diff --git a/opengl/libs/EGL/egl_display.cpp b/opengl/libs/EGL/egl_display.cpp
index 4e5833a..3c1edd1 100644
--- a/opengl/libs/EGL/egl_display.cpp
+++ b/opengl/libs/EGL/egl_display.cpp
@@ -79,6 +79,10 @@
 }
 
 egl_display_t* egl_display_t::get(EGLDisplay dpy) {
+    if (uintptr_t(dpy) == 0) {
+        return nullptr;
+    }
+
     uintptr_t index = uintptr_t(dpy)-1U;
     if (index >= NUM_DISPLAYS || !sDisplay[index].isValid()) {
         return nullptr;
diff --git a/services/surfaceflinger/RenderEngine/GLES20RenderEngine.cpp b/services/surfaceflinger/RenderEngine/GLES20RenderEngine.cpp
index 37a530b..9c0af8b 100644
--- a/services/surfaceflinger/RenderEngine/GLES20RenderEngine.cpp
+++ b/services/surfaceflinger/RenderEngine/GLES20RenderEngine.cpp
@@ -166,12 +166,12 @@
         size_t vpw, size_t vph, Rect sourceCrop, size_t hwh, bool yswap,
         Transform::orientation_flags rotation) {
 
-    size_t l = sourceCrop.left;
-    size_t r = sourceCrop.right;
+    int32_t l = sourceCrop.left;
+    int32_t r = sourceCrop.right;
 
     // In GL, (0, 0) is the bottom-left corner, so flip y coordinates
-    size_t t = hwh - sourceCrop.top;
-    size_t b = hwh - sourceCrop.bottom;
+    int32_t t = hwh - sourceCrop.top;
+    int32_t b = hwh - sourceCrop.bottom;
 
     mat4 m;
     if (yswap) {
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 0b5262d..624fda2 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -2131,7 +2131,7 @@
             // (ie: in drawing state but not in current state)
             // also handle displays that changed
             // (ie: displays that are in both lists)
-            for (size_t i=0 ; i<dc ; i++) {
+            for (size_t i=0 ; i<dc ;) {
                 const ssize_t j = curr.indexOfKey(draw.keyAt(i));
                 if (j < 0) {
                     // in drawing state but not in current state
@@ -2166,7 +2166,7 @@
                             hw->disconnect(getHwComposer());
                         mDisplays.removeItem(display);
                         mDrawingState.displays.removeItemsAt(i);
-                        dc--; i--;
+                        dc--;
                         // at this point we must loop to the next item
                         continue;
                     }
@@ -2188,6 +2188,7 @@
                         }
                     }
                 }
+                ++i;
             }
 
             // find displays that were added