diff --git a/hw/net/net_tx_pkt.c b/hw/net/net_tx_pkt.c
index efd43b47b8..53dfaa292c 100644
--- a/hw/net/net_tx_pkt.c
+++ b/hw/net/net_tx_pkt.c
@@ -590,7 +590,7 @@ static bool net_tx_pkt_do_sw_fragmentation(struct NetTxPkt *pkt,
 
         fragment_offset += fragment_len;
 
-    } while (more_frags);
+    } while (fragment_len && more_frags);
 
     return true;
 }
diff --git a/hw/net/vmxnet3.c b/hw/net/vmxnet3.c
index bbf44adbcc..90f6943668 100644
--- a/hw/net/vmxnet3.c
+++ b/hw/net/vmxnet3.c
@@ -1167,6 +1167,10 @@ vmxnet3_io_bar0_write(void *opaque, hwaddr addr,
 {
     VMXNET3State *s = opaque;
 
+    if (!s->device_active) {
+        return;
+    }
+
     if (VMW_IS_MULTIREG_ADDR(addr, VMXNET3_REG_TXPROD,
                         VMXNET3_DEVICE_MAX_TX_QUEUES, VMXNET3_REG_ALIGN)) {
         int tx_queue_idx =
diff --git a/hw/net/xilinx_ethlite.c b/hw/net/xilinx_ethlite.c
index 54db2b83bd..35de353b7c 100644
--- a/hw/net/xilinx_ethlite.c
+++ b/hw/net/xilinx_ethlite.c
@@ -197,6 +197,10 @@ static ssize_t eth_rx(NetClientState *nc, const uint8_t *buf, size_t size)
     }
 
     D(qemu_log("%s %zd rxbase=%x\n", __func__, size, rxbase));
+    if (size > (R_MAX - R_RX_BUF0 - rxbase) * 4) {
+        D(qemu_log("ethlite packet is too big, size=%x\n", size));
+        return -1;
+    }
     memcpy(&s->regs[rxbase + R_RX_BUF0], buf, size);
 
     s->regs[rxbase + R_RX_CTRL0] |= CTRL_S;