--- a/jdk/src/share/classes/java/util/HashMap.java	Thu May 31 17:10:57 2012 -0400
+++ b/jdk/src/share/classes/java/util/HashMap.java	Fri Jun 01 00:05:21 2012 -0700
@@ -784,7 +784,7 @@
     void addEntry(int hash, K key, V value, int bucketIndex) {
         if ((size >= threshold) && (null != table[bucketIndex])) {
             resize(2 * table.length);
-            hash = hash(key);
+            hash = (null != key) ? hash(key) : 0;
             bucketIndex = indexFor(hash, table.length);
         }
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/java/util/HashMap/NullKeyAtResize.java	Fri Jun 01 00:05:21 2012 -0700
@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/**
+ * @test
+ * @bug 7173432
+ * @summary If the key to be inserted into a HashMap is null and the table
+ * needs to be resized as part of the insertion then addEntry will try to
+ * recalculate the hash of a null key. This will fail with an NPE.
+ */
+
+import java.util.*;
+
+public class NullKeyAtResize {
+    public static void main(String[] args) throws Exception {
+        List<Object> old_order = new ArrayList<>();
+        Map<Object,Object> m = new HashMap<>(16);
+        int number = 0;
+        while(number < 100000) {
+            m.put(null,null); // try to put in null. This may cause resize.
+            m.remove(null); // remove it.
+            Integer adding = (number += 100);
+            m.put(adding, null); // try to put in a number. This wont cause resize.
+            List<Object> new_order = new ArrayList<>();
+            new_order.addAll(m.keySet());
+            new_order.remove(adding);
+            if(!old_order.equals(new_order)) {
+                // we resized and didn't crash.
+                System.out.println("Encountered resize after " + (number / 100) + " iterations");
+                break;
+            }
+            // remember this order for the next time around.
+            old_order.clear();
+            old_order.addAll(m.keySet());
+        }
+        if(number == 100000) {
+            throw new Error("Resize never occurred");
+        }
+    }
+}