better handling of invalid strings in IntSafeCopyUnicodeString()

reactos/subsys/win32k/ntuser

diff -u -r1.60 -r1.61
--- misc.c	14 Apr 2004 23:17:56 -0000	1.60
+++ misc.c	14 Apr 2004 23:40:43 -0000	1.61
@@ -1,4 +1,4 @@

-/* $Id: misc.c,v 1.60 2004/04/14 23:17:56 weiden Exp $

+/* $Id: misc.c,v 1.61 2004/04/14 23:40:43 weiden Exp $

  *
  * COPYRIGHT:        See COPYING in the top level directory
  * PROJECT:          ReactOS kernel

@@ -931,10 +931,16 @@

     return Status;
   }
   

-  if(Dest->Length > 0)

+  if(Dest->Length > 0x4000)
+  {
+    return STATUS_UNSUCCESSFUL;
+  }
+  
+  Src = Dest->Buffer;
+  Dest->Buffer = NULL;
+  
+  if(Dest->Length > 0 && Src)

   {

-    Src = Dest->Buffer;
-    

     Dest->Buffer = ExAllocatePoolWithTag(NonPagedPool, Dest->Length, TAG_STRING);
     if(!Dest->Buffer)
     {