A crafted zip with a parent-directory ("..") entry name could escape the
destination directory during extraction, writing arbitrary files on the
host (e.g. into startup/autostart folders). ExtractZipContents built the
output path by concatenating the raw zip entry name onto the destination
with no traversal check.
Changes:
- Add HasParentDirComponent() utility in Core/Util/PathUtil and use it in
GameManager::ExtractZipContents to reject entries with a ".." component.
Guard both the directory-creation and file-writing passes.
- Expose ExtractZipContents as public for testing.
- Add unittest/TestZipSlip which crafts a zip with a "../evil.txt" entry
and verifies it is not written outside the destination directory.
Henrik Rydgård