Index: head/sys/dev/hyperv/include/vmbus.h
===================================================================
--- head/sys/dev/hyperv/include/vmbus.h
+++ head/sys/dev/hyperv/include/vmbus.h
@@ -102,9 +102,6 @@
 	struct vmbus_rxbuf_desc cp_rxbuf[];
 } __packed;
 
-#define VMBUS_CHAN_SGLIST_MAX		32
-#define VMBUS_CHAN_PRPLIST_MAX		32
-
 struct vmbus_channel;
 struct hyperv_guid;
 
Index: head/sys/dev/hyperv/netvsc/hv_net_vsc.h
===================================================================
--- head/sys/dev/hyperv/netvsc/hv_net_vsc.h
+++ head/sys/dev/hyperv/netvsc/hv_net_vsc.h
@@ -1088,6 +1088,7 @@
 typedef void (*pfn_on_send_rx_completion)(struct vmbus_channel *, void *);
 
 #define NETVSC_DEVICE_RING_BUFFER_SIZE	(128 * PAGE_SIZE)
+#define NETVSC_PACKET_MAXPAGE		32
 
 #define NETVSC_VLAN_PRIO_MASK		0xe000
 #define NETVSC_VLAN_PRIO_SHIFT		13
@@ -1137,7 +1138,7 @@
 	uint32_t	tot_data_buf_len;
 	void		*data;
 	uint32_t	gpa_cnt;
-	struct vmbus_gpa gpa[VMBUS_CHAN_SGLIST_MAX];
+	struct vmbus_gpa gpa[NETVSC_PACKET_MAXPAGE];
 } netvsc_packet;
 
 typedef struct {
Index: head/sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c
===================================================================
--- head/sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c
+++ head/sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c
@@ -152,7 +152,7 @@
 #define HN_TX_DATA_MAXSIZE		IP_MAXPACKET
 #define HN_TX_DATA_SEGSIZE		PAGE_SIZE
 #define HN_TX_DATA_SEGCNT_MAX		\
-    (VMBUS_CHAN_SGLIST_MAX - HV_RF_NUM_TX_RESERVED_PAGE_BUFS)
+    (NETVSC_PACKET_MAXPAGE - HV_RF_NUM_TX_RESERVED_PAGE_BUFS)
 
 #define HN_DIRECT_TX_SIZE_DEF		128
 
Index: head/sys/dev/hyperv/storvsc/hv_storvsc_drv_freebsd.c
===================================================================
--- head/sys/dev/hyperv/storvsc/hv_storvsc_drv_freebsd.c
+++ head/sys/dev/hyperv/storvsc/hv_storvsc_drv_freebsd.c
@@ -88,7 +88,7 @@
 
 #define VSTOR_PKT_SIZE	(sizeof(struct vstor_packet) - vmscsi_size_delta)
 
-#define STORVSC_DATA_SEGCNT_MAX		VMBUS_CHAN_PRPLIST_MAX
+#define STORVSC_DATA_SEGCNT_MAX		32
 #define STORVSC_DATA_SEGSZ_MAX		PAGE_SIZE
 #define STORVSC_DATA_SIZE_MAX		\
 	(STORVSC_DATA_SEGCNT_MAX * STORVSC_DATA_SEGSZ_MAX)
Index: head/sys/dev/hyperv/vmbus/vmbus_brvar.h
===================================================================
--- head/sys/dev/hyperv/vmbus/vmbus_brvar.h
+++ head/sys/dev/hyperv/vmbus/vmbus_brvar.h
@@ -71,6 +71,13 @@
 struct sysctl_ctx_list;
 struct sysctl_oid;
 
+static __inline int
+vmbus_txbr_maxpktsz(const struct vmbus_txbr *tbr)
+{
+	/* 1/2 data size */
+	return (tbr->txbr_dsize / 2);
+}
+
 void		vmbus_br_sysctl_create(struct sysctl_ctx_list *ctx,
 		    struct sysctl_oid *br_tree, struct vmbus_br *br,
 		    const char *name);
Index: head/sys/dev/hyperv/vmbus/vmbus_chan.c
===================================================================
--- head/sys/dev/hyperv/vmbus/vmbus_chan.c
+++ head/sys/dev/hyperv/vmbus/vmbus_chan.c
@@ -610,6 +610,8 @@
 	hlen = sizeof(pkt);
 	pktlen = hlen + dlen;
 	pad_pktlen = VMBUS_CHANPKT_TOTLEN(pktlen);
+	KASSERT(pad_pktlen <= vmbus_txbr_maxpktsz(&chan->ch_txbr),
+	    ("invalid packet size %d", pad_pktlen));
 
 	pkt.cp_hdr.cph_type = type;
 	pkt.cp_hdr.cph_flags = flags;
@@ -640,12 +642,11 @@
 	boolean_t send_evt;
 	uint64_t pad = 0;
 
-	KASSERT(sglen < VMBUS_CHAN_SGLIST_MAX,
-	    ("invalid sglist len %d", sglen));
-
 	hlen = __offsetof(struct vmbus_chanpkt_sglist, cp_gpa[sglen]);
 	pktlen = hlen + dlen;
 	pad_pktlen = VMBUS_CHANPKT_TOTLEN(pktlen);
+	KASSERT(pad_pktlen <= vmbus_txbr_maxpktsz(&chan->ch_txbr),
+	    ("invalid packet size %d", pad_pktlen));
 
 	pkt.cp_hdr.cph_type = VMBUS_CHANPKT_TYPE_GPA;
 	pkt.cp_hdr.cph_flags = VMBUS_CHANPKT_FLAG_RC;
@@ -681,13 +682,12 @@
 	boolean_t send_evt;
 	uint64_t pad = 0;
 
-	KASSERT(prp_cnt < VMBUS_CHAN_PRPLIST_MAX,
-	    ("invalid prplist entry count %d", prp_cnt));
-
 	hlen = __offsetof(struct vmbus_chanpkt_prplist,
 	    cp_range[0].gpa_page[prp_cnt]);
 	pktlen = hlen + dlen;
 	pad_pktlen = VMBUS_CHANPKT_TOTLEN(pktlen);
+	KASSERT(pad_pktlen <= vmbus_txbr_maxpktsz(&chan->ch_txbr),
+	    ("invalid packet size %d", pad_pktlen));
 
 	pkt.cp_hdr.cph_type = VMBUS_CHANPKT_TYPE_GPA;
 	pkt.cp_hdr.cph_flags = VMBUS_CHANPKT_FLAG_RC;