Index: head/sys/netinet/tcp_stacks/rack.c
===================================================================
--- head/sys/netinet/tcp_stacks/rack.c
+++ head/sys/netinet/tcp_stacks/rack.c
@@ -7840,7 +7840,16 @@
 		hdrlen += sizeof(struct udphdr);
 	}
 #endif
-	ipoptlen = 0;
+#ifdef INET6
+	if (isipv6)
+		ipoptlen = ip6_optlen(tp->t_inpcb);
+	else
+#endif
+	if (tp->t_inpcb->inp_options)
+		ipoptlen = tp->t_inpcb->inp_options->m_len -
+		    offsetof(struct ipoption, ipopt_list);
+	else
+		ipoptlen = 0;
 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
 	ipoptlen += ipsec_optlen;
 #endif
@@ -7913,6 +7922,18 @@
 				sendalot = 1;
 
 		} else {
+			if (optlen + ipoptlen > tp->t_maxseg) {
+				/*
+				 * Since we don't have enough space to put
+				 * the IP header chain and the TCP header in
+				 * one packet as required by RFC 7112, don't
+				 * send it.
+				 */
+				SOCKBUF_UNLOCK(&so->so_snd);
+				error = EMSGSIZE;
+				sack_rxmit = 0;
+				goto out;
+			}
 			len = tp->t_maxseg - optlen - ipoptlen;
 			sendalot = 1;
 		}
@@ -8414,15 +8435,9 @@
 		m->m_pkthdr.csum_flags |= CSUM_TSO;
 		m->m_pkthdr.tso_segsz = tp->t_maxseg - optlen;
 	}
-#if defined(IPSEC) || defined(IPSEC_SUPPORT)
-	KASSERT(len + hdrlen + ipoptlen - ipsec_optlen == m_length(m, NULL),
-	    ("%s: mbuf chain shorter than expected: %d + %u + %u - %u != %u",
-	    __func__, len, hdrlen, ipoptlen, ipsec_optlen, m_length(m, NULL)));
-#else
-	KASSERT(len + hdrlen + ipoptlen == m_length(m, NULL),
-	    ("%s: mbuf chain shorter than expected: %d + %u + %u != %u",
-	    __func__, len, hdrlen, ipoptlen, m_length(m, NULL)));
-#endif
+	KASSERT(len + hdrlen == m_length(m, NULL),
+	    ("%s: mbuf chain different than expected: %d + %u != %u",
+	    __func__, len, hdrlen, m_length(m, NULL)));
 
 #ifdef TCP_HHOOK
 	/* Run HHOOK_TCP_ESTABLISHED_OUT helper hooks. */