From ba75b774fa45487f820e3a55765ecb9b820d18fc Mon Sep 17 00:00:00 2001
From: Santos Cordon <santoscordon@google.com>
Date: Tue, 15 Mar 2022 10:11:49 +0000
Subject: [PATCH] Add NPE check in ColorFade.

There is a delay between when a display is removed in the
DisplayManager thread and when the ColorFade is dismissed in the
PowerManager thread which can leave ColorFade in a state where its
associated display is no longer available. Check for valid display
similar to how we are doing in other parts of the ColorFade
code.

Bug: 220650894
Test: atest ColorFadeTest
Change-Id: I75528bf4cd398999e012c3c8d8c53b6ac0ce1552
---
 .../com/android/server/display/ColorFade.java |  8 +-
 .../android/server/display/ColorFadeTest.java | 75 +++++++++++++++++++
 2 files changed, 82 insertions(+), 1 deletion(-)
 create mode 100644 services/tests/servicestests/src/com/android/server/display/ColorFadeTest.java

diff --git a/services/core/java/com/android/server/display/ColorFade.java b/services/core/java/com/android/server/display/ColorFade.java
index 7cb29215b5bf..cb04ddfd636d 100644
--- a/services/core/java/com/android/server/display/ColorFade.java
+++ b/services/core/java/com/android/server/display/ColorFade.java
@@ -156,9 +156,15 @@ final class ColorFade {
 
         mMode = mode;
 
+        DisplayInfo displayInfo = mDisplayManagerInternal.getDisplayInfo(mDisplayId);
+        if (displayInfo == null) {
+            // displayInfo can be null if the associated display has been removed. There
+            // is a delay between the display being removed and ColorFade being dismissed.
+            return false;
+        }
+
         // Get the display size and layer stack.
         // This is not expected to change while the color fade surface is showing.
-        DisplayInfo displayInfo = mDisplayManagerInternal.getDisplayInfo(mDisplayId);
         mDisplayLayerStack = displayInfo.layerStack;
         mDisplayWidth = displayInfo.getNaturalWidth();
         mDisplayHeight = displayInfo.getNaturalHeight();
diff --git a/services/tests/servicestests/src/com/android/server/display/ColorFadeTest.java b/services/tests/servicestests/src/com/android/server/display/ColorFadeTest.java
new file mode 100644
index 000000000000..26a83a23de33
--- /dev/null
+++ b/services/tests/servicestests/src/com/android/server/display/ColorFadeTest.java
@@ -0,0 +1,75 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.display;
+
+import static androidx.test.platform.app.InstrumentationRegistry.getInstrumentation;
+
+import static org.junit.Assert.assertFalse;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.when;
+
+import android.content.Context;
+import android.hardware.display.DisplayManagerInternal;
+import android.platform.test.annotations.Presubmit;
+
+import androidx.test.filters.SmallTest;
+import androidx.test.runner.AndroidJUnit4;
+
+import com.android.server.LocalServices;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+
+@SmallTest
+@Presubmit
+@RunWith(AndroidJUnit4.class)
+public class ColorFadeTest {
+    private static final int DISPLAY_ID = 123;
+
+    private Context mContext;
+
+    @Mock private DisplayManagerInternal mDisplayManagerInternalMock;
+
+    @Before
+    public void setUp() {
+        MockitoAnnotations.initMocks(this);
+        addLocalServiceMock(DisplayManagerInternal.class, mDisplayManagerInternalMock);
+        mContext = getInstrumentation().getTargetContext();
+    }
+
+    @After
+    public void tearDown() {
+        LocalServices.removeServiceForTest(DisplayManagerInternal.class);
+    }
+
+    @Test
+    public void testPrepareColorFadeForInvalidDisplay() {
+        when(mDisplayManagerInternalMock.getDisplayInfo(eq(DISPLAY_ID))).thenReturn(null);
+        ColorFade colorFade = new ColorFade(DISPLAY_ID);
+        assertFalse(colorFade.prepare(mContext, ColorFade.MODE_FADE));
+    }
+
+    private static <T> void addLocalServiceMock(Class<T> clazz, T mock) {
+        LocalServices.removeServiceForTest(clazz);
+        LocalServices.addService(clazz, mock);
+    }
+
+}