Index: libpurple/internal.h
===================================================================
--- libpurple/internal.h	(revision 13143)
+++ libpurple/internal.h	(working copy)
@@ -140,6 +140,14 @@
 #	define G_MAXUINT32 ((guint32) 0xffffffff)
 #endif
 
+#ifndef G_MAXSIZE
+#	if GLIB_SIZEOF_LONG == 8
+#		define G_MAXSIZE ((gsize) 0xffffffffffffffff)
+#	else
+#		define G_MAXSIZE ((gsize) 0xffffffff)
+#	endif
+#endif
+
 #if GLIB_CHECK_VERSION(2,6,0)
 #	include <glib/gstdio.h>
 #endif
--- libpurple/protocols/msn/slplink.c.cve-2008-2927	2007-09-29 12:39:09.000000000 -0400
+++ libpurple/protocols/msn/slplink.c	2008-07-10 12:13:12.000000000 -0400
@@ -595,7 +595,7 @@ msn_slplink_process_msg(MsnSlpLink *slpl
 	}
 	else if (slpmsg->size)
 	{
-		if ((offset + len) > slpmsg->size)
+		if (G_MAXSIZE - len < offset || (offset + len) > slpmsg->size)
 		{
 			purple_debug_error("msn", "Oversized slpmsg\n");
 			g_return_if_reached();