[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.584883] 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: [ 28.447575] random: sshd: uninitialized urandom read (32 bytes read) [ 28.794603] random: sshd: uninitialized urandom read (32 bytes read) [ 29.170866] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.40' (ECDSA) to the list of known hosts. [ 34.736226] urandom_read: 1 callbacks suppressed [ 34.736229] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 34.942858] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 34.951075] IP: [<ffffffff836bf91c>] l2tp_session_free+0x11c/0x200 [ 34.957514] PGD 1c7ef0067 [ 34.960189] PUD 1c8727067 PMD 0 [ 34.963662] [ 34.965286] Oops: 0002 [#1] PREEMPT SMP KASAN [ 34.969757] Dumping ftrace buffer: [ 34.973265] (ftrace buffer empty) [ 34.976946] Modules linked in: [ 34.980231] CPU: 1 PID: 3807 Comm: syz-executor939 Not tainted 4.9.117-g8b21e85 #19 [ 34.987995] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 34.997321] task: ffff8801b8601800 task.stack: ffff8801d92d8000 [ 35.003349] RIP: 0010:[<ffffffff836bf91c>] [<ffffffff836bf91c>] l2tp_session_free+0x11c/0x200 [ 35.012188] RSP: 0018:ffff8801d92dfca0 EFLAGS: 00010246 [ 35.017604] RAX: dffffc0000000000 RBX: ffff8801c92d2280 RCX: 0000000000000000 [ 35.024847] RDX: 1ffff1003b317520 RSI: ffffffff836bf8f1 RDI: ffff8801d98ba900 [ 35.032086] RBP: ffff8801d92dfcc0 R08: ffff8801b86020e8 R09: 0000000000000000 [ 35.039337] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801d98ba780 [ 35.046577] R13: ffff8801c92d2288 R14: 0000000000000000 R15: ffffffff83015be0 [ 35.053822] FS: 0000000000f59880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 35.062015] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 35.067882] CR2: 0000000000000080 CR3: 00000001c6bef000 CR4: 00000000001606f0 [ 35.075140] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 35.082382] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 35.089623] Stack: [ 35.091741] ffff8801b6c4b300 ffff8801c92d2280 ffff8801b6c4b6d0 ffff8801b6c4b5d8 [ 35.099708] ffff8801d92dfce8 ffffffff836c7202 ffff8801b6c4b740 ffff8801b6c4b300 [ 35.107686] ffffffff836c7130 ffff8801d92dfd20 ffffffff83023095 ffff8801b6c4b740 [ 35.115689] Call Trace: [ 35.118262] [<ffffffff836c7202>] pppol2tp_session_destruct+0xd2/0x110 [ 35.124897] [<ffffffff836c7130>] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 35.131187] [<ffffffff83023095>] __sk_destruct+0x55/0x590 [ 35.136782] [<ffffffff83015be0>] ? sock_release+0x1c0/0x1c0 [ 35.142560] [<ffffffff8302ab23>] sk_destruct+0x63/0x80 [ 35.147904] [<ffffffff8302ab8f>] __sk_free+0x4f/0x220 [ 35.153147] [<ffffffff8302ad8b>] sk_free+0x2b/0x40 [ 35.158144] [<ffffffff836ca509>] pppol2tp_release+0x239/0x2e0 [ 35.164082] [<ffffffff83015ab6>] sock_release+0x96/0x1c0 [ 35.169586] [<ffffffff83015bf6>] sock_close+0x16/0x20 [ 35.174832] [<ffffffff81578693>] __fput+0x263/0x700 [ 35.179908] [<ffffffff81578bb5>] ____fput+0x15/0x20 [ 35.184989] [<ffffffff8119838c>] task_work_run+0x10c/0x180 [ 35.190673] [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 [ 35.196965] [<ffffffff810064d4>] do_syscall_64+0x364/0x490 [ 35.202658] [<ffffffff839fcc13>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 35.209552] 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 e5 f1 c9 fd 4c 89 ea 48 b8 00 [ 35.236406] RIP [<ffffffff836bf91c>] l2tp_session_free+0x11c/0x200 [ 35.242904] RSP <ffff8801d92dfca0> [ 35.246501] CR2: 0000000000000080 [ 35.250107] ---[ end trace 51b41f83c285b8bb ]--- [ 35.254862] Kernel panic - not syncing: Fatal exception [ 35.260499] Dumping ftrace buffer: [ 35.264014] (ftrace buffer empty) [ 35.267694] Kernel Offset: disabled [ 35.271293] Rebooting in 86400 seconds..