Bug 66425: Avoid a ClassCastException found via oss-fuzz

We try to avoid throwing ClassCastException, but it was possible to trigger one here with a specially crafted input-file Should fix https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=62170 git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1912252 13f79535-47bb-0310-9956-ffa450edef68
apache · Sep 11, 2023 · 481c00b · 481c00b
1 parent e666d37
commit 481c00b
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Showing 4 changed files with 8 additions and 4 deletions.
diff --git a/poi-ooxml/src/main/java/org/apache/poi/xslf/usermodel/XSLFSheet.java b/poi-ooxml/src/main/java/org/apache/poi/xslf/usermodel/XSLFSheet.java
@@ -395,7 +395,11 @@ protected CTGroupShape getSpTree(){
             if(sp.length == 0) {
                 throw new IllegalStateException("CTGroupShape was not found");
             }
-            _spTree = (CTGroupShape)sp[0];
+            XmlObject xmlObject = sp[0];
+            if (!(xmlObject instanceof CTGroupShape)) {
+                throw new IllegalArgumentException("Had unexpected type of entry: " + xmlObject.getClass());
+            }
+            _spTree = (CTGroupShape) xmlObject;
         }
         return _spTree;
     }

diff --git a/poi-ooxml/src/main/java/org/apache/poi/xslf/usermodel/XSLFSlide.java b/poi-ooxml/src/main/java/org/apache/poi/xslf/usermodel/XSLFSlide.java
@@ -271,9 +271,9 @@ public XSLFTheme getTheme(){
      */
     @Override
     public XSLFBackground getBackground() {
-        CTBackground bg = _slide.getCSld().getBg();
-        if(bg != null) {
-            return new XSLFBackground(bg, this);
+        if(_slide.getCSld() != null &&
+                _slide.getCSld().getBg() != null) {
+            return new XSLFBackground(_slide.getCSld().getBg(), this);
         } else {
             return getMasterSheet().getBackground();
         }

diff --git a/test-data/slideshow/clusterfuzz-testcase-minimized-POIXSLFFuzzer-5463285576892416.pptx b/test-data/slideshow/clusterfuzz-testcase-minimized-POIXSLFFuzzer-5463285576892416.pptx
diff --git a/test-data/spreadsheet/stress.xls b/test-data/spreadsheet/stress.xls