[PATCH] EmbeddedPkg/GdbStub: Check DebugImageInfoTable type safely

["Marvin Häuser" <mhaeuser@posteo.de>]

C does not allow casting to or dereferencing incompatible pointer
types. Use the ImageInfoType member of the union first to determine
the data type before dereferencing NormalImage.

Cc: Leif Lindholm <leif@nuviainc.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Abner Chang <abner.chang@hpe.com>
Cc: Daniel Schaefer <daniel.schaefer@hpe.com>
Cc: Vitaly Cheptsov <vit9696@protonmail.com>
Signed-off-by: Marvin Häuser <mhaeuser@posteo.de>
---
 EmbeddedPkg/GdbStub/GdbStub.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/EmbeddedPkg/GdbStub/GdbStub.c b/EmbeddedPkg/GdbStub/GdbStub.c
index 7f2a5ed20011..09167fdafb4d 100644
--- a/EmbeddedPkg/GdbStub/GdbStub.c
+++ b/EmbeddedPkg/GdbStub/GdbStub.c
@@ -1043,8 +1043,8 @@ QxferLibrary (
 
   if (gDebugTable != NULL) {
     for (; gEfiDebugImageTableEntry < gDebugImageTableHeader->TableSize; gEfiDebugImageTableEntry++, gDebugTable++) {
-      if (gDebugTable->NormalImage != NULL) {
-        if ((gDebugTable->NormalImage->ImageInfoType == EFI_DEBUG_IMAGE_INFO_TYPE_NORMAL) &&
+      if (gDebugTable->ImageInfoType != NULL) {
+        if ((*gDebugTable->ImageInfoType == EFI_DEBUG_IMAGE_INFO_TYPE_NORMAL) &&
             (gDebugTable->NormalImage->LoadedImageProtocolInstance != NULL)) {
           Pdb = PeCoffLoaderGetDebuggerInfo (
                  gDebugTable->NormalImage->LoadedImageProtocolInstance->ImageBase,
-- 
2.31.1