diff --git a/hw/net/vmxnet3.c b/hw/net/vmxnet3.c
index 41f796a247..f65af4e9ef 100644
--- a/hw/net/vmxnet3.c
+++ b/hw/net/vmxnet3.c
@@ -1441,6 +1441,7 @@ static void vmxnet3_activate_device(VMXNET3State *s)
     vmxnet3_setup_rx_filtering(s);
     /* Cache fields from shared memory */
     s->mtu = VMXNET3_READ_DRV_SHARED32(d, s->drv_shmem, devRead.misc.mtu);
+    assert(VMXNET3_MIN_MTU <= s->mtu && s->mtu < VMXNET3_MAX_MTU);
     VMW_CFPRN("MTU is %u", s->mtu);
 
     s->max_rx_frags =
@@ -1486,6 +1487,9 @@ static void vmxnet3_activate_device(VMXNET3State *s)
         /* Read rings memory locations for TX queues */
         pa = VMXNET3_READ_TX_QUEUE_DESCR64(d, qdescr_pa, conf.txRingBasePA);
         size = VMXNET3_READ_TX_QUEUE_DESCR32(d, qdescr_pa, conf.txRingSize);
+        if (size > VMXNET3_TX_RING_MAX_SIZE) {
+            size = VMXNET3_TX_RING_MAX_SIZE;
+        }
 
         vmxnet3_ring_init(d, &s->txq_descr[i].tx_ring, pa, size,
                           sizeof(struct Vmxnet3_TxDesc), false);
@@ -1496,6 +1500,9 @@ static void vmxnet3_activate_device(VMXNET3State *s)
         /* TXC ring */
         pa = VMXNET3_READ_TX_QUEUE_DESCR64(d, qdescr_pa, conf.compRingBasePA);
         size = VMXNET3_READ_TX_QUEUE_DESCR32(d, qdescr_pa, conf.compRingSize);
+        if (size > VMXNET3_TC_RING_MAX_SIZE) {
+            size = VMXNET3_TC_RING_MAX_SIZE;
+        }
         vmxnet3_ring_init(d, &s->txq_descr[i].comp_ring, pa, size,
                           sizeof(struct Vmxnet3_TxCompDesc), true);
         VMXNET3_RING_DUMP(VMW_CFPRN, "TXC", i, &s->txq_descr[i].comp_ring);
@@ -1537,6 +1544,9 @@ static void vmxnet3_activate_device(VMXNET3State *s)
             /* RX rings */
             pa = VMXNET3_READ_RX_QUEUE_DESCR64(d, qd_pa, conf.rxRingBasePA[j]);
             size = VMXNET3_READ_RX_QUEUE_DESCR32(d, qd_pa, conf.rxRingSize[j]);
+            if (size > VMXNET3_RX_RING_MAX_SIZE) {
+                size = VMXNET3_RX_RING_MAX_SIZE;
+            }
             vmxnet3_ring_init(d, &s->rxq_descr[i].rx_ring[j], pa, size,
                               sizeof(struct Vmxnet3_RxDesc), false);
             VMW_CFPRN("RX queue %d:%d: Base: %" PRIx64 ", Size: %d",
@@ -1546,6 +1556,9 @@ static void vmxnet3_activate_device(VMXNET3State *s)
         /* RXC ring */
         pa = VMXNET3_READ_RX_QUEUE_DESCR64(d, qd_pa, conf.compRingBasePA);
         size = VMXNET3_READ_RX_QUEUE_DESCR32(d, qd_pa, conf.compRingSize);
+        if (size > VMXNET3_RC_RING_MAX_SIZE) {
+            size = VMXNET3_RC_RING_MAX_SIZE;
+        }
         vmxnet3_ring_init(d, &s->rxq_descr[i].comp_ring, pa, size,
                           sizeof(struct Vmxnet3_RxCompDesc), true);
         VMW_CFPRN("RXC queue %d: Base: %" PRIx64 ", Size: %d", i, pa, size);
diff --git a/net/colo-compare.c b/net/colo-compare.c
index b8876d7fd9..b966e7e514 100644
--- a/net/colo-compare.c
+++ b/net/colo-compare.c
@@ -209,7 +209,8 @@ static void fill_pkt_tcp_info(void *data, uint32_t *max_ack)
 
     pkt->tcp_seq = ntohl(tcphd->th_seq);
     pkt->tcp_ack = ntohl(tcphd->th_ack);
-    *max_ack = *max_ack > pkt->tcp_ack ? *max_ack : pkt->tcp_ack;
+    /* Need to consider ACK will bigger than uint32_t MAX */
+    *max_ack = pkt->tcp_ack - *max_ack > 0 ? pkt->tcp_ack : *max_ack;
     pkt->header_size = pkt->transport_header - (uint8_t *)pkt->data
                        + (tcphd->th_off << 2);
     pkt->payload_size = pkt->size - pkt->header_size;
@@ -413,7 +414,8 @@ static void colo_compare_tcp(CompareState *s, Connection *conn)
      * can ensure that the packet's payload is acknowledged by
      * primary and secondary.
     */
-    uint32_t min_ack = conn->pack > conn->sack ? conn->sack : conn->pack;
+    uint32_t min_ack = conn->pack - conn->sack > 0 ?
+                       conn->sack : conn->pack;
 
 pri:
     if (g_queue_is_empty(&conn->primary_list)) {
@@ -805,7 +807,7 @@ static int compare_chr_send(CompareState *s,
     }
 
     if (!size) {
-        return 0;
+        return -1;
     }
 
     entry = g_slice_new(SendEntry);