net-sysfs: Fix memory leak in XPS configuration

[ Upstream commit 664088f8 ]

This patch reorders the error cases in showing the XPS configuration so
that we hold off on memory allocation until after we have verified that we
can support XPS on a given ring.

Fixes: 184c449f ("net: Add support for XPS with QoS via traffic classes")
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

net/core/net-sysfs.c

@@ -1207,9 +1207,6 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 	cpumask_var_t mask;
 	unsigned long index;
 
-	if (!zalloc_cpumask_var(&mask, GFP_KERNEL))
-		return -ENOMEM;
-
 	index = get_netdev_queue_index(queue);
 
 	if (dev->num_tc) {
@@ -1219,6 +1216,9 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue,
 			return -EINVAL;
 	}
 
+	if (!zalloc_cpumask_var(&mask, GFP_KERNEL))
+		return -ENOMEM;
+
 	rcu_read_lock();
 	dev_maps = rcu_dereference(dev->xps_maps);
 	if (dev_maps) {