bridge: Netlink interface fix.

This commit is correcting NETLINK br_fill_ifinfo() to be able to
handle 'filter_mask' with multiple flags asserted.

Fixes: 36a8e8e ("bridge: Extend br_fill_ifinfo to return MPR status")

Signed-off-by: Henrik Bjoernlund <henrik.bjoernlund@microchip.com>
Reviewed-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Suggested-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Tested-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Acked-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: HenrikBjoernlund

net/bridge/br_netlink.c

@@ -380,6 +380,7 @@ static int br_fill_ifinfo(struct sk_buff *skb,
 			  u32 filter_mask, const struct net_device *dev)
 {
 	u8 operstate = netif_running(dev) ? dev->operstate : IF_OPER_DOWN;
+	struct nlattr *af = NULL;
 	struct net_bridge *br;
 	struct ifinfomsg *hdr;
 	struct nlmsghdr *nlh;
@@ -423,11 +424,18 @@ static int br_fill_ifinfo(struct sk_buff *skb,
 		nla_nest_end(skb, nest);
 	}
 
+	if (filter_mask & (RTEXT_FILTER_BRVLAN |
+			   RTEXT_FILTER_BRVLAN_COMPRESSED |
+			   RTEXT_FILTER_MRP)) {
+		af = nla_nest_start_noflag(skb, IFLA_AF_SPEC);
+		if (!af)
+			goto nla_put_failure;
+	}
+
 	/* Check if  the VID information is requested */
 	if ((filter_mask & RTEXT_FILTER_BRVLAN) ||
 	    (filter_mask & RTEXT_FILTER_BRVLAN_COMPRESSED)) {
 		struct net_bridge_vlan_group *vg;
-		struct nlattr *af;
 		int err;
 
 		/* RCU needed because of the VLAN locking rules (rcu || rtnl) */
@@ -441,11 +449,6 @@ static int br_fill_ifinfo(struct sk_buff *skb,
 			rcu_read_unlock();
 			goto done;
 		}
-		af = nla_nest_start_noflag(skb, IFLA_AF_SPEC);
-		if (!af) {
-			rcu_read_unlock();
-			goto nla_put_failure;
-		}
 		if (filter_mask & RTEXT_FILTER_BRVLAN_COMPRESSED)
 			err = br_fill_ifvlaninfo_compressed(skb, vg);
 		else
@@ -456,32 +459,25 @@ static int br_fill_ifinfo(struct sk_buff *skb,
 		rcu_read_unlock();
 		if (err)
 			goto nla_put_failure;
-
-		nla_nest_end(skb, af);
 	}
 
 	if (filter_mask & RTEXT_FILTER_MRP) {
-		struct nlattr *af;
 		int err;
 
 		if (!br_mrp_enabled(br) || port)
 			goto done;
 
-		af = nla_nest_start_noflag(skb, IFLA_AF_SPEC);
-		if (!af)
-			goto nla_put_failure;
-
 		rcu_read_lock();
 		err = br_mrp_fill_info(skb, br);
 		rcu_read_unlock();
 
 		if (err)
 			goto nla_put_failure;
-
-		nla_nest_end(skb, af);
 	}
 
 done:
+	if (af)
+		nla_nest_end(skb, af);
 	nlmsg_end(skb, nlh);
 	return 0;