ethtool: ioctl: Use array_size() in copy_to_user()

Use array_size() helper instead of the open-coded version in
copy_to_user(). These sorts of multiplication factors need to
be wrapped in array_size().

This issue was found with the help of Coccinelle and, audited and fixed
manually.

Addresses-KSPP-ID: https://github.com/KSPP/linux/issues/83Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ethtool/ioctl.c

@@ -1918,7 +1918,7 @@ static int ethtool_get_stats(struct net_device *dev, void __user *useraddr)
 	if (copy_to_user(useraddr, &stats, sizeof(stats)))
 		goto out;
 	useraddr += sizeof(stats);
-	if (n_stats && copy_to_user(useraddr, data, n_stats * sizeof(u64)))
+	if (n_stats && copy_to_user(useraddr, data, array_size(n_stats, sizeof(u64))))
 		goto out;
 	ret = 0;
 
@@ -1973,7 +1973,7 @@ static int ethtool_get_phy_stats(struct net_device *dev, void __user *useraddr)
 	if (copy_to_user(useraddr, &stats, sizeof(stats)))
 		goto out;
 	useraddr += sizeof(stats);
-	if (n_stats && copy_to_user(useraddr, data, n_stats * sizeof(u64)))
+	if (n_stats && copy_to_user(useraddr, data, array_size(n_stats, sizeof(u64))))
 		goto out;
 	ret = 0;