diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index 7b25112e2c..a14099e39a 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -444,6 +444,9 @@ Release 2.0.0 - UNRELEASED
     HDFS-3369. Rename {get|set|add}INode(..) methods in BlockManager and
     BlocksMap to {get|set|add}BlockCollection(..).  (John George via szetszwo)
 
+    HDFS-3134. harden edit log loader against malformed or malicious input.
+    (Colin Patrick McCabe via eli)
+
   OPTIMIZATIONS
 
     HDFS-3024. Improve performance of stringification in addStoredBlock (todd)
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/security/token/block/BlockTokenIdentifier.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/security/token/block/BlockTokenIdentifier.java
index c1fd3f9f82..62f2d76237 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/security/token/block/BlockTokenIdentifier.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/security/token/block/BlockTokenIdentifier.java
@@ -148,7 +148,8 @@ public void readFields(DataInput in) throws IOException {
     userId = WritableUtils.readString(in);
     blockPoolId = WritableUtils.readString(in);
     blockId = WritableUtils.readVLong(in);
-    int length = WritableUtils.readVInt(in);
+    int length = WritableUtils.readVIntInRange(in, 0,
+        AccessMode.class.getEnumConstants().length);
     for (int i = 0; i < length; i++) {
       modes.add(WritableUtils.readEnum(in, AccessMode.class));
     }
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSEditLogOp.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSEditLogOp.java
index 56a610f101..9f7742cc67 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSEditLogOp.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSEditLogOp.java
@@ -203,6 +203,10 @@ <T extends AddCloseOp> T setBlockSize(long blockSize) {
     }
 
     <T extends AddCloseOp> T setBlocks(Block[] blocks) {
+      if (blocks.length > MAX_BLOCKS) {
+        throw new RuntimeException("Can't have more than " + MAX_BLOCKS +
+            " in an AddCloseOp.");
+      }
       this.blocks = blocks;
       return (T)this;
     }
@@ -296,10 +300,18 @@ void readFields(DataInputStream in, int logVersion)
       }
     }
 
+    static final public int MAX_BLOCKS = 1024 * 1024 * 64;
+    
     private static Block[] readBlocks(
         DataInputStream in,
         int logVersion) throws IOException {
       int numBlocks = in.readInt();
+      if (numBlocks < 0) {
+        throw new IOException("invalid negative number of blocks");
+      } else if (numBlocks > MAX_BLOCKS) {
+        throw new IOException("invalid number of blocks: " + numBlocks +
+            ".  The maximum number of blocks per file is " + MAX_BLOCKS);
+      }
       Block[] blocks = new Block[numBlocks];
       for (int i = 0; i < numBlocks; i++) {
         Block blk = new Block();
@@ -579,6 +591,7 @@ static class ConcatDeleteOp extends FSEditLogOp {
     String trg;
     String[] srcs;
     long timestamp;
+    final static public int MAX_CONCAT_SRC = 1024 * 1024;
 
     private ConcatDeleteOp() {
       super(OP_CONCAT_DELETE);
@@ -594,7 +607,12 @@ ConcatDeleteOp setTarget(String trg) {
     }
 
     ConcatDeleteOp setSources(String[] srcs) {
+      if (srcs.length > MAX_CONCAT_SRC) {
+        throw new RuntimeException("ConcatDeleteOp can only have " +
+            MAX_CONCAT_SRC + " sources at most.");
+      }
       this.srcs = srcs;
+
       return this;
     }
 
@@ -624,8 +642,8 @@ void readFields(DataInputStream in, int logVersion)
       if (!LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
         this.length = in.readInt();
         if (length < 3) { // trg, srcs.., timestamp
-          throw new IOException("Incorrect data format. "
-              + "Concat delete operation.");
+          throw new IOException("Incorrect data format " +
+              "for ConcatDeleteOp.");
         }
       }
       this.trg = FSImageSerialization.readString(in);
@@ -635,6 +653,15 @@ void readFields(DataInputStream in, int logVersion)
       } else {
         srcSize = this.length - 1 - 1; // trg and timestamp
       }
+      if (srcSize < 0) {
+          throw new IOException("Incorrect data format. "
+              + "ConcatDeleteOp cannot have a negative number of data " +
+              " sources.");
+      } else if (srcSize > MAX_CONCAT_SRC) {
+          throw new IOException("Incorrect data format. "
+              + "ConcatDeleteOp can have at most " + MAX_CONCAT_SRC +
+              " sources, but we tried to have " + (length - 3) + " sources.");
+      }
       this.srcs = new String [srcSize];
       for(int i=0; i<srcSize;i++) {
         srcs[i]= FSImageSerialization.readString(in);
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestEditLog.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestEditLog.java
index 7f4872198b..d1136bc21d 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestEditLog.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestEditLog.java
@@ -29,6 +29,7 @@
 import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
+import java.util.Random;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -1155,4 +1156,75 @@ public boolean accept(File dir, String name) {
           "No non-corrupt logs for txid " + startGapTxId, ioe);
     }
   }
+
+  /**
+   * Test that we can read from a byte stream without crashing.
+   *
+   */
+  static void validateNoCrash(byte garbage[]) throws IOException {
+    final String TEST_LOG_NAME = "test_edit_log";
+
+    EditLogFileOutputStream elfos = null;
+    File file = null;
+    EditLogFileInputStream elfis = null;
+    try {
+      file = new File(TEST_LOG_NAME);
+      elfos = new EditLogFileOutputStream(file, 0);
+      elfos.create();
+      elfos.writeRaw(garbage, 0, garbage.length);
+      elfos.setReadyToFlush();
+      elfos.flushAndSync();
+      elfos.close();
+      elfos = null;
+      file = new File(TEST_LOG_NAME);
+      elfis = new EditLogFileInputStream(file);
+
+      // verify that we can read everything without killing the JVM or
+      // throwing an exception other than IOException
+      try {
+        while (true) {
+          FSEditLogOp op = elfis.readOp();
+          if (op == null)
+            break;
+        }
+      } catch (IOException e) {
+      } catch (Throwable t) {
+        StringWriter sw = new StringWriter();
+        t.printStackTrace(new PrintWriter(sw));
+        fail("caught non-IOException throwable with message " +
+            t.getMessage() + "\nstack trace\n" + sw.toString());
+      }
+    } finally {
+      if ((elfos != null) && (elfos.isOpen()))
+        elfos.close();
+      if (elfis != null)
+        elfis.close();
+    }
+  }
+
+  static byte[][] invalidSequenecs = null;
+
+  /**
+   * "Fuzz" test for the edit log.
+   *
+   * This tests that we can read random garbage from the edit log without
+   * crashing the JVM or throwing an unchecked exception.
+   */
+  @Test
+  public void testFuzzSequences() throws IOException {
+    final int MAX_GARBAGE_LENGTH = 512;
+    final int MAX_INVALID_SEQ = 5000;
+    // The seed to use for our random number generator.  When given the same
+    // seed, Java.util.Random will always produce the same sequence of values.
+    // This is important because it means that the test is deterministic and
+    // repeatable on any machine.
+    final int RANDOM_SEED = 123;
+
+    Random r = new Random(RANDOM_SEED);
+    for (int i = 0; i < MAX_INVALID_SEQ; i++) {
+      byte[] garbage = new byte[r.nextInt(MAX_GARBAGE_LENGTH)];
+      r.nextBytes(garbage);
+      validateNoCrash(garbage);
+    }
+  }
 }