Index: sys/netipsec/ipsec_output.c
===================================================================
--- sys/netipsec/ipsec_output.c
+++ sys/netipsec/ipsec_output.c
@@ -323,14 +323,22 @@
 		 * this is done in the normal processing path.
 		 */
 		if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
+			m = mb_unmapped_to_ext(m);
+			if (m == NULL) {
+				IPSECSTAT_INC(ips_out_nomem);
+				return (ENOBUFS);
+			}
 			in_delayed_cksum(m);
 			m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
 		}
 #if defined(SCTP) || defined(SCTP_SUPPORT)
 		if (m->m_pkthdr.csum_flags & CSUM_SCTP) {
-			struct ip *ip = mtod(m, struct ip *);
-
-			sctp_delayed_cksum(m, (uint32_t)(ip->ip_hl << 2));
+			m = mb_unmapped_to_ext(m);
+			if (m == NULL) {
+				IPSECSTAT_INC(ips_out_nomem);
+				return (ENOBUFS);
+			}
+			sctp_delayed_cksum(m, mtod(m, struct ip *)->ip_hl << 2);
 			m->m_pkthdr.csum_flags &= ~CSUM_SCTP;
 		}
 #endif