[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.385474] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 16.010097] random: sshd: uninitialized urandom read (32 bytes read) [ 16.230900] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 16.732472] random: sshd: uninitialized urandom read (32 bytes read) [ 16.925711] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.60' (ECDSA) to the list of known hosts. [ 22.363724] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 22.561549] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 22.569781] IP: [] l2tp_session_free+0x11c/0x200 [ 22.576200] PGD 1bf253067 [ 22.578844] PUD 1b7f5f067 PMD 0 [ 22.582333] [ 22.583982] Oops: 0002 [#1] PREEMPT SMP KASAN [ 22.588453] Dumping ftrace buffer: [ 22.591968] (ftrace buffer empty) [ 22.595656] Modules linked in: [ 22.598960] CPU: 1 PID: 3798 Comm: syz-executor227 Not tainted 4.9.118-g47b77b8 #20 [ 22.606731] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 22.616068] task: ffff8801b7740000 task.stack: ffff8801b64e0000 [ 22.622108] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 22.630958] RSP: 0018:ffff8801b64e7ca0 EFLAGS: 00010246 [ 22.636380] RAX: dffffc0000000000 RBX: ffff8801b75e4280 RCX: 0000000000000000 [ 22.643622] RDX: 1ffff10036ebc970 RSI: ffffffff836bf781 RDI: ffff8801b75e4b80 [ 22.650868] RBP: ffff8801b64e7cc0 R08: ffff8801b77408e8 R09: 0000000000000000 [ 22.658121] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b75e4a00 [ 22.665377] R13: ffff8801b75e4288 R14: 0000000000000000 R15: ffffffff83015be0 [ 22.672626] FS: 0000000001775880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 22.680834] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 22.686687] CR2: 0000000000000080 CR3: 00000001ba659000 CR4: 00000000001606f0 [ 22.693931] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 22.701174] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 22.708418] Stack: [ 22.710541] ffff8801bf36bb80 ffff8801b75e4280 ffff8801bf36bf50 ffff8801bf36be58 [ 22.718532] ffff8801b64e7ce8 ffffffff836c7092 ffff8801bf36bfc0 ffff8801bf36bb80 [ 22.726529] ffffffff836c6fc0 ffff8801b64e7d20 ffffffff830230f5 ffff8801bf36bfc0 [ 22.734519] Call Trace: [ 22.737088] [] pppol2tp_session_destruct+0xd2/0x110 [ 22.743733] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 22.750034] [] __sk_destruct+0x55/0x590 [ 22.755640] [] ? sock_release+0x1c0/0x1c0 [ 22.761414] [] sk_destruct+0x63/0x80 [ 22.766764] [] __sk_free+0x4f/0x220 [ 22.772016] [] sk_free+0x2b/0x40 [ 22.777009] [] pppol2tp_release+0x239/0x2e0 [ 22.782960] [] sock_release+0x96/0x1c0 [ 22.788472] [] sock_close+0x16/0x20 [ 22.793733] [] __fput+0x263/0x700 [ 22.798813] [] ____fput+0x15/0x20 [ 22.803895] [] task_work_run+0x10c/0x180 [ 22.809583] [] exit_to_usermode_loop+0xfc/0x120 [ 22.815880] [] do_syscall_64+0x364/0x490 [ 22.821569] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 22.828473] 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 f5 f2 c9 fd 4c 89 ea 48 b8 00 [ 22.855507] RIP [] l2tp_session_free+0x11c/0x200 [ 22.862016] RSP [ 22.865614] CR2: 0000000000000080 [ 22.869419] ---[ end trace 56aa787c76ac7a5b ]--- [ 22.874211] Kernel panic - not syncing: Fatal exception [ 22.879922] Dumping ftrace buffer: [ 22.883455] (ftrace buffer empty) [ 22.887139] Kernel Offset: disabled [ 22.890739] Rebooting in 86400 seconds..