From 4221d79ab269939f7ccdaad321e45ba2f2d347d5 Mon Sep 17 00:00:00 2001
From: Louis Chang <louischang@google.com>
Date: Wed, 17 Apr 2019 17:15:01 +0800
Subject: [PATCH] Fix NPE when scheduling transaction for null client

Application process was crash and the application thread was set
to null when obtaining the client transaction object. NPE was
thrown by using it to schedule transaction.

Bug: 130006936
Test: WindowProcessControllerTests
Test: ActivityStartControllerTests
Test: RootActivityContainerTests

Change-Id: I65ecb124e014e5d80ebc283884475619f95239fa
---
 .../com/android/server/wm/WindowProcessController.java     | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/services/core/java/com/android/server/wm/WindowProcessController.java b/services/core/java/com/android/server/wm/WindowProcessController.java
index eb919eb00f0c4..8e01f0f8ef61a 100644
--- a/services/core/java/com/android/server/wm/WindowProcessController.java
+++ b/services/core/java/com/android/server/wm/WindowProcessController.java
@@ -98,7 +98,7 @@ public class WindowProcessController extends ConfigurationContainer<Configuratio
     private final ActivityTaskManagerService mAtm;
     // The actual proc...  may be null only if 'persistent' is true (in which case we are in the
     // process of launching the app)
-    private volatile IApplicationThread mThread;
+    private IApplicationThread mThread;
     // Currently desired scheduling class
     private volatile int mCurSchedGroup;
     // Currently computed process state
@@ -192,8 +192,11 @@ public class WindowProcessController extends ConfigurationContainer<Configuratio
         return mPid;
     }
 
+    @HotPath(caller = HotPath.PROCESS_CHANGE)
     public void setThread(IApplicationThread thread) {
-        mThread = thread;
+        synchronized (mAtm.mGlobalLockWithoutBoost) {
+            mThread = thread;
+        }
     }
 
     IApplicationThread getThread() {