RDMA/cma: Do not ignore net namespace for unbound cm_id

Currently if the cm_id is not bound to any netdevice, than for such cm_id,
net namespace is ignored; which is incorrect.

Regardless of cm_id bound to a netdevice or not, net namespace must
match. When a cm_id is bound to a netdevice, in such case net namespace
and netdevice both must match.

Fixes: 4c21b5bc ("IB/cma: Add net_dev and private data checks to RDMA CM")
Signed-off-by: Parav Pandit <parav@mellanox.com>
Reviewed-by: Daniel Jurgens <danielj@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/core/cma.c

@@ -1474,9 +1474,16 @@ static bool cma_match_net_dev(const struct rdma_cm_id *id,
 		return (!id->port_num || id->port_num == port_num) &&
 		       (addr->src_addr.ss_family == AF_IB);
 
-	return !addr->dev_addr.bound_dev_if ||
-	       (net_eq(dev_net(net_dev), addr->dev_addr.net) &&
-		addr->dev_addr.bound_dev_if == net_dev->ifindex);
+	/*
+	 * Net namespaces must match, and if the listner is listening
+	 * on a specific netdevice than netdevice must match as well.
+	 */
+	if (net_eq(dev_net(net_dev), addr->dev_addr.net) &&
+	    (!!addr->dev_addr.bound_dev_if ==
+	     (addr->dev_addr.bound_dev_if == net_dev->ifindex)))
+		return true;
+	else
+		return false;
 }
 
 static struct rdma_id_private *cma_find_listener(