[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.500875] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 23.455373] random: sshd: uninitialized urandom read (32 bytes read) [ 23.844368] random: sshd: uninitialized urandom read (32 bytes read) [ 24.191171] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.49' (ECDSA) to the list of known hosts. [ 29.749491] urandom_read: 1 callbacks suppressed [ 29.749495] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 29.959764] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 29.968024] IP: [] l2tp_session_free+0x11c/0x200 [ 29.974449] PGD 1cb31a067 [ 29.977089] PUD 1ba9e1067 PMD 0 [ 29.980678] [ 29.982308] Oops: 0002 [#1] PREEMPT SMP KASAN [ 29.986775] Dumping ftrace buffer: [ 29.990287] (ftrace buffer empty) [ 29.993985] Modules linked in: [ 29.997271] CPU: 1 PID: 3805 Comm: syz-executor774 Not tainted 4.9.117-g8b21e85 #71 [ 30.005036] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 30.014364] task: ffff8801b7388000 task.stack: ffff8801b5aa8000 [ 30.020393] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 30.029250] RSP: 0018:ffff8801b5aafca0 EFLAGS: 00010246 [ 30.034675] RAX: dffffc0000000000 RBX: ffff8801c9c30500 RCX: 0000000000000000 [ 30.041921] RDX: 1ffff10036b20e10 RSI: ffffffff836bf8f1 RDI: ffff8801b5907080 [ 30.049172] RBP: ffff8801b5aafcc0 R08: ffff8801b73888e8 R09: 0000000000000000 [ 30.056428] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5906f00 [ 30.063669] R13: ffff8801c9c30508 R14: 0000000000000000 R15: ffffffff83015be0 [ 30.070923] FS: 0000000001770880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 30.079136] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 30.084989] CR2: 0000000000000080 CR3: 00000001cb419000 CR4: 00000000001606f0 [ 30.092233] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 30.099484] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 30.106727] Stack: [ 30.108850] ffff8801c9861100 ffff8801c9c30500 ffff8801c98614d0 ffff8801c98613d8 [ 30.116834] ffff8801b5aafce8 ffffffff836c7202 ffff8801c9861540 ffff8801c9861100 [ 30.124825] ffffffff836c7130 ffff8801b5aafd20 ffffffff83023095 ffff8801c9861540 [ 30.132814] Call Trace: [ 30.135380] [] pppol2tp_session_destruct+0xd2/0x110 [ 30.142017] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 30.148312] [] __sk_destruct+0x55/0x590 [ 30.153919] [] ? sock_release+0x1c0/0x1c0 [ 30.159690] [] sk_destruct+0x63/0x80 [ 30.165035] [] __sk_free+0x4f/0x220 [ 30.170282] [] sk_free+0x2b/0x40 [ 30.175269] [] pppol2tp_release+0x239/0x2e0 [ 30.181233] [] sock_release+0x96/0x1c0 [ 30.186757] [] sock_close+0x16/0x20 [ 30.192014] [] __fput+0x263/0x700 [ 30.197095] [] ____fput+0x15/0x20 [ 30.202173] [] task_work_run+0x10c/0x180 [ 30.207858] [] exit_to_usermode_loop+0xfc/0x120 [ 30.214235] [] do_syscall_64+0x364/0x490 [ 30.219920] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 30.226819] 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 [ 30.253659] RIP [] l2tp_session_free+0x11c/0x200 [ 30.260168] RSP [ 30.263762] CR2: 0000000000000080 [ 30.267258] ---[ end trace 9555b8bb4643c2cf ]--- [ 30.272045] Kernel panic - not syncing: Fatal exception [ 30.277756] Dumping ftrace buffer: [ 30.281283] (ftrace buffer empty) [ 30.284980] Kernel Offset: disabled [ 30.288595] Rebooting in 86400 seconds..