[PATCH] SourceLevelDebugPkg DebugCommLibUsb3: Address NULL ptr dereference case

["Zeng, Star" <star.zeng@intel.com>]

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2051

Original code GetConfigTable for AddrPtr first, if failed,
InstalConfigTable with allocated AddrPtr. So the AddrPtr
should not be NULL and the NULL pointer dereference case
should be false positive. This patch is just to address
the case raised from static analysis.

Cc: Hao A Wu <hao.a.wu@intel.com>
Signed-off-by: Star Zeng <star.zeng@intel.com>
---
 .../DebugCommunicationLibUsb3/DebugCommunicationLibUsb3Dxe.c    | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/SourceLevelDebugPkg/Library/DebugCommunicationLibUsb3/DebugCommunicationLibUsb3Dxe.c b/SourceLevelDebugPkg/Library/DebugCommunicationLibUsb3/DebugCommunicationLibUsb3Dxe.c
index eee30c852ffd..d4245465ce74 100644
--- a/SourceLevelDebugPkg/Library/DebugCommunicationLibUsb3/DebugCommunicationLibUsb3Dxe.c
+++ b/SourceLevelDebugPkg/Library/DebugCommunicationLibUsb3/DebugCommunicationLibUsb3Dxe.c
@@ -447,7 +447,7 @@ DebugCommunicationUsb3DxeConstructor (
   EFI_EVENT                     Event;
 
   Status = EfiGetSystemConfigurationTable (&gUsb3DbgGuid, (VOID **) &AddrPtr);
-  if (EFI_ERROR (Status)) {
+  if (EFI_ERROR (Status) || (AddrPtr == NULL)) {
     //
     // Instead of using local variables, install system configuration table for
     // the local instance and the buffer to save instance address pointer.
-- 
2.21.0.windows.1