Fix EnumerableViewOfDispatch.GetEnumerator ref counting (dotnet#34230)

Qdigital · Mar 30, 2020 · b95caba · b95caba
1 parent 8511b5b
commit b95caba
Showing 1 changed file with 16 additions and 4 deletions.
diff --git a/...e.CoreLib/src/System/Runtime/InteropServices/CustomMarshalers/EnumerableViewOfDispatch.cs b/...e.CoreLib/src/System/Runtime/InteropServices/CustomMarshalers/EnumerableViewOfDispatch.cs
@@ -40,13 +40,25 @@ public IEnumerator GetEnumerator()
                     IntPtr.Zero);
             }
 
-            object? resultAsObject = result.ToObject();
-            if (!(resultAsObject is IEnumVARIANT enumVariant))
+            IntPtr enumVariantPtr = IntPtr.Zero;
+            try
             {
-                throw new InvalidOperationException(SR.InvalidOp_InvalidNewEnumVariant);
+                object? resultAsObject = result.ToObject();
+                if (!(resultAsObject is IEnumVARIANT enumVariant))
+                {
+                    throw new InvalidOperationException(SR.InvalidOp_InvalidNewEnumVariant);
+                }
+
+                enumVariantPtr = Marshal.GetIUnknownForObject(enumVariant);
+                return (IEnumerator)EnumeratorToEnumVariantMarshaler.GetInstance(null).MarshalNativeToManaged(enumVariantPtr);
             }
+            finally
+            {
+                result.Clear();
 
-            return (IEnumerator)EnumeratorToEnumVariantMarshaler.GetInstance(null).MarshalNativeToManaged(Marshal.GetIUnknownForObject(enumVariant));
+                if (enumVariantPtr != IntPtr.Zero)
+                    Marshal.Release(enumVariantPtr);
+            }
         }
 
         public object GetUnderlyingObject()