[....] 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[ 13.712913] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 15.153091] random: sshd: uninitialized urandom read (32 bytes read) [ 15.318159] random: sshd: uninitialized urandom read (32 bytes read) [ 15.814389] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.53' (ECDSA) to the list of known hosts. [ 21.502202] urandom_read: 1 callbacks suppressed [ 21.502205] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 21.704109] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 21.712392] IP: [] l2tp_session_free+0x11c/0x200 [ 21.718867] PGD 1bf704067 [ 21.721516] PUD 1bf12d067 PMD 0 [ 21.725019] [ 21.726650] Oops: 0002 [#1] PREEMPT SMP KASAN [ 21.731126] Dumping ftrace buffer: [ 21.734650] (ftrace buffer empty) [ 21.738343] Modules linked in: [ 21.741646] CPU: 0 PID: 3728 Comm: syz-executor424 Not tainted 4.9.124-g09eb2ba #83 [ 21.749419] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 21.758756] task: ffff8801bf6e0000 task.stack: ffff8801bebc8000 [ 21.764819] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 21.773681] RSP: 0018:ffff8801bebcfc98 EFLAGS: 00010246 [ 21.779113] RAX: dffffc0000000000 RBX: ffff8801bed97900 RCX: 0000000000000000 [ 21.786365] RDX: 1ffff10037ef1ab0 RSI: ffffffff836c4711 RDI: ffff8801bf78d580 [ 21.793617] RBP: ffff8801bebcfcb8 R08: ffff8801bf6e08e8 R09: 0000000000000000 [ 21.800873] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801bf78d400 [ 21.808128] R13: ffff8801bed97908 R14: 0000000000000000 R15: 0000000000000000 [ 21.815384] FS: 0000000000e8e880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 21.823603] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 21.829468] CR2: 0000000000000080 CR3: 00000001cacd8000 CR4: 00000000001606f0 [ 21.836721] Stack: [ 21.838853] ffff8801be9be600 ffff8801bed97900 ffff8801be9be9d0 ffff8801be9be8d8 [ 21.846922] ffff8801bebcfce0 ffffffff836cc022 ffff8801be9bea40 ffff8801be9be600 [ 21.855032] ffffffff836cbf50 ffff8801bebcfd18 ffffffff830281f5 ffff8801be9bea40 [ 21.863082] Call Trace: [ 21.865651] [] pppol2tp_session_destruct+0xd2/0x110 [ 21.872302] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 21.878670] [] __sk_destruct+0x55/0x590 [ 21.884279] [] sk_destruct+0x63/0x80 [ 21.889630] [] __sk_free+0x4f/0x220 [ 21.894892] [] sk_free+0x2b/0x40 [ 21.899897] [] pppol2tp_release+0x239/0x2e0 [ 21.905852] [] __sock_release+0xd7/0x260 [ 21.911544] [] ? __sock_release+0x260/0x260 [ 21.917497] [] sock_close+0x19/0x20 [ 21.922757] [] __fput+0x263/0x700 [ 21.927868] [] ____fput+0x15/0x20 [ 21.932955] [] task_work_run+0x10c/0x180 [ 21.938652] [] exit_to_usermode_loop+0xfc/0x120 [ 21.944955] [] do_syscall_64+0x364/0x490 [ 21.950651] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 21.957555] 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 a5 c5 c9 fd 4c 89 ea 48 b8 00 [ 21.985214] RIP [] l2tp_session_free+0x11c/0x200 [ 21.991730] RSP [ 21.995335] CR2: 0000000000000080 [ 21.999105] ---[ end trace e584a8f8b1ebb23b ]--- [ 22.003883] Kernel panic - not syncing: Fatal exception [ 22.009635] Dumping ftrace buffer: [ 22.013169] (ftrace buffer empty) [ 22.016861] Kernel Offset: disabled [ 22.020472] Rebooting in 86400 seconds..