From 5ae5b869aa1be5b878957a5ec288c3dbc28900c3 Mon Sep 17 00:00:00 2001
From: Yongjun Zhang <yzhang@cloudera.com>
Date: Fri, 6 May 2016 21:50:09 -0700
Subject: [PATCH] YARN-5048. DelegationTokenRenewer#skipTokenRenewal may throw
 NPE (Jian He via Yongjun Zhang)

(cherry picked from commit 47c41e7ac7e6b905a58550f8899f629c1cf8b138)
---
 .../resourcemanager/security/DelegationTokenRenewer.java | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/security/DelegationTokenRenewer.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/security/DelegationTokenRenewer.java
index cca14e9472f..fd12f11c789 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/security/DelegationTokenRenewer.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/security/DelegationTokenRenewer.java
@@ -539,9 +539,14 @@ public class DelegationTokenRenewer extends AbstractService {
    */
   private boolean skipTokenRenewal(Token<?> token)
       throws IOException {
+
     @SuppressWarnings("unchecked")
-    Text renewer = ((Token<AbstractDelegationTokenIdentifier>)token).
-        decodeIdentifier().getRenewer();
+    AbstractDelegationTokenIdentifier identifier =
+        ((Token<AbstractDelegationTokenIdentifier>) token).decodeIdentifier();
+    if (identifier == null) {
+      return false;
+    }
+    Text renewer = identifier.getRenewer();
     return (renewer != null && renewer.toString().equals(""));
   }