From 3b8e8d76315f6718a982d5e6a019b3aa4f634bcd Mon Sep 17 00:00:00 2001
From: Charles Chen <charlesccchen@google.com>
Date: Wed, 8 Jul 2020 14:09:10 +0800
Subject: [PATCH] Fix NPE when invoking Context#isUiContext

Add null checks in both ContextWrapper and before obtaining
ContextImpl#getOuterContext.

Test: atest ContextTest#testIsUiContext_ContextWrapper
fixes: 160037462
Change-Id: Ic6a71dd9ac4b195d219d6e5431f2f2b199a400fa
---
 core/java/android/app/ContextImpl.java        | 39 +++++++++++--------
 core/java/android/content/ContextWrapper.java |  3 ++
 .../src/android/content/ContextTest.java      | 23 +++++++++++
 3 files changed, 48 insertions(+), 17 deletions(-)

diff --git a/core/java/android/app/ContextImpl.java b/core/java/android/app/ContextImpl.java
index a828aac78dede..505b498e3cf6f 100644
--- a/core/java/android/app/ContextImpl.java
+++ b/core/java/android/app/ContextImpl.java
@@ -1900,26 +1900,31 @@ class ContextImpl extends Context {
 
     @Override
     public Object getSystemService(String name) {
-        // We may override this API from outer context.
-        final boolean isUiContext = isUiContext() || getOuterContext().isUiContext();
-        // Check incorrect Context usage.
-        if (isUiComponent(name) && !isUiContext && vmIncorrectContextUseEnabled()) {
-            final String errorMessage = "Tried to access visual service "
-                    + SystemServiceRegistry.getSystemServiceClassName(name)
-                    + " from a non-visual Context:" + getOuterContext();
-            final String message = "Visual services, such as WindowManager, WallpaperService or "
-                    + "LayoutInflater should be accessed from Activity or other visual Context. "
-                    + "Use an Activity or a Context created with "
-                    + "Context#createWindowContext(int, Bundle), which are adjusted to the "
-                    + "configuration and visual bounds of an area on screen.";
-            final Exception exception = new IllegalAccessException(errorMessage);
-            StrictMode.onIncorrectContextUsed(message, exception);
-            Log.e(TAG, errorMessage + message, exception);
+        if (vmIncorrectContextUseEnabled()) {
+            // We may override this API from outer context.
+            final boolean isUiContext = isUiContext() || isOuterUiContext();
+            // Check incorrect Context usage.
+            if (isUiComponent(name) && !isUiContext) {
+                final String errorMessage = "Tried to access visual service "
+                        + SystemServiceRegistry.getSystemServiceClassName(name)
+                        + " from a non-visual Context:" + getOuterContext();
+                final String message = "Visual services, such as WindowManager, WallpaperService "
+                        + "or LayoutInflater should be accessed from Activity or other visual "
+                        + "Context. Use an Activity or a Context created with "
+                        + "Context#createWindowContext(int, Bundle), which are adjusted to "
+                        + "the configuration and visual bounds of an area on screen.";
+                final Exception exception = new IllegalAccessException(errorMessage);
+                StrictMode.onIncorrectContextUsed(message, exception);
+                Log.e(TAG, errorMessage + " " + message, exception);
+            }
         }
-
         return SystemServiceRegistry.getSystemService(this, name);
     }
 
+    private boolean isOuterUiContext() {
+        return getOuterContext() != null && getOuterContext().isUiContext();
+    }
+
     @Override
     public String getSystemServiceName(Class<?> serviceClass) {
         return SystemServiceRegistry.getSystemServiceName(serviceClass);
@@ -2371,7 +2376,7 @@ class ContextImpl extends Context {
         context.setResources(createResources(mToken, mPackageInfo, mSplitName, displayId,
                 overrideConfiguration, getDisplayAdjustments(displayId).getCompatibilityInfo(),
                 mResources.getLoaders()));
-        context.mIsUiContext = isUiContext() || getOuterContext().isUiContext();
+        context.mIsUiContext = isUiContext() || isOuterUiContext();
         return context;
     }
 
diff --git a/core/java/android/content/ContextWrapper.java b/core/java/android/content/ContextWrapper.java
index 5dc41e483640a..89abfc95d634c 100644
--- a/core/java/android/content/ContextWrapper.java
+++ b/core/java/android/content/ContextWrapper.java
@@ -1151,6 +1151,9 @@ public class ContextWrapper extends Context {
      */
     @Override
     public boolean isUiContext() {
+        if (mBase == null) {
+            return false;
+        }
         return mBase.isUiContext();
     }
 }
diff --git a/core/tests/coretests/src/android/content/ContextTest.java b/core/tests/coretests/src/android/content/ContextTest.java
index 17d1389a66026..777f4a3e03a8b 100644
--- a/core/tests/coretests/src/android/content/ContextTest.java
+++ b/core/tests/coretests/src/android/content/ContextTest.java
@@ -23,6 +23,7 @@ import static android.view.Display.DEFAULT_DISPLAY;
 import static com.google.common.truth.Truth.assertThat;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
 import android.app.ActivityThread;
@@ -180,4 +181,26 @@ public class ContextTest {
                 VIRTUAL_DISPLAY_FLAG_PUBLIC | VIRTUAL_DISPLAY_FLAG_OWN_CONTENT_ONLY);
         return virtualDisplay.getDisplay();
     }
+
+    @Test
+    public void testIsUiContext_ContextWrapper() {
+        ContextWrapper wrapper = new ContextWrapper(null /* base */);
+
+        assertFalse(wrapper.isUiContext());
+
+        wrapper = new ContextWrapper(new TestUiContext());
+
+        assertTrue(wrapper.isUiContext());
+    }
+
+    private static class TestUiContext extends ContextWrapper {
+        TestUiContext() {
+            super(null /* base */);
+        }
+
+        @Override
+        public boolean isUiContext() {
+            return true;
+        }
+    }
 }