From 119329bdfbebf3826859000472afbcdb50ad96d8 Mon Sep 17 00:00:00 2001
From: Michael Wachenschwanz <mwachens@google.com>
Date: Wed, 15 May 2019 22:58:15 -0700
Subject: [PATCH] Clear the Parcel before writing an exception during a
 transaction

This prevents any object data from being accidentally overwritten by the
exception, which could cause unexpected malformed objects to be sent
across the transaction.

Test: atest CtsOsTestCases:ParcelTest#testExceptionOverwritesObject
Fixes: 34175893
Change-Id: Iaf80a0ad711762992b8ae60f76d861c97a403013
---
 core/java/android/os/Binder.java | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/core/java/android/os/Binder.java b/core/java/android/os/Binder.java
index f4a83910e652..cd0e5ea76551 100644
--- a/core/java/android/os/Binder.java
+++ b/core/java/android/os/Binder.java
@@ -413,6 +413,8 @@ private boolean execTransact(int code, int dataObj, int replyObj,
             if ((flags & FLAG_ONEWAY) != 0) {
                 Log.w(TAG, "Caught a RuntimeException from the binder stub implementation.", e);
             }
+            // Clear the parcel before writing the exception
+            reply.setDataSize(0);
             reply.setDataPosition(0);
             reply.writeException(e);
             res = true;
