$NetBSD: patch-ag,v 1.1 2008/04/01 15:51:25 tonnerre Exp $

Fix buffer overflow vulnerability derived from old code (CVE-2006-4484).

--- pTk/mTk/generic/tkImgGIF.c.orig	2004-02-29 11:20:28.000000000 +0100
+++ pTk/mTk/generic/tkImgGIF.c
@@ -826,7 +826,7 @@ ReadImage(interp, imagePtr, chan, len, r
     /*
      *  Initialize the decoder
      */
-    if (! ReadOK(chan, &initialCodeSize, 1))  {
+    if (! ReadOK(chan, &initialCodeSize, 1) || initialCodeSize > MAX_LWZ_BITS)  {
 	Tcl_AppendResult(interp, "error reading GIF image: ",
 		Tcl_PosixError(interp), (char *) NULL);
 	return TCL_ERROR;