The archive backend passes remote .sqfs bytes straight to the go-diskfs squashfs
parser, which does not validate several attacker-controlled superblock and
metadata fields. A crafted image can make the parser panic.
Recover panics at the go-diskfs boundary and return an "invalid or corrupt
squashfs image" error instead. As well as the parse entry points (Read, ReadDir,
OpenFile) this wraps the reader returned by Open, since the parser reads file
data lazily and can panic long after the image opened successfully.
Addresses GHSA-6jcg-q3wp-x2f4.
Nick Craig-Wood
31f3856281