$NetBSD: patch-ad,v 1.1 2005/05/28 14:15:23 adrianp Exp $

--- print-isoclns.c.orig	2005-05-06 09:11:15.000000000 +0100
+++ print-isoclns.c
@@ -1506,6 +1506,9 @@ static int isis_print (const u_int8_t *p
                tlv_type,
                tlv_len);
 
+	if (tlv_len == 0) /* something is malformed */
+		break;
+
         /* now check if we have a decoder otherwise do a hexdump at the end*/
 	switch (tlv_type) {
 	case TLV_AREA_ADDR:
@@ -1536,7 +1539,7 @@ static int isis_print (const u_int8_t *p
 	    break;
 
         case TLV_ISNEIGH_VARLEN:
-            if (!TTEST2(*tptr, 1))
+            if (!TTEST2(*tptr, 1) || tmp < 3) /* min. TLV length */
 		goto trunctlv;
 	    lan_alen = *tptr++; /* LAN adress length */
             tmp --;