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=61259

Also fix handling of NullPointerException

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1911517 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 6 insertions, 1 deletions

diff --git a/poi-scratchpad/src/main/java/org/apache/poi/hslf/usermodel/HSLFSlideShowImpl.java b/poi-scratchpad/src/main/java/org/apache/poi/hslf/usermodel/HSLFSlideShowImpl.java
index 54edf47faa..70fb287026 100644
--- a/poi-scratchpad/src/main/java/org/apache/poi/hslf/usermodel/HSLFSlideShowImpl.java
+++ b/poi-scratchpad/src/main/java/org/apache/poi/hslf/usermodel/HSLFSlideShowImpl.java
@@ -72,6 +72,7 @@ import org.apache.poi.poifs.crypt.EncryptionInfo;
 import org.apache.poi.poifs.filesystem.DirectoryNode;
 import org.apache.poi.poifs.filesystem.DocumentEntry;
 import org.apache.poi.poifs.filesystem.DocumentInputStream;
+import org.apache.poi.poifs.filesystem.Entry;
 import org.apache.poi.poifs.filesystem.EntryUtils;
 import org.apache.poi.poifs.filesystem.POIFSFileSystem;
 import org.apache.poi.sl.usermodel.PictureData;
@@ -229,7 +230,11 @@ public final class HSLFSlideShowImpl extends POIDocument implements Closeable {
         }
 
         // Get the main document stream
-        DocumentEntry docProps = (DocumentEntry)dir.getEntry(POWERPOINT_DOCUMENT);
+        final Entry entry = dir.getEntry(POWERPOINT_DOCUMENT);
+        if (!(entry instanceof DocumentEntry)) {
+            throw new IllegalArgumentException("Had unexpected type of entry for name: " + POWERPOINT_DOCUMENT + ": " + entry.getClass());
+        }
+        DocumentEntry docProps = (DocumentEntry) entry;
 
         // Grab the document stream
         int len = docProps.getSize();