When an IPv6 packet is received for a raw socket which has the

IPPROTO_IPV6 level socket option IPV6_CHECKSUM enabled and the
checksum check fails, drop the message. Without this fix, an
ICMP6 message was sent indicating a parameter problem.

Thanks to bz@ for suggesting a way to simplify this fix.

Reviewed by:		bz@
MFC after:		1 week
Sponsored by:		Netflix, Inc.
Differential Revision:	https://reviews.freebsd.org/D19969

sys/netinet6/raw_ip6.c

@@ -243,6 +243,12 @@ rip6_input(struct mbuf **mp, int *offp, int proto)
 			    in6_cksum(m, proto, *offp,
 			    m->m_pkthdr.len - *offp)) {
 				RIP6STAT_INC(rip6s_badsum);
+				/*
+				 * Drop the received message, don't send an
+				 * ICMP6 message. Set proto to IPPROTO_NONE
+				 * to achieve that.
+				 */
+				proto = IPPROTO_NONE;
 				goto skip_2;
 			}
 		}