[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.937014] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 14.718161] random: sshd: uninitialized urandom read (32 bytes read) [ 15.056230] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 15.553184] random: sshd: uninitialized urandom read (32 bytes read) [ 15.695826] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.49' (ECDSA) to the list of known hosts. [ 21.351825] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 21.549709] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 21.558066] IP: [] l2tp_session_free+0x11c/0x200 [ 21.564492] PGD 1c7cf1067 [ 21.567141] PUD 1c4c39067 PMD 0 [ 21.570656] [ 21.572284] Oops: 0002 [#1] PREEMPT SMP KASAN [ 21.576753] Dumping ftrace buffer: [ 21.580274] (ftrace buffer empty) [ 21.583963] Modules linked in: [ 21.587266] CPU: 0 PID: 3796 Comm: syz-executor913 Not tainted 4.9.123-g8dd3fc2 #79 [ 21.595055] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 21.604388] task: ffff8801bba8b000 task.stack: ffff8801b6320000 [ 21.610421] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 21.619292] RSP: 0018:ffff8801b6327ca0 EFLAGS: 00010246 [ 21.624715] RAX: dffffc0000000000 RBX: ffff8801b9755400 RCX: 0000000000000000 [ 21.631961] RDX: 1ffff10039682750 RSI: ffffffff836c4991 RDI: ffff8801cb413a80 [ 21.639206] RBP: ffff8801b6327cc0 R08: ffff8801bba8b8e8 R09: 0000000000000000 [ 21.646453] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cb413900 [ 21.653702] R13: ffff8801b9755408 R14: 0000000000000000 R15: ffffffff8301abe0 [ 21.660950] FS: 00000000015e8880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 21.669150] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 21.675018] CR2: 0000000000000080 CR3: 00000001c6d3b000 CR4: 00000000001606f0 [ 21.682284] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 21.689546] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 21.696797] Stack: [ 21.698927] ffff8801b6102200 ffff8801b9755400 ffff8801b61025d0 ffff8801b61024d8 [ 21.706926] ffff8801b6327ce8 ffffffff836cc2a2 ffff8801b6102640 ffff8801b6102200 [ 21.714980] ffffffff836cc1d0 ffff8801b6327d20 ffffffff830280f5 ffff8801b6102640 [ 21.722980] Call Trace: [ 21.725551] [] pppol2tp_session_destruct+0xd2/0x110 [ 21.732198] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 21.738496] [] __sk_destruct+0x55/0x590 [ 21.744114] [] ? sock_release+0x1c0/0x1c0 [ 21.749886] [] sk_destruct+0x63/0x80 [ 21.755225] [] __sk_free+0x4f/0x220 [ 21.760476] [] sk_free+0x2b/0x40 [ 21.765469] [] pppol2tp_release+0x239/0x2e0 [ 21.771418] [] sock_release+0x96/0x1c0 [ 21.776930] [] sock_close+0x16/0x20 [ 21.782198] [] __fput+0x263/0x700 [ 21.787280] [] ____fput+0x15/0x20 [ 21.792361] [] task_work_run+0x10c/0x180 [ 21.798055] [] exit_to_usermode_loop+0xfc/0x120 [ 21.804381] [] do_syscall_64+0x364/0x490 [ 21.810077] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 21.816996] 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 c3 c9 fd 4c 89 ea 48 b8 00 [ 21.844015] RIP [] l2tp_session_free+0x11c/0x200 [ 21.850524] RSP [ 21.854122] CR2: 0000000000000080 [ 21.857872] ---[ end trace 71a0a6312003930d ]--- [ 21.862635] Kernel panic - not syncing: Fatal exception [ 21.868400] Dumping ftrace buffer: [ 21.871925] (ftrace buffer empty) [ 21.875612] Kernel Offset: disabled [ 21.879230] Rebooting in 86400 seconds..