Add pointer check for NULL before dereference it.

Signed-off-by: sfu5
Reviewed-by: xdu2
Reviewed-by: ydong10


git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12514 6f19259b-4bc3-4df7-8a09-765794883524

ShellPkg/Library/UefiShellLib/UefiShellLib.c

@@ -1933,6 +1933,9 @@ InternalCommandLineParse (
   // initialize the linked list
   //
   *CheckPackage = (LIST_ENTRY*)AllocateZeroPool(sizeof(LIST_ENTRY));
+  if (*CheckPackage == NULL) {
+    return EFI_OUT_OF_RESOURCES;
+  }
   InitializeListHead(*CheckPackage);
 
   //