Add more check to avoid access violation.

Signed-off-by: ydong10
Reviewed-by: lgao4

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12470 6f19259b-4bc3-4df7-8a09-765794883524

EdkCompatibilityPkg/Foundation/Library/Dxe/EfiIfrSupportLib/IfrCommon.c

@@ -582,7 +582,7 @@ Returns:
   //
   // Return an error if buffer is too small
   //
-  if (SizeOfNvStore > *ImageLength) {
+  if (SizeOfNvStore > *ImageLength || DefaultImage == NULL) {
     gBS->FreePool (OldData);
     *ImageLength = (UINT16) SizeOfNvStore;
     return EFI_BUFFER_TOO_SMALL;