[....] 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[ 12.599327] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 21.610851] random: sshd: uninitialized urandom read (32 bytes read) [ 21.956339] random: sshd: uninitialized urandom read (32 bytes read) [ 22.446625] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.15.198' (ECDSA) to the list of known hosts. [ 28.001634] urandom_read: 1 callbacks suppressed [ 28.001638] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 28.234309] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 28.242551] IP: [] l2tp_session_free+0x11c/0x200 [ 28.248982] PGD 1c6ecf067 [ 28.251622] PUD 1c6eca067 PMD 0 [ 28.255098] [ 28.256717] Oops: 0002 [#1] PREEMPT SMP KASAN [ 28.261184] Dumping ftrace buffer: [ 28.264693] (ftrace buffer empty) [ 28.268376] Modules linked in: [ 28.271662] CPU: 1 PID: 3800 Comm: syz-executor853 Not tainted 4.9.117-g8b21e85 #71 [ 28.279425] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.288753] task: ffff8801b99d6000 task.stack: ffff8801d9b90000 [ 28.294781] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 28.303644] RSP: 0018:ffff8801d9b97ca0 EFLAGS: 00010246 [ 28.309074] RAX: dffffc0000000000 RBX: ffff8801b7784500 RCX: 0000000000000000 [ 28.316316] RDX: 1ffff10036de7b50 RSI: ffffffff836bf8f1 RDI: ffff8801b6f3da80 [ 28.323569] RBP: ffff8801d9b97cc0 R08: ffff8801b99d68e8 R09: 0000000000000000 [ 28.330817] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b6f3d900 [ 28.338075] R13: ffff8801b7784508 R14: 0000000000000000 R15: ffffffff83015be0 [ 28.345320] FS: 00000000014fb880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 28.353516] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 28.359370] CR2: 0000000000000080 CR3: 00000001c8f95000 CR4: 00000000001606f0 [ 28.366616] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 28.373858] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 28.381098] Stack: [ 28.383220] ffff8801b6eb3300 ffff8801b7784500 ffff8801b6eb36d0 ffff8801b6eb35d8 [ 28.391200] ffff8801d9b97ce8 ffffffff836c7202 ffff8801b6eb3740 ffff8801b6eb3300 [ 28.399179] ffffffff836c7130 ffff8801d9b97d20 ffffffff83023095 ffff8801b6eb3740 [ 28.407171] Call Trace: [ 28.409736] [] pppol2tp_session_destruct+0xd2/0x110 [ 28.416380] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 28.422674] [] __sk_destruct+0x55/0x590 [ 28.428290] [] ? sock_release+0x1c0/0x1c0 [ 28.434060] [] sk_destruct+0x63/0x80 [ 28.439467] [] __sk_free+0x4f/0x220 [ 28.444724] [] sk_free+0x2b/0x40 [ 28.449713] [] pppol2tp_release+0x239/0x2e0 [ 28.455659] [] sock_release+0x96/0x1c0 [ 28.461170] [] sock_close+0x16/0x20 [ 28.466420] [] __fput+0x263/0x700 [ 28.471504] [] ____fput+0x15/0x20 [ 28.476579] [] task_work_run+0x10c/0x180 [ 28.482260] [] exit_to_usermode_loop+0xfc/0x120 [ 28.488552] [] do_syscall_64+0x364/0x490 [ 28.494235] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 28.501131] 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 [ 28.527817] RIP [] l2tp_session_free+0x11c/0x200 [ 28.534314] RSP [ 28.537906] CR2: 0000000000000080 [ 28.541466] ---[ end trace 04c81e9de2f2a445 ]--- [ 28.546224] Kernel panic - not syncing: Fatal exception [ 28.551840] Dumping ftrace buffer: [ 28.555358] (ftrace buffer empty) [ 28.559041] Kernel Offset: disabled [ 28.562640] Rebooting in 86400 seconds..