--- a/jdk/src/share/classes/com/sun/security/sasl/digest/DigestMD5Client.java	Thu May 02 14:26:51 2013 -0700
+++ b/jdk/src/share/classes/com/sun/security/sasl/digest/DigestMD5Client.java	Fri May 03 10:43:24 2013 +0800
@@ -348,14 +348,23 @@
                     0, false);
                 cbh.handle(new Callback[] {ccb, ncb, pcb});
 
-                /* Acquire realm from RealmChoiceCallback*/
-                negotiatedRealm = realmTokens[ccb.getSelectedIndexes()[0]];
+                // Acquire realm from RealmChoiceCallback
+                int[] selected = ccb.getSelectedIndexes();
+                if (selected == null
+                        || selected[0] < 0
+                        || selected[0] >= realmTokens.length) {
+                    throw new SaslException("DIGEST-MD5: Invalid realm chosen");
+                }
+                negotiatedRealm = realmTokens[selected[0]];
             }
 
             passwd = pcb.getPassword();
             pcb.clearPassword();
             username = ncb.getName();
 
+        } catch (SaslException se) {
+            throw se;
+
         } catch (UnsupportedCallbackException e) {
             throw new SaslException("DIGEST-MD5: Cannot perform callback to " +
                 "acquire realm, authentication ID or password", e);

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/com/sun/security/sasl/digest/AuthRealmChoices.java	Fri May 03 10:43:24 2013 +0800
@@ -0,0 +1,92 @@
+/*
+ * Copyright (c) 2013, 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 8013855
+ * @run main AuthRealmChoices 1
+ * @run main AuthRealmChoices 2
+ * @summary DigestMD5Client has not checked RealmChoiceCallback value
+ */
+
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+import javax.security.auth.callback.Callback;
+import javax.security.auth.callback.CallbackHandler;
+import javax.security.auth.callback.UnsupportedCallbackException;
+import javax.security.sasl.*;
+
+public class AuthRealmChoices {
+    private static final String MECH = "DIGEST-MD5";
+    private static final String SERVER_FQDN = "machineX.imc.org";
+    private static final String PROTOCOL = "jmx";
+
+    private static final byte[] EMPTY = new byte[0];
+
+    public static void main(String[] args) throws Exception {
+
+        Map props = new HashMap();
+        props.put("com.sun.security.sasl.digest.realm",
+            "IMC.ORG foo.bar machineX");
+
+        SaslClient clnt = Sasl.createSaslClient(
+            new String[]{MECH}, null, PROTOCOL, SERVER_FQDN, null,
+                new CallbackHandler() {
+                    @Override
+                    public void handle(Callback[] callbacks)
+                            throws IOException, UnsupportedCallbackException {
+                        for (Callback cb: callbacks) {
+                            if (cb instanceof RealmChoiceCallback) {
+                                // Two tests:
+                                // 1. Set an index out of bound
+                                // 2. No index set at all
+                                if (args[0].equals("1")) {
+                                    ((RealmChoiceCallback)cb).setSelectedIndex(10);
+                                }
+                            }
+                        }
+                    }
+                });
+
+        SaslServer srv = Sasl.createSaslServer(MECH, PROTOCOL, SERVER_FQDN, props,
+            new CallbackHandler() {
+                @Override
+                public void handle(Callback[] callbacks)
+                        throws IOException, UnsupportedCallbackException {
+                    for (Callback cb: callbacks) {
+                        System.out.println(cb);
+                    }
+                }
+            });
+
+        byte[] challenge = srv.evaluateResponse(EMPTY);
+
+        try {
+            clnt.evaluateChallenge(challenge);
+            throw new Exception();
+        } catch (SaslException se) {
+            System.out.println(se);
+        }
+    }
+}