SecurityPkg/VariableAuthenticated: Check if there is a NV Variable Storage header prior to use its attributes

The Variable PEI and RuntimeDxe drivers were using the attribute 'HeaderLength' of
EFI_FIRMWARE_VOLUME_HEADER without checking if a Firmware Volume Header was existing at
the base address.
In case the Firmware Volume Header does not exist or is corrupted, the attribute 'HeaderLength'
is a non valid value that can lead to a non valid physical address when accessing produces an
access error.

Signed-off-by: oliviermartin
Reviewed-by: rsun3
Reviewed-by: niruiyu



git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12845 6f19259b-4bc3-4df7-8a09-765794883524

SecurityPkg/VariableAuthenticated/Pei/Variable.h

@@ -29,6 +29,7 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 
 #include <Guid/AuthenticatedVariableFormat.h>
 #include <Guid/VariableIndexTable.h>
+#include <Guid/SystemNvDataGuid.h>
 
 typedef enum {
   VariableStoreTypeHob,