fix: prevent panic on malformed ISO9660 path table

iso9660/iso9660.go

@@ -198,15 +198,16 @@ func (iso *ISO9660) parsePathTable() error {
 	iso.pathTable = nil
 	i := 0
 	for i < len(pathTableRaw) {
-		if i >= len(pathTableRaw) {
-			break
-		}
-
 		dirNameLen := int(pathTableRaw[i])
 		if dirNameLen == 0 {
 			break
 		}
 
+		// Validate we have enough data for this entry (8 byte header + name)
+		if i+8+dirNameLen > len(pathTableRaw) {
+			return fmt.Errorf("truncated path table entry at offset %d", i)
+		}
+
 		// Extended attribute record length at i+1 (skip)
 		dirLBA := binary.LittleEndian.Uint32(pathTableRaw[i+2 : i+6])
 		dirParentIdx := int(binary.LittleEndian.Uint16(pathTableRaw[i+6:i+8])) - 1

iso9660/iso9660_test.go

@@ -545,3 +545,40 @@ func TestGetDataPreparerID(t *testing.T) {
 	// Data preparer ID is at a different offset - our minimal ISO doesn't set it
 	_ = iso.GetDataPreparerID()
 }
+
+// TestISO9660_TruncatedPathTable verifies bounds check for malformed path table entries.
+func TestISO9660_TruncatedPathTable(t *testing.T) {
+	t.Parallel()
+
+	tmpDir := t.TempDir()
+
+	// Create a minimal ISO
+	isoData := createMinimalISO("VOL", "SYS", "PUB")
+
+	// Corrupt the path table: set a directory name length that exceeds the path table size
+	// Path table is at block 18 (offset 18 * 2048 = 36864)
+	pathTableOffset := 18 * 2048
+
+	// Set directory name length to a large value (e.g., 100) that exceeds remaining data
+	// The path table entry format is:
+	// - byte 0: directory name length
+	// - byte 1: extended attribute record length
+	// - bytes 2-5: directory LBA (little-endian)
+	// - bytes 6-7: parent directory number (little-endian)
+	// - bytes 8+: directory name
+	isoData[pathTableOffset] = 100 // Large name length that would overflow
+
+	isoPath := filepath.Join(tmpDir, "truncated.iso")
+	if err := os.WriteFile(isoPath, isoData, 0o600); err != nil {
+		t.Fatalf("Failed to write ISO: %v", err)
+	}
+
+	// This should fail with a truncated path table error, not panic
+	_, err := Open(isoPath)
+	if err == nil {
+		t.Error("Open() should error for truncated path table entry")
+	}
+	if !strings.Contains(err.Error(), "truncated path table entry") {
+		t.Errorf("Open() error = %v, want error containing 'truncated path table entry'", err)
+	}
+}