[....] 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[ 13.033123] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.453622] random: sshd: uninitialized urandom read (32 bytes read) [ 17.663061] random: sshd: uninitialized urandom read (32 bytes read) [ 18.191429] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.25' (ECDSA) to the list of known hosts. [ 24.021676] urandom_read: 1 callbacks suppressed [ 24.021679] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 24.239507] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 24.247815] IP: [] l2tp_session_free+0x11c/0x200 [ 24.254228] PGD 1cae4b067 [ 24.256866] PUD 1b868a067 PMD 0 [ 24.260348] [ 24.261964] Oops: 0002 [#1] PREEMPT SMP KASAN [ 24.266429] Dumping ftrace buffer: [ 24.269943] (ftrace buffer empty) [ 24.273623] Modules linked in: [ 24.276922] CPU: 0 PID: 3799 Comm: syz-executor354 Not tainted 4.9.117-g8b21e85 #19 [ 24.284683] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 24.294004] task: ffff8801b8c26000 task.stack: ffff8801d9768000 [ 24.300042] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 24.308885] RSP: 0018:ffff8801d976fca0 EFLAGS: 00010246 [ 24.314304] RAX: dffffc0000000000 RBX: ffff8801c9e5d180 RCX: 0000000000000000 [ 24.321577] RDX: 1ffff10036cb56b0 RSI: ffffffff836bf8f1 RDI: ffff8801b65ab580 [ 24.328818] RBP: ffff8801d976fcc0 R08: ffff8801b8c268e8 R09: 0000000000000000 [ 24.336059] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b65ab400 [ 24.343300] R13: ffff8801c9e5d188 R14: 0000000000000000 R15: ffffffff83015be0 [ 24.350543] FS: 0000000002194880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 24.358738] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 24.364591] CR2: 0000000000000080 CR3: 00000001c6108000 CR4: 00000000001606f0 [ 24.371835] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 24.379076] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 24.386315] Stack: [ 24.388436] ffff8801b7826e80 ffff8801c9e5d180 ffff8801b7827250 ffff8801b7827158 [ 24.396421] ffff8801d976fce8 ffffffff836c7202 ffff8801b78272c0 ffff8801b7826e80 [ 24.404400] ffffffff836c7130 ffff8801d976fd20 ffffffff83023095 ffff8801b78272c0 [ 24.412379] Call Trace: [ 24.414935] [] pppol2tp_session_destruct+0xd2/0x110 [ 24.421570] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 24.427864] [] __sk_destruct+0x55/0x590 [ 24.433462] [] ? sock_release+0x1c0/0x1c0 [ 24.439231] [] sk_destruct+0x63/0x80 [ 24.444565] [] __sk_free+0x4f/0x220 [ 24.449811] [] sk_free+0x2b/0x40 [ 24.454814] [] pppol2tp_release+0x239/0x2e0 [ 24.460755] [] sock_release+0x96/0x1c0 [ 24.466263] [] sock_close+0x16/0x20 [ 24.471509] [] __fput+0x263/0x700 [ 24.476596] [] ____fput+0x15/0x20 [ 24.481671] [] task_work_run+0x10c/0x180 [ 24.487351] [] exit_to_usermode_loop+0xfc/0x120 [ 24.493646] [] do_syscall_64+0x364/0x490 [ 24.499342] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 24.506233] 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 [ 24.533095] RIP [] l2tp_session_free+0x11c/0x200 [ 24.539611] RSP [ 24.543211] CR2: 0000000000000080 [ 24.547059] ---[ end trace 0c2617648ae6843e ]--- [ 24.551810] Kernel panic - not syncing: Fatal exception [ 24.557552] Dumping ftrace buffer: [ 24.561085] (ftrace buffer empty) [ 24.564766] Kernel Offset: disabled [ 24.568361] Rebooting in 86400 seconds..