fix: propagate non-EOF errors out of safeCopy (#4807)

Signed-off-by: SAY-5 <SAY-5@users.noreply.github.com>

internal/file/copy.go

@@ -12,8 +12,20 @@ const perFileReadLimit = 2 * GB
 // protect against decompression bomb attacks.
 func safeCopy(writer io.Writer, reader io.Reader) error {
 	numBytes, err := io.Copy(writer, io.LimitReader(reader, perFileReadLimit))
-	if numBytes >= perFileReadLimit || errors.Is(err, io.EOF) {
+	if numBytes >= perFileReadLimit {
 		return fmt.Errorf("zip read limit hit (potential decompression bomb attack)")
 	}
+	// Propagate decompression / read errors up to the caller. io.Copy
+	// on the happy path returns (n, nil); the only way err is non-nil
+	// here is that the underlying reader surfaced a real failure
+	// ("flate: corrupt input before offset X" on a mangled ZIP entry,
+	// a network-backed reader erroring mid-stream, etc.). The previous
+	// implementation dropped that error and the caller stored a
+	// partial / empty buffer as a "successful" extract, which silently
+	// downgraded Java cataloger output and caused SBOM scanners to
+	// miss known CVEs (#4806).
+	if err != nil && !errors.Is(err, io.EOF) {
+		return fmt.Errorf("failed to read archive entry: %w", err)
+	}
 	return nil
 }