[....] 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[ 15.169806] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.541138] random: sshd: uninitialized urandom read (32 bytes read) [ 17.789332] random: sshd: uninitialized urandom read (32 bytes read) [ 18.250854] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.38' (ECDSA) to the list of known hosts. [ 23.813673] urandom_read: 1 callbacks suppressed [ 23.813677] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 24.031094] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 24.039319] IP: [] l2tp_session_free+0x11c/0x200 [ 24.045741] PGD 1c7203067 [ 24.048383] PUD 1c7146067 PMD 0 [ 24.051853] [ 24.053475] Oops: 0002 [#1] PREEMPT SMP KASAN [ 24.057947] Dumping ftrace buffer: [ 24.061459] (ftrace buffer empty) [ 24.065139] Modules linked in: [ 24.068419] CPU: 0 PID: 3795 Comm: syz-executor832 Not tainted 4.9.117-g8b21e85 #71 [ 24.076183] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 24.085515] task: ffff8801b76c8000 task.stack: ffff8801b5fa0000 [ 24.091541] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 24.100404] RSP: 0018:ffff8801b5fa7ca0 EFLAGS: 00010246 [ 24.105825] RAX: dffffc0000000000 RBX: ffff8801b5e22780 RCX: 0000000000000000 [ 24.113069] RDX: 1ffff100394b5ba0 RSI: ffffffff836bf8f1 RDI: ffff8801ca5add00 [ 24.120311] RBP: ffff8801b5fa7cc0 R08: ffff8801b76c88e8 R09: 0000000000000000 [ 24.127551] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801ca5adb80 [ 24.134795] R13: ffff8801b5e22788 R14: 0000000000000000 R15: ffffffff83015be0 [ 24.142039] FS: 000000000267a880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 24.150234] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 24.156086] CR2: 0000000000000080 CR3: 00000001c14b2000 CR4: 00000000001606f0 [ 24.163332] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 24.170575] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 24.177815] Stack: [ 24.179936] ffff8801b5934c80 ffff8801b5e22780 ffff8801b5935050 ffff8801b5934f58 [ 24.187931] ffff8801b5fa7ce8 ffffffff836c7202 ffff8801b59350c0 ffff8801b5934c80 [ 24.195925] ffffffff836c7130 ffff8801b5fa7d20 ffffffff83023095 ffff8801b59350c0 [ 24.203921] Call Trace: [ 24.206487] [] pppol2tp_session_destruct+0xd2/0x110 [ 24.213124] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 24.219414] [] __sk_destruct+0x55/0x590 [ 24.225010] [] ? sock_release+0x1c0/0x1c0 [ 24.230777] [] sk_destruct+0x63/0x80 [ 24.236111] [] __sk_free+0x4f/0x220 [ 24.241375] [] sk_free+0x2b/0x40 [ 24.246361] [] pppol2tp_release+0x239/0x2e0 [ 24.252315] [] sock_release+0x96/0x1c0 [ 24.257822] [] sock_close+0x16/0x20 [ 24.263071] [] __fput+0x263/0x700 [ 24.268143] [] ____fput+0x15/0x20 [ 24.273218] [] task_work_run+0x10c/0x180 [ 24.278900] [] exit_to_usermode_loop+0xfc/0x120 [ 24.285189] [] do_syscall_64+0x364/0x490 [ 24.290870] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 24.297761] 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 [ 24.324587] RIP [] l2tp_session_free+0x11c/0x200 [ 24.331089] RSP [ 24.334687] CR2: 0000000000000080 [ 24.338312] ---[ end trace c1e7c3372c144128 ]--- [ 24.343069] Kernel panic - not syncing: Fatal exception [ 24.348912] Dumping ftrace buffer: [ 24.352424] (ftrace buffer empty) [ 24.356105] Kernel Offset: disabled [ 24.359704] Rebooting in 86400 seconds..