Brought in change from rev 1.13: check udp length for sanity.

svn path=/stable/2.1/; revision=10105

sys/netinet/udp_usrreq.c

@@ -31,7 +31,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)udp_usrreq.c	8.4 (Berkeley) 1/21/94
- * $Id: udp_usrreq.c,v 1.11 1995/05/09 13:35:48 davidg Exp $
+ * $Id: udp_usrreq.c,v 1.12 1995/05/30 08:10:02 rgrimes Exp $
  */
 
 #include <sys/param.h>
@@ -137,7 +137,7 @@ udp_input(m, iphlen)
 	 */
 	len = ntohs((u_short)uh->uh_ulen);
 	if (ip->ip_len != len) {
-		if (len > ip->ip_len) {
+		if (len > ip->ip_len || len < sizeof(struct udphdr)) {
 			udpstat.udps_badlen++;
 			goto bad;
 		}