stack: [ 32.056826] ffff8801d8d29100 ffff8801c80dfb80 ffff8801d8d294d0 ffff8801d8d293d8 [ 32.064801] ffff8801b6417ce8 ffffffff836c45f2 ffff8801d8d29540 ffff8801d8d29100 [ 32.072862] ffffffff836c4520 ffff8801b6417d20 ffffffff83021095 ffff8801d8d29540 [ 32.080834] Call Trace: [ 32.083393] [] pppol2tp_session_destruct+0xd2/0x110 [ 32.090029] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 32.096326] [] __sk_destruct+0x55/0x590 [ 32.101921] [] ? sock_release+0x1c0/0x1c0 [ 32.107688] [] sk_destruct+0x63/0x80 [ 32.113029] [] __sk_free+0x4f/0x220 [ 32.118275] [] sk_free+0x2b/0x40 [ 32.123259] [] pppol2tp_release+0x239/0x2e0 [ 32.129200] [] sock_release+0x96/0x1c0 [ 32.134706] [] sock_close+0x16/0x20 [ 32.139961] [] __fput+0x263/0x700 [ 32.145032] [] ____fput+0x15/0x20 [ 32.150108] [] task_work_run+0x10c/0x180 [ 32.155788] [] exit_to_usermode_loop+0xfc/0x120 [ 32.162077] [] do_syscall_64+0x364/0x490 [ 32.167756] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 32.174648] 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 55 1d ca fd 4c 89 ea 48 b8 00 [ 32.201329] RIP [] l2tp_session_free+0x11c/0x200 [ 32.207863] RSP [ 32.211461] CR2: 0000000000000080 [ 32.214949] ---[ end trace ba43458fee6262b8 ]--- [ 32.219691] Kernel panic - not syncing: Fatal exception [ 32.225413] Dumping ftrace buffer: [ 32.228956] (ftrace buffer empty) [ 32.232640] Kernel Offset: disabled [ 32.236358] Rebooting in 86400 seconds..