net/igb/e1000/e1000e: more robust ethtool duplex/speed configuration

This makes sure that one cannot request a 99Mbps full-duplex and get a
100Mbps half-duplex configuration in return due to the way the
speed/duplex parameters are handled internally.

Tested: e1000 works
Signed-off-by: David Decotigny <decot@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/e1000e/ethtool.c b/drivers/net/e1000e/ethtool.c
index 12f1ee2..859d0d3 100644
--- a/drivers/net/e1000e/ethtool.c
+++ b/drivers/net/e1000e/ethtool.c
@@ -200,20 +200,25 @@
 	return 0;
 }
 
-static int e1000_set_spd_dplx(struct e1000_adapter *adapter, u16 spddplx)
+static int e1000_set_spd_dplx(struct e1000_adapter *adapter, u32 spd, u8 dplx)
 {
 	struct e1000_mac_info *mac = &adapter->hw.mac;
 
 	mac->autoneg = 0;
 
+	/* Make sure dplx is at most 1 bit and lsb of speed is not set
+	 * for the switch() below to work */
+	if ((spd & 1) || (dplx & ~1))
+		goto err_inval;
+
 	/* Fiber NICs only allow 1000 gbps Full duplex */
 	if ((adapter->hw.phy.media_type == e1000_media_type_fiber) &&
-		spddplx != (SPEED_1000 + DUPLEX_FULL)) {
-		e_err("Unsupported Speed/Duplex configuration\n");
-		return -EINVAL;
+	    spd != SPEED_1000 &&
+	    dplx != DUPLEX_FULL) {
+		goto err_inval;
 	}
 
-	switch (spddplx) {
+	switch (spd + dplx) {
 	case SPEED_10 + DUPLEX_HALF:
 		mac->forced_speed_duplex = ADVERTISE_10_HALF;
 		break;
@@ -232,10 +237,13 @@
 		break;
 	case SPEED_1000 + DUPLEX_HALF: /* not supported */
 	default:
-		e_err("Unsupported Speed/Duplex configuration\n");
-		return -EINVAL;
+		goto err_inval;
 	}
 	return 0;
+
+err_inval:
+	e_err("Unsupported Speed/Duplex configuration\n");
+	return -EINVAL;
 }
 
 static int e1000_set_settings(struct net_device *netdev,
@@ -272,7 +280,7 @@
 			hw->fc.requested_mode = e1000_fc_default;
 	} else {
 		u32 speed = ethtool_cmd_speed(ecmd);
-		if (e1000_set_spd_dplx(adapter, speed + ecmd->duplex)) {
+		if (e1000_set_spd_dplx(adapter, speed, ecmd->duplex)) {
 			clear_bit(__E1000_RESETTING, &adapter->state);
 			return -EINVAL;
 		}