ShellPkg: Add checking for memory allocation and pointer returns from functions.

signed-off-by: jcarsey
reviewed-by: geekboy15a

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12540 6f19259b-4bc3-4df7-8a09-765794883524

ShellPkg/Library/UefiShellDebug1CommandsLib/UefiShellDebug1CommandsLib.c

@@ -303,6 +303,9 @@ ConvertStringToGuid (
   } 
   TempCopy = NULL;
   TempCopy = StrnCatGrow(&TempCopy, NULL, StringGuid, 0);
+  if (TempCopy == NULL) {
+    return (EFI_OUT_OF_RESOURCES);
+  }
   Walker   = TempCopy;
   TempSpot = StrStr(Walker, L"-");
   if (TempSpot != NULL) {