MdePkg/PiFirmwareFile: fix undefined behavior in FFS_FILE_SIZE

Accessing "EFI_FFS_FILE_HEADER.Size", which is of type UINT8[3], through a
(UINT32*), is undefined behavior. Fix it by accessing the array elements
individually.

Cc: Liming Gao <liming.gao@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Bugzilla: https://bugzilla.tianocore.org/show_bug.cgi?id=1710
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Philippe Mathieu-Daude <philmd@redhat.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

diff --git a/MdePkg/Include/Pi/PiFirmwareFile.h b/MdePkg/Include/Pi/PiFirmwareFile.h
index 05470538de4205a709b8959175adfc2d29a3765b..ec7729e9c36e5b2910d07e32999a284095cde394 100644 (file)
--- a/MdePkg/Include/Pi/PiFirmwareFile.h
+++ b/MdePkg/Include/Pi/PiFirmwareFile.h
@@ -179,8 +179,15 @@ typedef struct {
 #define IS_FFS_FILE2(FfsFileHeaderPtr) \\r
     (((((EFI_FFS_FILE_HEADER *) (UINTN) FfsFileHeaderPtr)->Attributes) & FFS_ATTRIB_LARGE_FILE) == FFS_ATTRIB_LARGE_FILE)\r
 \r
-#define FFS_FILE_SIZE(FfsFileHeaderPtr) \\r
-    ((UINT32) (*((UINT32 *) ((EFI_FFS_FILE_HEADER *) (UINTN) FfsFileHeaderPtr)->Size) & 0x00ffffff))\r
+///\r
+/// The argument passed as the FfsFileHeaderPtr parameter to the\r
+/// FFS_FILE_SIZE() function-like macro below must not have side effects:\r
+/// FfsFileHeaderPtr is evaluated multiple times.\r
+///\r
+#define FFS_FILE_SIZE(FfsFileHeaderPtr) ((UINT32) ( \\r
+    (((EFI_FFS_FILE_HEADER *) (UINTN) (FfsFileHeaderPtr))->Size[0]      ) | \\r
+    (((EFI_FFS_FILE_HEADER *) (UINTN) (FfsFileHeaderPtr))->Size[1] <<  8) | \\r
+    (((EFI_FFS_FILE_HEADER *) (UINTN) (FfsFileHeaderPtr))->Size[2] << 16)))\r
 \r
 #define FFS_FILE2_SIZE(FfsFileHeaderPtr) \\r
     ((UINT32) (((EFI_FFS_FILE_HEADER2 *) (UINTN) FfsFileHeaderPtr)->ExtendedSize))\r