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Commit 129aa448 authored by Rhed Jao's avatar Rhed Jao
Browse files

Add a synchronized lock into the SplitDependencyLoaderImpl 

- There's a potential race condition going on when components
  from the isolated split are creating the split class loader.
  Add a synchronized lock for the array of cached class loaders
  and resource paths to prevent the race.

- Remove the synchronized class reference of LoadedApk. Using an
  explicit mLock object to synchronize the
  #createOrUpdateClassLoaderLocked() and cached split class loader
  instead.

Bug: 172602571
Test: atest IsolatedSplitsTests
Test: atest ClassloaderSplitsTest
Test: atest SplitTests
Change-Id: Ifb77d067ddf06b5192d7ce9d4e78958b56faac7c
parent 01f110bf

core/java/android/app/LoadedApk.java

+40 −25
Original line number Diff line number Diff line
@@ -58,6 +58,7 @@ import android.util.Slog; 
import android.util.SparseArray;

import android.view.DisplayAdjustments;



import com.android.internal.annotations.GuardedBy;

import com.android.internal.util.ArrayUtils;



import dalvik.system.BaseDexClassLoader;
@@ -156,6 +157,7 @@ public final class LoadedApk { 
    private final ArrayMap<Context, ArrayMap<ServiceConnection, LoadedApk.ServiceDispatcher>> mUnboundServices

        = new ArrayMap<>();

    private AppComponentFactory mAppComponentFactory;

    private final Object mLock = new Object();



    Application getApplication() {

        return mApplication;
@@ -354,7 +356,7 @@ public final class LoadedApk { 
        } else {

            addedPaths.addAll(newPaths);

        }

        synchronized (this) {

        synchronized (mLock) {

            createOrUpdateClassLoaderLocked(addedPaths);

            if (mResources != null) {

                final String[] splitPaths;
@@ -589,7 +591,9 @@ public final class LoadedApk { 
     * include the base APK in the list of splits.

     */

    private class SplitDependencyLoaderImpl extends SplitDependencyLoader<NameNotFoundException> {

        @GuardedBy("mLock")

        private final String[][] mCachedResourcePaths;

        @GuardedBy("mLock")

        private final ClassLoader[] mCachedClassLoaders;



        SplitDependencyLoaderImpl(@NonNull SparseArray<int[]> dependencies) {
@@ -600,12 +604,15 @@ public final class LoadedApk { 


        @Override

        protected boolean isSplitCached(int splitIdx) {

            synchronized (mLock) {

                return mCachedClassLoaders[splitIdx] != null;

            }

        }



        @Override

        protected void constructSplit(int splitIdx, @NonNull int[] configSplitIndices,

                int parentSplitIdx) throws NameNotFoundException {

            synchronized (mLock) {

                final ArrayList<String> splitPaths = new ArrayList<>();

                if (splitIdx == 0) {

                    createOrUpdateClassLoaderLocked(null);
@@ -622,8 +629,8 @@ public final class LoadedApk { 
                // Since we handled the special base case above, parentSplitIdx is always valid.

                final ClassLoader parent = mCachedClassLoaders[parentSplitIdx];

                mCachedClassLoaders[splitIdx] = ApplicationLoaders.getDefault().getClassLoader(

                    mSplitAppDirs[splitIdx - 1], getTargetSdkVersion(), false, null, null, parent,

                    mSplitClassLoaderNames[splitIdx - 1]);

                        mSplitAppDirs[splitIdx - 1], getTargetSdkVersion(), false, null,

                        null, parent, mSplitClassLoaderNames[splitIdx - 1]);



                Collections.addAll(splitPaths, mCachedResourcePaths[parentSplitIdx]);

                splitPaths.add(mSplitResDirs[splitIdx - 1]);
@@ -632,6 +639,7 @@ public final class LoadedApk { 
                }

                mCachedResourcePaths[splitIdx] = splitPaths.toArray(new String[splitPaths.size()]);

            }

        }



        private int ensureSplitLoaded(String splitName) throws NameNotFoundException {

            int idx = 0;
@@ -648,11 +656,17 @@ public final class LoadedApk { 
        }



        ClassLoader getClassLoaderForSplit(String splitName) throws NameNotFoundException {

            return mCachedClassLoaders[ensureSplitLoaded(splitName)];

            final int idx = ensureSplitLoaded(splitName);

            synchronized (mLock) {

                return mCachedClassLoaders[idx];

            }

        }



        String[] getSplitPathsForSplit(String splitName) throws NameNotFoundException {

            return mCachedResourcePaths[ensureSplitLoaded(splitName)];

            final int idx = ensureSplitLoaded(splitName);

            synchronized (mLock) {

                return mCachedResourcePaths[idx];

            }

        }

    }
@@ -749,6 +763,7 @@ public final class LoadedApk { 
        }

    }



    @GuardedBy("mLock")

    private void createOrUpdateClassLoaderLocked(List<String> addedPaths) {

        if (mPackageName.equals("android")) {

            // Note: This branch is taken for system server and we don't need to setup
@@ -1023,7 +1038,7 @@ public final class LoadedApk { 


    @UnsupportedAppUsage

    public ClassLoader getClassLoader() {

        synchronized (this) {

        synchronized (mLock) {

            if (mClassLoader == null) {

                createOrUpdateClassLoaderLocked(null /*addedPaths*/);

            }