Describe CVE-2021-47404.
What is CVE-2021-47404?
In the Linux kernel, the following vulnerability has been resolved:

HID: betop: fix slab-out-of-bounds Write in betop_probe

Syzbot reported slab-out-of-bounds Write bug in hid-betopff driver.
The problem is the driver assumes the device must have an input report but
some malicious devices violate this assumption.

So this patch checks hid_device's input is non empty before it's been used..