--- xnu/xnu-344.49/iokit/Kernel/IOMultiMemoryDescriptor.cpp
+++ xnu/xnu-792.2.4/iokit/Kernel/IOMultiMemoryDescriptor.cpp
@@ -3,22 +3,19 @@
  *
  * @APPLE_LICENSE_HEADER_START@
  * 
- * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
+ * The contents of this file constitute Original Code as defined in and
+ * are subject to the Apple Public Source License Version 1.1 (the
+ * "License").  You may not use this file except in compliance with the
+ * License.  Please obtain a copy of the License at
+ * http://www.apple.com/publicsource and read it before using this file.
  * 
- * This file contains Original Code and/or Modifications of Original Code
- * as defined in and that are subject to the Apple Public Source License
- * Version 2.0 (the 'License'). You may not use this file except in
- * compliance with the License. Please obtain a copy of the License at
- * http://www.opensource.apple.com/apsl/ and read it before using this
- * file.
- * 
- * The Original Code and all software distributed under the License are
- * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * This Original Code and all software distributed under the License are
+ * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
- * Please see the License for the specific language governing rights and
- * limitations under the License.
+ * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
+ * License for the specific language governing rights and limitations
+ * under the License.
  * 
  * @APPLE_LICENSE_HEADER_END@
  */
@@ -90,7 +87,7 @@
                                   IOMemoryDescriptor ** descriptors,
                                   UInt32                withCount,
                                   IODirection           withDirection,
-                                  bool                  asReference = false )
+                                  bool                  asReference )
 {
     //
     // Create a new IOMultiMemoryDescriptor.  The "buffer" is made up of several
@@ -121,7 +118,7 @@
                                   IOMemoryDescriptor ** descriptors,
                                   UInt32                withCount,
                                   IODirection           withDirection,
-                                  bool                  asReference = false )
+                                  bool                  asReference )
 {
     //
     // Initialize an IOMultiMemoryDescriptor. The "buffer" is made up of several
@@ -134,10 +131,19 @@
     assert(descriptors);
     assert(withCount);
 
-    // Ask our superclass' opinion.
-
-    if ( super::init() == false )  return false;
-
+    // Release existing descriptors, if any
+    if ( _descriptors )
+    {
+        for ( unsigned index = 0; index < _descriptorsCount; index++ ) 
+            _descriptors[index]->release();
+
+        if ( _descriptorsIsAllocated )
+            IODelete(_descriptors, IOMemoryDescriptor *, _descriptorsCount);
+    } else {
+        // Ask our superclass' opinion.
+        if ( super::init() == false )  return false;
+    }
+    
     // Initialize our minimal state.
 
     _descriptors            = 0;