From 9ae68f467ec168e584821ddc0148d26e82bdd99d Mon Sep 17 00:00:00 2001
From: Jean-Michel Trivi <jmtrivi@google.com>
Date: Fri, 8 Nov 2019 16:45:16 -0800
Subject: [PATCH] FocusRequester: fix NPE

Fix NPE and potential race condition in
FocusRequester.dispatchFocusResultFromExtPolicy where mFocusDispatcher
was checked against null, but the method didn't return in that case.

Bug: 142278598
Test: Android Auto with phone call and custom focus policy
Change-Id: I88447a255132c94f8c2fbf97a1e3ee88f6d2e993
Merged-In: I88447a255132c94f8c2fbf97a1e3ee88f6d2e993
---
 .../java/com/android/server/audio/FocusRequester.java | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/services/core/java/com/android/server/audio/FocusRequester.java b/services/core/java/com/android/server/audio/FocusRequester.java
index db55138e446d9..7578948adb14b 100644
--- a/services/core/java/com/android/server/audio/FocusRequester.java
+++ b/services/core/java/com/android/server/audio/FocusRequester.java
@@ -416,7 +416,8 @@ public class FocusRequester {
     }
 
     int dispatchFocusChange(int focusChange) {
-        if (mFocusDispatcher == null) {
+        final IAudioFocusDispatcher fd = mFocusDispatcher;
+        if (fd == null) {
             if (MediaFocusControl.DEBUG) { Log.e(TAG, "dispatchFocusChange: no focus dispatcher"); }
             return AudioManager.AUDIOFOCUS_REQUEST_FAILED;
         }
@@ -436,7 +437,7 @@ public class FocusRequester {
             mFocusLossReceived = focusChange;
         }
         try {
-            mFocusDispatcher.dispatchAudioFocusChange(focusChange, mClientId);
+            fd.dispatchAudioFocusChange(focusChange, mClientId);
         } catch (android.os.RemoteException e) {
             Log.e(TAG, "dispatchFocusChange: error talking to focus listener " + mClientId, e);
             return AudioManager.AUDIOFOCUS_REQUEST_FAILED;
@@ -445,16 +446,18 @@ public class FocusRequester {
     }
 
     void dispatchFocusResultFromExtPolicy(int requestResult) {
-        if (mFocusDispatcher == null) {
+        final IAudioFocusDispatcher fd = mFocusDispatcher;
+        if (fd == null) {
             if (MediaFocusControl.DEBUG) {
                 Log.e(TAG, "dispatchFocusResultFromExtPolicy: no focus dispatcher");
             }
+            return;
         }
         if (DEBUG) {
             Log.v(TAG, "dispatching result" + requestResult + " to " + mClientId);
         }
         try {
-            mFocusDispatcher.dispatchFocusResultFromExtPolicy(requestResult, mClientId);
+            fd.dispatchFocusResultFromExtPolicy(requestResult, mClientId);
         } catch (android.os.RemoteException e) {
             Log.e(TAG, "dispatchFocusResultFromExtPolicy: error talking to focus listener"
                     + mClientId, e);