From baf2d6448e1558f7c453497c85e5845b46f9cbec Mon Sep 17 00:00:00 2001
From: Jing Ji <jji@google.com>
Date: Wed, 4 Mar 2020 10:31:53 -0800
Subject: [PATCH] Check the isInUse with the lock held in MessageQueue

Fix a potential race condtion when the same message object
is being enqueued by two threads.

Bug: 150263007
Bug: 154867444
Test: atest android.os.cts.MessageQueueTest
Change-Id: Id79448ba8719479cbdb054f2cdd172fdcbe86d47
(cherry picked from commit 96a6fec4d651607f0f0b659dd2e8dccaa9b1ed43)
---
 core/java/android/os/MessageQueue.java | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/core/java/android/os/MessageQueue.java b/core/java/android/os/MessageQueue.java
index dfa5b26142f8c..1a3cf2d2c6345 100644
--- a/core/java/android/os/MessageQueue.java
+++ b/core/java/android/os/MessageQueue.java
@@ -550,11 +550,12 @@ public final class MessageQueue {
         if (msg.target == null) {
             throw new IllegalArgumentException("Message must have a target.");
         }
-        if (msg.isInUse()) {
-            throw new IllegalStateException(msg + " This message is already in use.");
-        }
 
         synchronized (this) {
+            if (msg.isInUse()) {
+                throw new IllegalStateException(msg + " This message is already in use.");
+            }
+
             if (mQuitting) {
                 IllegalStateException e = new IllegalStateException(
                         msg.target + " sending message to a Handler on a dead thread");