[....] 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[ 12.931091] 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: [ 14.898176] random: sshd: uninitialized urandom read (32 bytes read) [ 15.089617] random: sshd: uninitialized urandom read (32 bytes read) [ 15.590378] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.20' (ECDSA) to the list of known hosts. [ 26.131081] urandom_read: 1 callbacks suppressed [ 26.131085] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 26.331536] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 26.339776] IP: [<ffffffff836bf9cc>] l2tp_session_free+0x11c/0x200 [ 26.346230] PGD 1c81fe067 [ 26.348884] PUD 1ca125067 PMD 0 [ 26.352369] [ 26.353992] Oops: 0002 [#1] PREEMPT SMP KASAN [ 26.358515] Dumping ftrace buffer: [ 26.362038] (ftrace buffer empty) [ 26.365727] Modules linked in: [ 26.369058] CPU: 1 PID: 3800 Comm: syz-executor212 Not tainted 4.9.119-g9dc978d #75 [ 26.376828] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 26.386168] task: ffff8801b7074800 task.stack: ffff8801d9730000 [ 26.392215] RIP: 0010:[<ffffffff836bf9cc>] [<ffffffff836bf9cc>] l2tp_session_free+0x11c/0x200 [ 26.401178] RSP: 0018:ffff8801d9737ca0 EFLAGS: 00010246 [ 26.406603] RAX: dffffc0000000000 RBX: ffff8801b6486a00 RCX: 0000000000000000 [ 26.413856] RDX: 1ffff100371f3eb0 RSI: ffffffff836bf9a1 RDI: ffff8801b8f9f580 [ 26.421105] RBP: ffff8801d9737cc0 R08: ffff8801b70750e8 R09: 0000000000000000 [ 26.428365] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b8f9f400 [ 26.435634] R13: ffff8801b6486a08 R14: 0000000000000000 R15: ffffffff83015be0 [ 26.442882] FS: 00000000011bb880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 26.451083] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 26.456942] CR2: 0000000000000080 CR3: 00000001b6572000 CR4: 00000000001606f0 [ 26.464198] Stack: [ 26.466332] ffff8801d9480000 ffff8801b6486a00 ffff8801d94803d0 ffff8801d94802d8 [ 26.474338] ffff8801d9737ce8 ffffffff836c72b2 ffff8801d9480440 ffff8801d9480000 [ 26.482372] ffffffff836c71e0 ffff8801d9737d20 ffffffff830230f5 ffff8801d9480440 [ 26.490534] Call Trace: [ 26.493118] [<ffffffff836c72b2>] pppol2tp_session_destruct+0xd2/0x110 [ 26.499785] [<ffffffff836c71e0>] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 26.506091] [<ffffffff830230f5>] __sk_destruct+0x55/0x590 [ 26.511715] [<ffffffff83015be0>] ? sock_release+0x1c0/0x1c0 [ 26.517511] [<ffffffff8302ab83>] sk_destruct+0x63/0x80 [ 26.522855] [<ffffffff8302abef>] __sk_free+0x4f/0x220 [ 26.528169] [<ffffffff8302adeb>] sk_free+0x2b/0x40 [ 26.533183] [<ffffffff836ca5b9>] pppol2tp_release+0x239/0x2e0 [ 26.539200] [<ffffffff83015ab6>] sock_release+0x96/0x1c0 [ 26.544726] [<ffffffff83015bf6>] sock_close+0x16/0x20 [ 26.549984] [<ffffffff81578693>] __fput+0x263/0x700 [ 26.555068] [<ffffffff81578bb5>] ____fput+0x15/0x20 [ 26.560150] [<ffffffff8119838c>] task_work_run+0x10c/0x180 [ 26.565843] [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 [ 26.572146] [<ffffffff810064d4>] do_syscall_64+0x364/0x490 [ 26.577850] [<ffffffff839fccd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 26.584752] 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 f5 f0 c9 fd 4c 89 ea 48 b8 00 [ 26.611831] RIP [<ffffffff836bf9cc>] l2tp_session_free+0x11c/0x200 [ 26.618366] RSP <ffff8801d9737ca0> [ 26.621965] CR2: 0000000000000080 [ 26.625633] ---[ end trace 2fec20f1d8359bd5 ]--- [ 26.630379] Kernel panic - not syncing: Fatal exception [ 26.636148] Dumping ftrace buffer: [ 26.639679] (ftrace buffer empty) [ 26.643379] Kernel Offset: disabled [ 26.646991] Rebooting in 86400 seconds..