CVE-2021-47348: Improper Restriction of Operations within the Bounds of a Memory Buffer

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

drm/amd/display: Avoid HDCP over-read and corruption

Instead of reading the desired 5 bytes of the actual target field, the code was reading 8. This could result in a corrupted value if the trailing 3 bytes were non-zero, so instead use an appropriately sized and zero-initialized bounce buffer, and read only 5 bytes before casting to u64.