Check mDataPos to see if the Parcel needs to grow

Flag: EXEMPT bug fix
Ignore-AOSP-First: security fix
Test: atest binderUnitTest
Bug: 399155883
Change-Id: I38b755ca3381cfca3300292873f763823fbf169b
diff --git a/libs/binder/Parcel.cpp b/libs/binder/Parcel.cpp
index 777c22a..2c37624 100644
--- a/libs/binder/Parcel.cpp
+++ b/libs/binder/Parcel.cpp
@@ -542,7 +542,7 @@
         return BAD_VALUE;
     }
 
-    if ((mDataSize+len) > mDataCapacity) {
+    if ((mDataPos + len) > mDataCapacity) {
         // grow data
         err = growData(len);
         if (err != NO_ERROR) {