Remove the KMS client cache

Author: Bryan Donlan

CHANGELOG.md

@@ -1,5 +1,13 @@
 # Changelog
 
+## 1.3.4
+
+### Minor Changes
+
+* Removed the KMS client cache, which could result in a memory leak when
+decrypting certain malformed ciphertexts. This may reduce performance slightly
+in some scenarios.
+
 ## 1.3.3
 
 ### Minor Changes

src/main/java/com/amazonaws/encryptionsdk/kms/KmsMasterKeyProvider.java

@@ -259,12 +259,10 @@ private RegionalClientSupplier clientFactory() {
             AWSKMSClientBuilder builder = templateBuilder_ != null ? cloneClientBuilder(templateBuilder_)
                                                                    : AWSKMSClientBuilder.standard();
 
-            ConcurrentHashMap<String, AWSKMS> clientCache = new ConcurrentHashMap<>();
-
-            return region -> clientCache.computeIfAbsent(region, region2 -> {
+            return region -> {
                 // Clone yet again as we're going to change the region field.
-                return cloneClientBuilder(builder).withRegion(region2).build();
-            });
+                return cloneClientBuilder(builder).withRegion(region).build();
+            };
         }
     }