diff -r 4ea51bc8a05d -r 4a99aed41584 sys/dev/cxgbe/adapter.h
--- a/sys/dev/cxgbe/adapter.h	Mon Jun 29 18:06:47 2015 -0700
+++ b/sys/dev/cxgbe/adapter.h	Thu Jul 02 14:57:05 2015 -0700
@@ -326,6 +326,9 @@ struct tx_desc {
 struct tx_sdesc {
 	struct mbuf *m;		/* m_nextpkt linked chain of frames */
 	uint8_t desc_used;	/* # of hardware descriptors used by the WR */
+#if 1
+	uint8_t header_mbuf[MSIZE] __aligned(256);
+#endif
 };
 
 
diff -r 4ea51bc8a05d -r 4a99aed41584 sys/dev/cxgbe/t4_sge.c
--- a/sys/dev/cxgbe/t4_sge.c	Mon Jun 29 18:06:47 2015 -0700
+++ b/sys/dev/cxgbe/t4_sge.c	Thu Jul 02 14:57:05 2015 -0700
@@ -2450,10 +2450,10 @@ eth_tx(struct mp_ring *r, u_int cidx, u_
 			total += txp.npkt;
 			remaining -= txp.npkt;
 		} else {
+			ETHER_BPF_MTAP(ifp, m0);
+			n = write_txpkt_wr(txq, (void *)wr, m0, available);
 			total++;
 			remaining--;
-			n = write_txpkt_wr(txq, (void *)wr, m0, available);
-			ETHER_BPF_MTAP(ifp, m0);
 		}
 		MPASS(n >= 1 && n <= available && n <= SGE_MAX_WR_NDESC);
 
@@ -4060,6 +4060,17 @@ write_txpkt_wr(struct sge_txq *txq, stru
 	txsd = &txq->sdesc[eq->pidx];
 	txsd->m = m0;
 	txsd->desc_used = ndesc;
+#if 1
+	/*
+	 * Save a copy of the entire mbuf and then zero out the headers to catch
+	 * others that try and use this mbuf.
+	 */
+	bcopy(m0, &txsd->header_mbuf[0], MSIZE);
+	if (m0->m_flags & M_EXT)
+		bzero(m0, MSIZE);
+	else
+		bzero(m0, offsetof(struct mbuf, m_pktdat[0]));
+#endif
 
 	return (ndesc);
 }
@@ -4240,6 +4251,13 @@ write_txpkts_wr(struct sge_txq *txq, str
 	txsd = &txq->sdesc[eq->pidx];
 	txsd->m = m0;
 	txsd->desc_used = ndesc;
+#if 1
+	bcopy(m0, &txsd->header_mbuf[0], MSIZE);
+	if (m0->m_flags & M_EXT)
+		bzero(m0, MSIZE);
+	else
+		bzero(m0, offsetof(struct mbuf, m_pktdat[0]));
+#endif
 
 	return (ndesc);
 }
@@ -4451,6 +4469,10 @@ reclaim_tx_descs(struct sge_txq *txq, u_
 		txsd = &txq->sdesc[eq->cidx];
 		ndesc = txsd->desc_used;
 
+#if 1
+		bcopy(&txsd->header_mbuf[0], txsd->m, MSIZE);
+#endif
+
 		/* Firmware doesn't return "partial" credits. */
 		KASSERT(can_reclaim >= ndesc,
 		    ("%s: unexpected number of credits: %d, %d",