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=61162

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1911459 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 6 insertions, 1 deletions

diff --git a/poi-scratchpad/src/main/java/org/apache/poi/hpbf/model/HPBFPart.java b/poi-scratchpad/src/main/java/org/apache/poi/hpbf/model/HPBFPart.java
index a723fc2cc1..c3d44099de 100644
--- a/poi-scratchpad/src/main/java/org/apache/poi/hpbf/model/HPBFPart.java
+++ b/poi-scratchpad/src/main/java/org/apache/poi/hpbf/model/HPBFPart.java
@@ -23,6 +23,7 @@ import java.io.InputStream;
 
 import org.apache.commons.io.input.UnsynchronizedByteArrayInputStream;
 import org.apache.poi.poifs.filesystem.DirectoryNode;
+import org.apache.poi.poifs.filesystem.Entry;
 import org.apache.poi.util.IOUtils;
 
 /**
@@ -57,7 +58,11 @@ public abstract class HPBFPart {
         DirectoryNode dir = baseDir;
         for(int i=0; i<path.length-1; i++) {
             try {
-                dir = (DirectoryNode)dir.getEntry(path[i]);
+                Entry entry = dir.getEntry(path[i]);
+                if (!(entry instanceof DirectoryNode)) {
+                    throw new IllegalArgumentException("Had unexpected type of entry for path: " + path[i] + ": " + entry);
+                }
+                dir = (DirectoryNode) entry;
             } catch (FileNotFoundException e) {
                 throw new IllegalArgumentException("File invalid - failed to find directory entry '"
                         + path[i] + "': " + e);