octeon_ep: Validate the VF ID

Add a helper to validate the VF ID and use it in the VF ndo ops to
prevent accessing out-of-range entries.

Without this check, users can run commands such as:

# ip link show dev enp135s0
2: enp135s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DEFAULT group default qlen 1000
link/ether 00:00:00:01:01:00 brd ff:ff:ff:ff:ff:ff
vf 0 link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff, spoof checking on, link-state enable, trust off
vf 1 link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff, spoof checking on, link-state enable, trust off
# ip link set dev enp135s0 vf 4 mac 00:00:00:00:00:14
# echo $?
0

even though VF 4 does not exist, which results in silent success instead
of returning an error.

Fixes: 8a241ef9b9b8 ("octeon_ep: add ndo ops for VFs in PF driver")
Signed-off-by: Kamal Heib <[e-mail]>
Reviewed-by: Michal Swiatkowski <[e-mail]>
Reviewed-by: Simon Horman <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/ethernet/marvell/octeon_ep/octep_main.c

···
 	return err;
 }
 
+static bool octep_is_vf_valid(struct octep_device *oct, int vf)
+{
+	if (vf >= CFG_GET_ACTIVE_VFS(oct->conf)) {
+		netdev_err(oct->netdev, "Invalid VF ID %d\n", vf);
+		return false;
+	}
+
+	return true;
+}
+
 static int octep_get_vf_config(struct net_device *dev, int vf,
 			       struct ifla_vf_info *ivi)
 {
 	struct octep_device *oct = netdev_priv(dev);
+
+	if (!octep_is_vf_valid(oct, vf))
+		return -EINVAL;
 
 	ivi->vf = vf;
 	ether_addr_copy(ivi->mac, oct->vf_info[vf].mac_addr);
···
 {
 	struct octep_device *oct = netdev_priv(dev);
 	int err;
+
+	if (!octep_is_vf_valid(oct, vf))
+		return -EINVAL;
 
 	if (!is_valid_ether_addr(mac)) {
 		dev_err(&oct->pdev->dev, "Invalid  MAC Address %pM\n", mac);