r8169: add check for PHY_MDIO_CHG to rtl_nic_fw_data_ok

Only values 0 and 1 are currently defined as parameters for
PHY_MDIO_CHG. Instead of silently ignoring unknown values and
misinterpreting the firmware code let's explicitly check.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/realtek/r8169_firmware.c

@@ -92,19 +92,24 @@ static bool rtl_fw_data_ok(struct rtl_fw *rtl_fw)
 
 	for (index = 0; index < pa->size; index++) {
 		u32 action = le32_to_cpu(pa->code[index]);
+		u32 val = action & 0x0000ffff;
 		u32 regno = (action & 0x0fff0000) >> 16;
 
 		switch (action >> 28) {
 		case PHY_READ:
 		case PHY_DATA_OR:
 		case PHY_DATA_AND:
-		case PHY_MDIO_CHG:
 		case PHY_CLEAR_READCOUNT:
 		case PHY_WRITE:
 		case PHY_WRITE_PREVIOUS:
 		case PHY_DELAY_MS:
 			break;
 
+		case PHY_MDIO_CHG:
+			if (val > 1)
+				goto out;
+			break;
+
 		case PHY_BJMPN:
 			if (regno > index)
 				goto out;
@@ -164,12 +169,12 @@ void rtl_fw_write_firmware(struct rtl8169_private *tp, struct rtl_fw *rtl_fw)
 			index -= (regno + 1);
 			break;
 		case PHY_MDIO_CHG:
-			if (data == 0) {
-				fw_write = rtl_fw->phy_write;
-				fw_read = rtl_fw->phy_read;
-			} else if (data == 1) {
+			if (data) {
 				fw_write = rtl_fw->mac_mcu_write;
 				fw_read = rtl_fw->mac_mcu_read;
+			} else {
+				fw_write = rtl_fw->phy_write;
+				fw_read = rtl_fw->phy_read;
 			}
 
 			break;