Merge "Guard against overflow errors for transparent regions"
diff --git a/services/surfaceflinger/CompositionEngine/src/Output.cpp b/services/surfaceflinger/CompositionEngine/src/Output.cpp
index 509312f..aea6798 100644
--- a/services/surfaceflinger/CompositionEngine/src/Output.cpp
+++ b/services/surfaceflinger/CompositionEngine/src/Output.cpp
@@ -586,8 +586,29 @@
     // Remove the transparent area from the visible region
     if (!layerFEState->isOpaque) {
         if (tr.preserveRects()) {
-            // transform the transparent region
-            transparentRegion = tr.transform(layerFEState->transparentRegionHint);
+            // Clip the transparent region to geomLayerBounds first
+            // The transparent region may be influenced by applications, for
+            // instance, by overriding ViewGroup#gatherTransparentRegion with a
+            // custom view. Once the layer stack -> display mapping is known, we
+            // must guard against very wrong inputs to prevent underflow or
+            // overflow errors. We do this here by constraining the transparent
+            // region to be within the pre-transform layer bounds, since the
+            // layer bounds are expected to play nicely with the full
+            // transform.
+            const Region clippedTransparentRegionHint =
+                    layerFEState->transparentRegionHint.intersect(
+                            Rect(layerFEState->geomLayerBounds));
+
+            if (clippedTransparentRegionHint.isEmpty()) {
+                if (!layerFEState->transparentRegionHint.isEmpty()) {
+                    ALOGD("Layer: %s had an out of bounds transparent region",
+                          layerFE->getDebugName());
+                    layerFEState->transparentRegionHint.dump("transparentRegionHint");
+                }
+                transparentRegion.clear();
+            } else {
+                transparentRegion = tr.transform(clippedTransparentRegionHint);
+            }
         } else {
             // transformation too complex, can't do the
             // transparent region optimization.
diff --git a/services/surfaceflinger/CompositionEngine/tests/OutputTest.cpp b/services/surfaceflinger/CompositionEngine/tests/OutputTest.cpp
index 505f94e..cf12890 100644
--- a/services/surfaceflinger/CompositionEngine/tests/OutputTest.cpp
+++ b/services/surfaceflinger/CompositionEngine/tests/OutputTest.cpp
@@ -1505,6 +1505,8 @@
     static const Region kTransparentRegionHint;
     static const Region kTransparentRegionHintTwo;
     static const Region kTransparentRegionHintTwo90Rotation;
+    static const Region kTransparentRegionHintNegative;
+    static const Region kTransparentRegionHintNegativeIntersectsBounds;
 
     StrictMock<OutputPartialMock> mOutput;
     LayerFESet mGeomSnapshots;
@@ -1528,6 +1530,10 @@
         Region(Rect(25, 20, 50, 75));
 const Region OutputEnsureOutputLayerIfVisibleTest::kTransparentRegionHintTwo90Rotation =
         Region(Rect(125, 25, 180, 50));
+const Region OutputEnsureOutputLayerIfVisibleTest::kTransparentRegionHintNegative =
+        Region(Rect(INT32_MIN, INT32_MIN, INT32_MIN + 100, INT32_MIN + 200));
+const Region OutputEnsureOutputLayerIfVisibleTest::kTransparentRegionHintNegativeIntersectsBounds =
+        Region(Rect(INT32_MIN, INT32_MIN, 100, 100));
 
 TEST_F(OutputEnsureOutputLayerIfVisibleTest, performsGeomLatchBeforeCheckingIfLayerIncluded) {
     EXPECT_CALL(mOutput, includesLayer(sp<LayerFE>(mLayer.layerFE))).WillOnce(Return(false));
@@ -1997,6 +2003,41 @@
                 RegionEq(kTransparentRegionHintTwo90Rotation));
 }
 
+TEST_F(OutputEnsureOutputLayerIfVisibleTest, transparentRegionExcludesOutputLayer) {
+    mLayer.layerFEState.isOpaque = false;
+    mLayer.layerFEState.contentDirty = true;
+    mLayer.layerFEState.geomLayerBounds = kFullBoundsNoRotation.bounds().toFloatRect();
+    mLayer.layerFEState.transparentRegionHint = kFullBoundsNoRotation;
+
+    EXPECT_CALL(mOutput, ensureOutputLayer(_, _)).Times(0);
+}
+
+TEST_F(OutputEnsureOutputLayerIfVisibleTest, transparentRegionIgnoredWhenOutsideBounds) {
+    mLayer.layerFEState.isOpaque = false;
+    mLayer.layerFEState.contentDirty = true;
+    mLayer.layerFEState.geomLayerBounds = kFullBoundsNoRotation.bounds().toFloatRect();
+    mLayer.layerFEState.transparentRegionHint = kTransparentRegionHintNegative;
+
+    EXPECT_CALL(mOutput, ensureOutputLayer(_, _)).Times(0);
+}
+
+TEST_F(OutputEnsureOutputLayerIfVisibleTest, transparentRegionClipsWhenOutsideBounds) {
+    mLayer.layerFEState.isOpaque = false;
+    mLayer.layerFEState.contentDirty = true;
+    mLayer.layerFEState.compositionType =
+            aidl::android::hardware::graphics::composer3::Composition::DISPLAY_DECORATION;
+    mLayer.layerFEState.transparentRegionHint = kTransparentRegionHintNegativeIntersectsBounds;
+
+    EXPECT_CALL(mOutput, getOutputLayerCount()).WillOnce(Return(0u));
+    EXPECT_CALL(mOutput, ensureOutputLayer(Eq(std::nullopt), Eq(mLayer.layerFE)))
+            .WillOnce(Return(&mLayer.outputLayer));
+    ensureOutputLayerIfVisible();
+
+    // Check that the blocking region clips an out-of-bounds transparent region.
+    EXPECT_THAT(mLayer.outputLayerState.outputSpaceBlockingRegionHint,
+                RegionEq(kTransparentRegionHint));
+}
+
 /*
  * Output::present()
  */