Index: net/if_etherip.c
===================================================================
RCS file: /cvs/src/sys/net/if_etherip.c,v
retrieving revision 1.7
diff -u -p -r1.7 if_etherip.c
--- net/if_etherip.c	13 Apr 2016 11:41:15 -0000	1.7
+++ net/if_etherip.c	10 Oct 2016 04:06:11 -0000
@@ -368,26 +368,14 @@ ip_etherip_output(struct ifnet *ifp, str
 		return ENETUNREACH;
 	}
 
-	m->m_flags &= ~(M_BCAST|M_MCAST);
-
-	M_PREPEND(m, sizeof(struct etherip_header), M_DONTWAIT);
-	if (m == NULL) {
-		etheripstat.etherip_adrops++;
-		return ENOBUFS;
-	}
-	eip = mtod(m, struct etherip_header *);
-	eip->eip_ver = ETHERIP_VERSION;
-	eip->eip_res = 0;
-	eip->eip_pad = 0;
-
-	M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
+	M_PREPEND(m, sizeof(*ip) + sizeof(*eip), M_DONTWAIT);
 	if (m == NULL) {
 		etheripstat.etherip_adrops++;
 		return ENOBUFS;
 	}
 	ip = mtod(m, struct ip *);
-	memset(ip, 0, sizeof(struct ip));
 
+	memset(ip, 0, sizeof(struct ip));
 	ip->ip_v = IPVERSION;
 	ip->ip_hl = sizeof(struct ip) >> 2;
 	ip->ip_id = htons(ip_randomid());
@@ -398,6 +386,12 @@ ip_etherip_output(struct ifnet *ifp, str
 	ip->ip_src = src->sin_addr;
 	ip->ip_dst = dst->sin_addr;
 
+	eip = (struct etherip_header *)(ip + 1);
+	eip->eip_ver = ETHERIP_VERSION;
+	eip->eip_res = 0;
+	eip->eip_pad = 0;
+
+	m->m_flags &= ~(M_BCAST|M_MCAST);
 	m->m_pkthdr.ph_rtableid = sc->sc_rdomain;
 
 #if NPF > 0