fix: prevent StackOverflowError when parsing deeply nested KML containers and multi-geometries

library/src/main/java/com/google/maps/android/data/kml/KmlContainerParser.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2020 Google Inc.
+ * Copyright 2026 Google LLC
  * 
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -61,10 +61,12 @@
      * XmlPullParser) and assigns specific elements read from the XmlPullParser to the container.
      */
 
+    /* package */ static final int MAX_CONTAINER_DEPTH = 20;
+
     /* package */
     static KmlContainer createContainer(XmlPullParser parser)
             throws XmlPullParserException, IOException {
-        return assignPropertiesToContainer(parser);
+        return assignPropertiesToContainer(parser, MAX_CONTAINER_DEPTH);
     }
 
     /**
@@ -74,8 +76,12 @@ static KmlContainer createContainer(XmlPullParser parser)
      * @param parser XmlPullParser object reading from a KML file
      * @return KmlContainer object with properties read from the XmlPullParser
      */
-    private static KmlContainer assignPropertiesToContainer(XmlPullParser parser)
+    /* package */ static KmlContainer assignPropertiesToContainer(XmlPullParser parser, int maxDepth)
             throws XmlPullParserException, IOException {
+        if (maxDepth < 0) {
+            KmlParser.skip(parser);
+            return null;
+        }
         String startTag = parser.getName();
         String containerId = null;
         HashMap<String, String> containerProperties = new HashMap<String, String>();
@@ -97,7 +103,10 @@ private static KmlContainer assignPropertiesToContainer(XmlPullParser parser)
                 if (parser.getName().matches(UNSUPPORTED_REGEX)) {
                     KmlParser.skip(parser);
                 } else if (parser.getName().matches(CONTAINER_REGEX)) {
-                    nestedContainers.add(assignPropertiesToContainer(parser));
+                    KmlContainer container = assignPropertiesToContainer(parser, maxDepth - 1);
+                    if (container != null) {
+                        nestedContainers.add(container);
+                    }
                 } else if (parser.getName().matches(PROPERTY_REGEX)) {
                     containerProperties.put(parser.getName(), parser.nextText());
                 } else if (parser.getName().equals(STYLE_MAP)) {

library/src/main/java/com/google/maps/android/data/kml/KmlFeatureParser.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2020 Google Inc.
+ * Copyright 2026 Google LLC
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -182,8 +182,19 @@ private static String getImageUrl(XmlPullParser parser)
      *
      * @param geometryType Type of geometry object to create
      */
-    private static Geometry createGeometry(XmlPullParser parser, String geometryType)
+    /* package */ static final int MAX_GEOMETRY_DEPTH = 20;
+
+    /* package */ static Geometry createGeometry(XmlPullParser parser, String geometryType)
+            throws IOException, XmlPullParserException {
+        return createGeometry(parser, geometryType, MAX_GEOMETRY_DEPTH);
+    }
+
+    /* package */ static Geometry createGeometry(XmlPullParser parser, String geometryType, int maxDepth)
             throws IOException, XmlPullParserException {
+        if (maxDepth < 0) {
+            KmlParser.skip(parser);
+            return null;
+        }
         int eventType = parser.getEventType();
         while (!(eventType == END_TAG && parser.getName().equals(geometryType))) {
             if (eventType == START_TAG) {
@@ -196,7 +207,7 @@ private static Geometry createGeometry(XmlPullParser parser, String geometryType
                 } else if (parser.getName().equals("Polygon")) {
                     return createPolygon(parser);
                 } else if (parser.getName().equals("MultiGeometry")) {
-                    return createMultiGeometry(parser);
+                    return createMultiGeometry(parser, maxDepth);
                 } else if (parser.getName().equals("MultiTrack")) {
                     return createMultiTrack(parser);
                 }
@@ -349,14 +360,17 @@ private static KmlPolygon createPolygon(XmlPullParser parser)
      *
      * @return KmlMultiGeometry object
      */
-    private static KmlMultiGeometry createMultiGeometry(XmlPullParser parser)
+    private static KmlMultiGeometry createMultiGeometry(XmlPullParser parser, int maxDepth)
             throws XmlPullParserException, IOException {
         ArrayList<Geometry> geometries = new ArrayList<Geometry>();
         // Get next otherwise have an infinite loop
         int eventType = parser.next();
         while (!(eventType == END_TAG && parser.getName().equals("MultiGeometry"))) {
             if (eventType == START_TAG && parser.getName().matches(GEOMETRY_REGEX)) {
-                geometries.add(createGeometry(parser, parser.getName()));
+                Geometry geom = createGeometry(parser, parser.getName(), maxDepth - 1);
+                if (geom != null) {
+                    geometries.add(geom);
+                }
             }
             eventType = parser.next();
         }

library/src/test/java/com/google/maps/android/data/kml/KmlFeatureParserTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2020 Google Inc.
+ * Copyright 2026 Google LLC
  * 
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -125,4 +125,52 @@ public void testSuitableCoordinates() throws Exception {
         assertEquals(latLng.latitude, -43.60505741890396, 0.001);
         assertEquals(latLng.longitude, 170.1435558771009, 0.001);
     }
+
+    @Test
+    public void testDeeplyNestedMultiGeometry_doesNotThrowStackOverflow() throws Exception {
+        StringBuilder sb = new StringBuilder("<Placemark>");
+        for (int i = 0; i < 200; i++) {
+            sb.append("<MultiGeometry>");
+        }
+        sb.append("<Point><coordinates>0,0</coordinates></Point>");
+        for (int i = 0; i < 200; i++) {
+            sb.append("</MultiGeometry>");
+        }
+        sb.append("</Placemark>");
+        XmlPullParser parser = KmlTestUtil.createParserFromString(sb.toString());
+        parser.next();
+        KmlPlacemark placemark = KmlFeatureParser.createPlacemark(parser);
+        assertNotNull(placemark);
+    }
+
+    @Test
+    public void testGeometryExceedingMaxDepth_returnsNull() throws Exception {
+        XmlPullParser parser = KmlTestUtil.createParserFromString("<Point><coordinates>0,0</coordinates></Point>");
+        parser.next();
+        assertNull(KmlFeatureParser.createGeometry(parser, "Point", -1));
+    }
+
+    @Test
+    public void testDeeplyNestedFolder_doesNotThrowStackOverflow() throws Exception {
+        StringBuilder sb = new StringBuilder("<Folder>");
+        for (int i = 0; i < 200; i++) {
+            sb.append("<Folder>");
+        }
+        sb.append("<name>Deep Folder</name>");
+        for (int i = 0; i < 200; i++) {
+            sb.append("</Folder>");
+        }
+        sb.append("</Folder>");
+        XmlPullParser parser = KmlTestUtil.createParserFromString(sb.toString());
+        parser.next();
+        KmlContainer container = KmlContainerParser.assignPropertiesToContainer(parser, 20);
+        assertNotNull(container);
+    }
+
+    @Test
+    public void testContainerExceedingMaxDepth_returnsNull() throws Exception {
+        XmlPullParser parser = KmlTestUtil.createParserFromString("<Folder><name>Test</name></Folder>");
+        parser.next();
+        assertNull(KmlContainerParser.assignPropertiesToContainer(parser, -1));
+    }
 }

library/src/test/java/com/google/maps/android/data/kml/KmlTestUtil.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2020 Google Inc.
+ * Copyright 2026 Google LLC
  * 
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -43,4 +43,14 @@ static XmlPullParser createParser(String fileName) throws XmlPullParserException
         parser.setInput(stream, null);
         return parser;
     }
+
+    static XmlPullParser createParserFromString(String xml) throws XmlPullParserException, IOException {
+        XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
+        factory.setFeature(XmlPullParser.FEATURE_PROCESS_DOCDECL, false);
+        factory.setFeature(XmlPullParser.FEATURE_VALIDATION, false);
+        factory.setNamespaceAware(true);
+        XmlPullParser parser = factory.newPullParser();
+        parser.setInput(new java.io.StringReader(xml));
+        return parser;
+    }
 }