1 files changed, 7 insertions, 5 deletions

diff --git a/sys/netinet6/udp6_usrreq.c b/sys/netinet6/udp6_usrreq.c
index 64e5f6e3551fa..124bded74a404 100644
--- a/sys/netinet6/udp6_usrreq.c
+++ b/sys/netinet6/udp6_usrreq.c
@@ -223,11 +223,13 @@ udp6_input(struct mbuf **mp, int *offp, int proto)
 
 	ifp = m->m_pkthdr.rcvif;
 
-	m = m_pullup(m, off + sizeof(struct udphdr));
-	if (m == NULL) {
-		IP6STAT_INC(ip6s_exthdrtoolong);
-		*mp = NULL;
-		return (IPPROTO_DONE);
+	if (m->m_len < off + sizeof(struct udphdr)) {
+		m = m_pullup(m, off + sizeof(struct udphdr));
+		if (m == NULL) {
+			IP6STAT_INC(ip6s_exthdrtoolong);
+			*mp = NULL;
+			return (IPPROTO_DONE);
+		}
 	}
 	ip6 = mtod(m, struct ip6_hdr *);
 	uh = (struct udphdr *)((caddr_t)ip6 + off);