Bug 66425: Avoid exceptions found via poi-fuzz

Prevent NullPointerException

Fixes https://issues.oss-fuzz.com/issues/389724915

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1923276 13f79535-47bb-0310-9956-ffa450edef68

poi-ooxml/src/main/java/org/apache/poi/xslf/usermodel/XSLFGraphicFrame.java

@@ -84,9 +84,14 @@ public class XSLFGraphicFrame extends XSLFShape implements GraphicalFrame<XSLFSh
         }
         double x = Units.toPoints(POIXMLUnits.parseLength(off.xgetX()));
         double y = Units.toPoints(POIXMLUnits.parseLength(off.xgetY()));
+
         CTPositiveSize2D ext = xfrm.getExt();
+        if (ext == null) {
+            throw new IllegalArgumentException("Could not retrieve Ext from the XML object");
+        }
         double cx = Units.toPoints(ext.getCx());
         double cy = Units.toPoints(ext.getCy());
+
         return new Rectangle2D.Double(x, y, cx, cy);
     }
 

poi-ooxml/src/main/java/org/apache/poi/xslf/usermodel/XSLFShape.java

@@ -448,6 +448,10 @@ public abstract class XSLFShape implements Shape<XSLFShape,XSLFTextParagraph> {
         // values 1-999 refer to the index of a fill style within the fillStyleLst element
         // values 1001 and above refer to the index of a background fill style within the bgFillStyleLst element.
         long idx = fillRef.getIdx();
+
+        if (theme == null || theme.getXmlObject() == null || theme.getXmlObject().getThemeElements() == null) {
+            throw new IllegalArgumentException("Could not retrieve theme elements from shape");
+        }
         CTStyleMatrix matrix = theme.getXmlObject().getThemeElements().getFmtScheme();
         final XmlObject styleLst;
         long childIdx;