Make sure the given display is a valid pointer.

src/libANGLE/Display.cpp

@@ -713,6 +713,20 @@ bool Display::isValidNativeWindow(EGLNativeWindowType window) const
     return mImplementation->isValidNativeWindow(window);
 }
 
+bool Display::isValidDisplay(const egl::Display *display)
+{
+    const DisplayMap *displayMap = GetDisplayMap();
+    for (const auto &displayPair : *displayMap)
+    {
+        if (displayPair.second == display)
+        {
+            return true;
+        }
+    }
+
+    return false;
+}
+
 bool Display::isValidNativeDisplay(EGLNativeDisplayType display)
 {
     // TODO(jmadill): handle this properly

src/libANGLE/Display.h

@@ -81,6 +81,7 @@ class Display final : angle::NonCopyable
     bool isValidSurface(egl::Surface *surface) const;
     bool isValidNativeWindow(EGLNativeWindowType window) const;
 
+    static bool isValidDisplay(const egl::Display *display);
     static bool isValidNativeDisplay(EGLNativeDisplayType display);
     static bool hasExistingWindowSurface(EGLNativeWindowType window);
 

src/libANGLE/validationEGL.cpp

@@ -22,12 +22,17 @@ Error ValidateDisplay(const Display *display)
 {
     if (display == EGL_NO_DISPLAY)
     {
-        return Error(EGL_BAD_DISPLAY);
+        return Error(EGL_BAD_DISPLAY, "display is EGL_NO_DISPLAY.");
+    }
+
+    if (!Display::isValidDisplay(display))
+    {
+        return Error(EGL_BAD_DISPLAY, "display is not a valid display.");
     }
 
     if (!display->isInitialized())
     {
-        return Error(EGL_NOT_INITIALIZED);
+        return Error(EGL_NOT_INITIALIZED, "display is not initialized.");
     }
 
     return Error(EGL_SUCCESS);