Clear reply before writing exception.

Changes Binder.execTransact() to clear any partial reply before
writing the exception.  Specifically, this fixes case where an
onTransact() could leave a writeNoException() floating in the reply.

Bug: 5686023
Change-Id: Ibc944464a010f5ec2fd8ef3cc84ac23d8260a491

1 files changed, 3 insertions, 0 deletions

diff --git a/core/java/android/os/Binder.java b/core/java/android/os/Binder.java
index c25ebb7..24569fa 100644
--- a/core/java/android/os/Binder.java
+++ b/core/java/android/os/Binder.java
@@ -337,13 +337,16 @@ public class Binder implements IBinder {
         try {
             res = onTransact(code, data, reply, flags);
         } catch (RemoteException e) {
+            reply.setDataPosition(0);
             reply.writeException(e);
             res = true;
         } catch (RuntimeException e) {
+            reply.setDataPosition(0);
             reply.writeException(e);
             res = true;
         } catch (OutOfMemoryError e) {
             RuntimeException re = new RuntimeException("Out of memory", e);
+            reply.setDataPosition(0);
             reply.writeException(re);
             res = true;
         }