net: stmmac: Do not accept invalid MTU values

joabreu · davem330 · commit eaf4fac47807 · 2019-12-18T12:04:17.000-08:00
The maximum MTU value is determined by the maximum size of TX FIFO so that a full packet can fit in the FIFO. Add a check for this in the MTU change callback. Also check if provided and rounded MTU does not passes the maximum limit of 16K. Changes from v2: - Align MTU before checking if its valid Fixes: 7ac6653 ("stmmac: Move the STMicroelectronics driver") Signed-off-by: Jose Abreu <Jose.Abreu@synopsys.com> Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -3827,12 +3827,24 @@ static void stmmac_set_rx_mode(struct net_device *dev)
 static int stmmac_change_mtu(struct net_device *dev, int new_mtu)
 {
 	struct stmmac_priv *priv = netdev_priv(dev);
+	int txfifosz = priv->plat->tx_fifo_size;
+
+	if (txfifosz == 0)
+		txfifosz = priv->dma_cap.tx_fifo_size;
+
+	txfifosz /= priv->plat->tx_queues_to_use;
 
 	if (netif_running(dev)) {
 		netdev_err(priv->dev, "must be stopped to change its MTU\n");
 		return -EBUSY;
 	}
 
+	new_mtu = STMMAC_ALIGN(new_mtu);
+
+	/* If condition true, FIFO is too small or MTU too large */
+	if ((txfifosz < new_mtu) || (new_mtu > BUF_SIZE_16KiB))
+		return -EINVAL;
+
 	dev->mtu = new_mtu;
 
 	netdev_update_features(dev);
