Use serial executor for permission operations.

If the methods are called concurrently and we are calling
AppPermissions.persistChanges(), we might be overwriting the state
that have been changed by another thread but not reflected in our
state obtained earlier.

Fixes: 133398449
Test: presubmit
Change-Id: I63f715bafbf0ce24e75246930c7b271ee64b2e1b

1 files changed, 8 insertions, 10 deletions

diff --git a/src/com/android/packageinstaller/permission/service/PermissionControllerServiceImpl.java b/src/com/android/packageinstaller/permission/service/PermissionControllerServiceImpl.java
index 6427ba36..d846ce09 100644
--- a/src/com/android/packageinstaller/permission/service/PermissionControllerServiceImpl.java
+++ b/src/com/android/packageinstaller/permission/service/PermissionControllerServiceImpl.java
@@ -67,9 +67,8 @@ import java.util.function.IntConsumer;
 /**
  * Calls from the system into the permission controller.
  *
- * All methods are called async beside the backup related method. For these we force to use the
- * async-task single thread executor so that multiple parallel backups don't override the delayed
- * the backup state racily.
+ * All reading methods are called async, and all writing method are called on the AsyncTask single
+ * thread executor so that multiple writes won't override each other concurrently.
  */
 public final class PermissionControllerServiceImpl extends PermissionControllerService {
     private static final String LOG_TAG = PermissionControllerServiceImpl.class.getSimpleName();
@@ -210,8 +209,8 @@ public final class PermissionControllerServiceImpl extends PermissionControllerS
     public void onRevokeRuntimePermissions(@NonNull Map<String, List<String>> request,
             boolean doDryRun, int reason, @NonNull String callerPackageName,
             @NonNull Consumer<Map<String, List<String>>> callback) {
-        AsyncTask.THREAD_POOL_EXECUTOR.execute(() -> callback.accept(
-                onRevokeRuntimePermissions(request, doDryRun, reason, callerPackageName)));
+        AsyncTask.execute(() -> callback.accept(onRevokeRuntimePermissions(request, doDryRun,
+                reason, callerPackageName)));
     }
 
     private @NonNull Map<String, List<String>> onRevokeRuntimePermissions(
@@ -403,7 +402,7 @@ public final class PermissionControllerServiceImpl extends PermissionControllerS
     @Override
     public void onRevokeRuntimePermission(@NonNull String packageName,
             @NonNull String permissionName, @NonNull Runnable callback) {
-        AsyncTask.THREAD_POOL_EXECUTOR.execute(() -> {
+        AsyncTask.execute(() -> {
             onRevokeRuntimePermission(packageName, permissionName);
             callback.run();
         });
@@ -503,9 +502,8 @@ public final class PermissionControllerServiceImpl extends PermissionControllerS
     public void onSetRuntimePermissionGrantStateByDeviceAdmin(@NonNull String callerPackageName,
             @NonNull String packageName, @NonNull String unexpandedPermission, int grantState,
             @NonNull Consumer<Boolean> callback) {
-        AsyncTask.THREAD_POOL_EXECUTOR.execute(() -> callback.accept(
-                onSetRuntimePermissionGrantStateByDeviceAdmin(callerPackageName, packageName,
-                        unexpandedPermission, grantState)));
+        AsyncTask.execute(() -> callback.accept(onSetRuntimePermissionGrantStateByDeviceAdmin(
+                callerPackageName, packageName, unexpandedPermission, grantState)));
     }
 
     private boolean onSetRuntimePermissionGrantStateByDeviceAdmin(@NonNull String callerPackageName,
@@ -568,7 +566,7 @@ public final class PermissionControllerServiceImpl extends PermissionControllerS
 
     @Override
     public void onGrantOrUpgradeDefaultRuntimePermissions(@NonNull Runnable callback) {
-        AsyncTask.THREAD_POOL_EXECUTOR.execute(() -> {
+        AsyncTask.execute(() -> {
             onGrantOrUpgradeDefaultRuntimePermissions();
             callback.run();
         });