Add index data size validation

src/main/java/org/verapdf/pd/font/cff/CFFFileBaseParser.java

@@ -34,6 +34,8 @@
  */
 class CFFFileBaseParser {
 
+    private static final long MAX_INDEX_DATA_SIZE = 100_000_000;
+
     protected SeekableInputStream source;
     protected CFFIndex definedNames;
 
@@ -73,15 +75,22 @@ protected CFFIndex readIndex() throws IOException {
             return new CFFIndex(0, 0, new int[0], new byte[0]);
         }
         int offSize = readCard8();
-        if (offSize == 0) {
-            throw new IOException("Bad offset size");
+        if (offSize < 1 || offSize > 4) {
+            throw new IOException("Bad offset size " + offSize);
         }
         int[] offset = new int[count + 1];
         for (int i = 0; i < count + 1; ++i) {
             offset[i] = (int) readOffset(offSize);
         }
         if (offset[count] < 1) {
-            throw new IOException("Wrong index data offset");
+            throw new IOException("Wrong index data offset " + offset[count]);
+        }
+        long dataSize = offset[count] - 1L;
+        if (dataSize > MAX_INDEX_DATA_SIZE) {
+            throw new IOException("Index data size exceeds maximum allowed size");
+        }
+        if (dataSize > source.getStreamLength() - source.getOffset()) {
+            throw new IOException("Index data size exceeds remaining stream length");
         }
         byte[] data = new byte[offset[count] - 1];
         if (data.length != 0 && source.read(data, data.length) != data.length) {

src/test/java/org/verapdf/pd/font/cff/CFFFileBaseParserTest.java

@@ -0,0 +1,62 @@
+/*
+ * This file is part of veraPDF Parser, a module of the veraPDF project.
+ * Copyright (c) 2015-2026, veraPDF Consortium <info@verapdf.org>
+ * All rights reserved.
+ *
+ * veraPDF Parser is free software: you can redistribute it and/or modify
+ * it under the terms of either:
+ *
+ * The GNU General public license GPLv3+.
+ * You should have received a copy of the GNU General Public License
+ * along with veraPDF Parser as the LICENSE.GPL file in the root of the source
+ * tree.  If not, see http://www.gnu.org/licenses/ or
+ * https://www.gnu.org/licenses/gpl-3.0.en.html.
+ *
+ * The Mozilla Public License MPLv2+.
+ * You should have received a copy of the Mozilla Public License along with
+ * veraPDF Parser as the LICENSE.MPL file in the root of the source tree.
+ * If a copy of the MPL was not distributed with this file, you can obtain one at
+ * http://mozilla.org/MPL/2.0/.
+ */
+package org.verapdf.pd.font.cff;
+
+import org.junit.Test;
+import org.verapdf.as.io.ASMemoryInStream;
+import org.verapdf.io.SeekableInputStream;
+
+import java.io.IOException;
+
+import static org.junit.Assert.assertEquals;
+
+public class CFFFileBaseParserTest {
+
+    private static CFFFileBaseParser parser(int... bytes) throws IOException {
+        byte[] data = new byte[bytes.length];
+        for (int i = 0; i < bytes.length; ++i) {
+            data[i] = (byte) bytes[i];
+        }
+        return new CFFFileBaseParser(SeekableInputStream.getSeekableStream(new ASMemoryInStream(data)));
+    }
+
+    @Test(expected = IOException.class)
+    public void testReadIndexWithOversizedLastOffset() throws IOException {
+        parser(0x00, 0x01, 0x04, 0x00, 0x00, 0x00, 0x01, 0x3F, 0xFF, 0xFF, 0xFF).readIndex();
+    }
+
+    @Test(expected = IOException.class)
+    public void testReadIndexWithNegativeLastOffset() throws IOException {
+        parser(0x00, 0x01, 0x04, 0x00, 0x00, 0x00, 0x01, 0xFF, 0xFF, 0xFF, 0xFF).readIndex();
+    }
+
+    @Test(expected = IOException.class)
+    public void testReadIndexWithOversizedOffSize() throws IOException {
+        parser(0x00, 0x01, 0x05, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x04).readIndex();
+    }
+
+    @Test
+    public void testReadValidIndex() throws IOException {
+        CFFIndex index = parser(0x00, 0x01, 0x01, 0x01, 0x04, 'a', 'b', 'c').readIndex();
+        assertEquals(1, index.size());
+        assertEquals(3, index.getDataLength());
+    }
+}