[....] 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[ 12.338175] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 28.005988] random: sshd: uninitialized urandom read (32 bytes read) [ 28.401159] random: sshd: uninitialized urandom read (32 bytes read) [ 28.729129] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.16' (ECDSA) to the list of known hosts. [ 34.288108] urandom_read: 1 callbacks suppressed [ 34.288112] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 34.486352] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 34.494608] IP: [] l2tp_session_free+0x11c/0x200 [ 34.501032] PGD 1cb18e067 [ 34.503672] PUD 1cb71a067 PMD 0 [ 34.507161] [ 34.508781] Oops: 0002 [#1] PREEMPT SMP KASAN [ 34.513256] Dumping ftrace buffer: [ 34.516790] (ftrace buffer empty) [ 34.520480] Modules linked in: [ 34.523803] CPU: 0 PID: 3812 Comm: syz-executor104 Not tainted 4.9.117-g8b21e85 #19 [ 34.531573] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 34.540912] task: ffff8801b7090000 task.stack: ffff8801b6730000 [ 34.546944] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 34.555798] RSP: 0018:ffff8801b6737ca0 EFLAGS: 00010246 [ 34.561222] RAX: dffffc0000000000 RBX: ffff8801b5e87400 RCX: 0000000000000000 [ 34.568465] RDX: 1ffff10036ba0d70 RSI: ffffffff836bf8f1 RDI: ffff8801b5d06b80 [ 34.575710] RBP: ffff8801b6737cc0 R08: ffff8801b70908e8 R09: 0000000000000000 [ 34.582958] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5d06a00 [ 34.590205] R13: ffff8801b5e87408 R14: 0000000000000000 R15: ffffffff83015be0 [ 34.597452] FS: 0000000000a5a880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 34.605663] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 34.611519] CR2: 0000000000000080 CR3: 00000001ca122000 CR4: 00000000001606f0 [ 34.618767] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 34.626014] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 34.633271] Stack: [ 34.635398] ffff8801b5d09100 ffff8801b5e87400 ffff8801b5d094d0 ffff8801b5d093d8 [ 34.643386] ffff8801b6737ce8 ffffffff836c7202 ffff8801b5d09540 ffff8801b5d09100 [ 34.651377] ffffffff836c7130 ffff8801b6737d20 ffffffff83023095 ffff8801b5d09540 [ 34.659369] Call Trace: [ 34.661936] [] pppol2tp_session_destruct+0xd2/0x110 [ 34.668576] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 34.674871] [] __sk_destruct+0x55/0x590 [ 34.680471] [] ? sock_release+0x1c0/0x1c0 [ 34.686251] [] sk_destruct+0x63/0x80 [ 34.691587] [] __sk_free+0x4f/0x220 [ 34.696839] [] sk_free+0x2b/0x40 [ 34.701827] [] pppol2tp_release+0x239/0x2e0 [ 34.707773] [] sock_release+0x96/0x1c0 [ 34.713284] [] sock_close+0x16/0x20 [ 34.718537] [] __fput+0x263/0x700 [ 34.723615] [] ____fput+0x15/0x20 [ 34.728694] [] task_work_run+0x10c/0x180 [ 34.734379] [] exit_to_usermode_loop+0xfc/0x120 [ 34.740683] [] do_syscall_64+0x364/0x490 [ 34.746380] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 34.753274] 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 [ 34.780223] RIP [] l2tp_session_free+0x11c/0x200 [ 34.786727] RSP [ 34.790325] CR2: 0000000000000080 [ 34.794003] ---[ end trace 9ac2b6cadc10a6b8 ]--- [ 34.798754] Kernel panic - not syncing: Fatal exception [ 34.804502] Dumping ftrace buffer: [ 34.808033] (ftrace buffer empty) [ 34.811720] Kernel Offset: disabled [ 34.815327] Rebooting in 86400 seconds..