bonding: fix length of actor system

BugLink: https://bugs.launchpad.net/bugs/1878232

commit 414dd6fb upstream.

The attribute IFLA_BOND_AD_ACTOR_SYSTEM is sent to user space having the
length of sizeof(bond->params.ad_actor_system) which is 8 byte. This
patch aligns the length to ETH_ALEN to have the same MAC address exposed
as using sysfs.

Fixes: f87fda00 ("bonding: prevent out of bound accesses")
Signed-off-by: Tobias Jungel <tobias.jungel@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ian May <ian.may@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/net/bonding/bond_netlink.c

@@ -628,8 +628,7 @@ static int bond_fill_info(struct sk_buff *skb,
 				goto nla_put_failure;
 
 			if (nla_put(skb, IFLA_BOND_AD_ACTOR_SYSTEM,
-				    sizeof(bond->params.ad_actor_system),
-				    &bond->params.ad_actor_system))
+				    ETH_ALEN, &bond->params.ad_actor_system))
 				goto nla_put_failure;
 		}
 		if (!bond_3ad_get_active_agg_info(bond, &info)) {