[PATCH 1/1] MdePkg/Base.h: Implement BASE_CR() via OFFSET_OF().

["Marvin Häuser" <Marvin.Haeuser@outlook.com>]

Replace the current NULL pointer dereference to retrieve Field's
offset with a call to OFFSET_OF().  This is implemented via
__builtin_offsetof for GCC and Clang, which eliminates UB caught by
Clang UndefinedBehaviorSanitizer.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Marvin Haeuser <Marvin.Haeuser@outlook.com>
---
 MdePkg/Include/Base.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/MdePkg/Include/Base.h b/MdePkg/Include/Base.h
index 523192fd79fc..bc877d8125a5 100644
--- a/MdePkg/Include/Base.h
+++ b/MdePkg/Include/Base.h
@@ -869,7 +869,7 @@ typedef UINTN  *BASE_LIST;
   @return  A pointer to the structure from one of it's elements.
 
 **/
-#define BASE_CR(Record, TYPE, Field)  ((TYPE *) ((CHAR8 *) (Record) - (CHAR8 *) &(((TYPE *) 0)->Field)))
+#define BASE_CR(Record, TYPE, Field)  ((TYPE *) ((CHAR8 *) (Record) - OFFSET_OF (TYPE, Field)))
 
 /**
   Rounds a value up to the next boundary using a specified alignment.
-- 
2.19.1.windows.1