CVE-2021-47604

In the Linux kernel, the following vulnerability has been resolved:

vduse: check that offset is within bounds in get_config()

This condition checks "len" but it does not check "offset" and that

could result in an out of bounds read if "offset > dev->config_size".

The problem is that since both variables are unsigned the

"dev->config_size - offset" subtraction would result in a very high

unsigned value.

I think these checks might not be necessary because "len" and "offset"

are supposed to already have been validated using the

vhost_vdpa_config_validate() function. But I do not know the code

perfectly, and I like to be safe.