net: ethernet: mtk_eth_soc: out of bounds read in mtk_hwlro_get_fdir_entry()

[ Upstream commit e7e7104e2d ]

The "fsp->location" variable comes from user via ethtool_get_rxnfc().
Check that it is valid to prevent an out of bounds read.

Fixes: 7aab747e55 ("net: ethernet: mediatek: add ethtool functions to configure RX flows of HW LRO")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/net/ethernet/mediatek/mtk_eth_soc.c

@@ -1991,6 +1991,9 @@ static int mtk_hwlro_get_fdir_entry(struct net_device *dev,
 	struct ethtool_rx_flow_spec *fsp =
 		(struct ethtool_rx_flow_spec *)&cmd->fs;
 
+	if (fsp->location >= ARRAY_SIZE(mac->hwlro_ip))
+		return -EINVAL;
+
 	/* only tcp dst ipv4 is meaningful, others are meaningless */
 	fsp->flow_type = TCP_V4_FLOW;
 	fsp->h_u.tcp_ip4_spec.ip4dst = ntohl(mac->hwlro_ip[fsp->location]);