iavf: validate pointers

In some cases, the ethtool get_rxfh handler may be called with a null
key or indir parameter. So check these pointers, or you will have a very
bad day.

Fixes: 43a3d9ba ("i40evf: Allow PF driver to configure RSS")
Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Tested-by: Tony Brelinski <tony.brelinski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/iavf/iavf_ethtool.c

@@ -1859,14 +1859,13 @@ static int iavf_get_rxfh(struct net_device *netdev, u32 *indir, u8 *key,
 
 	if (hfunc)
 		*hfunc = ETH_RSS_HASH_TOP;
-	if (!indir)
-		return 0;
-
-	memcpy(key, adapter->rss_key, adapter->rss_key_size);
+	if (key)
+		memcpy(key, adapter->rss_key, adapter->rss_key_size);
 
-	/* Each 32 bits pointed by 'indir' is stored with a lut entry */
-	for (i = 0; i < adapter->rss_lut_size; i++)
-		indir[i] = (u32)adapter->rss_lut[i];
+	if (indir)
+		/* Each 32 bits pointed by 'indir' is stored with a lut entry */
+		for (i = 0; i < adapter->rss_lut_size; i++)
+			indir[i] = (u32)adapter->rss_lut[i];
 
 	return 0;
 }