From 1ec53ec50776cd1c6539bd5e339a951b990a1c76 Mon Sep 17 00:00:00 2001
From: Andrei Onea <andreionea@google.com>
Date: Wed, 24 Feb 2021 15:24:39 +0000
Subject: Fix deadlock on CompatConfig.mChanges

Only lock mChanges long enough to get a local copy of the list of
changes.

Bug: 181021273

Change-Id: I22e97e58b4fe9dbc70d11660f93c4afb5d514d24
---
 .../com/android/server/compat/CompatConfig.java    | 23 ++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/services/core/java/com/android/server/compat/CompatConfig.java b/services/core/java/com/android/server/compat/CompatConfig.java
index 422991e082a9..66a652053857 100644
--- a/services/core/java/com/android/server/compat/CompatConfig.java
+++ b/services/core/java/com/android/server/compat/CompatConfig.java
@@ -50,6 +50,7 @@ import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.PrintWriter;
+import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
@@ -595,18 +596,24 @@ final class CompatConfig {
      * Rechecks all the existing overrides for a package.
      */
     void recheckOverrides(String packageName) {
+        // Local cache of compat changes. Holding a lock on mChanges for the whole duration of the
+        // method will cause a deadlock.
+        List<CompatChange> changes;
         synchronized (mChanges) {
-            boolean shouldInvalidateCache = false;
+            changes = new ArrayList<>(mChanges.size());
             for (int idx = 0; idx < mChanges.size(); ++idx) {
-                CompatChange c = mChanges.valueAt(idx);
-                OverrideAllowedState allowedState =
-                        mOverrideValidator.getOverrideAllowedState(c.getId(), packageName);
-                shouldInvalidateCache |= c.recheckOverride(packageName, allowedState, mContext);
-            }
-            if (shouldInvalidateCache) {
-                invalidateCache();
+                changes.add(mChanges.valueAt(idx));
             }
         }
+        boolean shouldInvalidateCache = false;
+        for (CompatChange c: changes) {
+            OverrideAllowedState allowedState =
+                    mOverrideValidator.getOverrideAllowedState(c.getId(), packageName);
+            shouldInvalidateCache |= c.recheckOverride(packageName, allowedState, mContext);
+        }
+        if (shouldInvalidateCache) {
+            invalidateCache();
+        }
     }
 
     void registerContentObserver() {
-- 
cgit v1.2.3-59-g8ed1b