virtio_net: validate ethtool port setting and explain the user validation

Nikolay Aleksandrov · davem330 · commit 0cf3ace9e7cb · 2016-02-11T11:55:38.000-05:00
We should validate the port setting that we got from the user and check
if it's what we've set it to (PORT_OTHER), also add explanation that
ignoring advertising is good as long as we don't have autonegotiation.

Signed-off-by: Nikolay Aleksandrov &lt;nikolay@cumulusnetworks.com&gt;
Acked-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
@@ -1386,11 +1386,13 @@ static bool virtnet_validate_ethtool_cmd(const struct ethtool_cmd *cmd)
 	struct ethtool_cmd diff1 = *cmd;
 	struct ethtool_cmd diff2 = {};
 
-	/* advertising and cmd are usually set, ignore port because we set it */
+	/* cmd is always set so we need to clear it, validate the port type
+	 * and also without autonegotiation we can ignore advertising
+	 */
 	ethtool_cmd_speed_set(&diff1, 0);
+	diff2.port = PORT_OTHER;
 	diff1.advertising = 0;
 	diff1.duplex = 0;
-	diff1.port = 0;
 	diff1.cmd = 0;
 
 	return !memcmp(&diff1, &diff2, sizeof(diff1));
