Fix potential heap data leak in mediadrmserver

Change-Id: Ife4cecaeb5e301d702681c6dba9a17357232db40
related-to-bug: 31657897
diff --git a/media/libmedia/ICrypto.cpp b/media/libmedia/ICrypto.cpp
index 495e3f9..302e6ee 100644
--- a/media/libmedia/ICrypto.cpp
+++ b/media/libmedia/ICrypto.cpp
@@ -373,7 +373,7 @@
                     // data back via the shared buffer rather than
                     // copying it separately over binder to avoid
                     // binder's 1MB limit.
-                    memcpy(sharedBuffer->pointer(), dstPtr, totalSize);
+                    memcpy(sharedBuffer->pointer(), dstPtr, result);
                 }
                 free(dstPtr);
                 dstPtr = NULL;