net-sysfs: Call dev_hold always in netdev_queue_add_kobject

commit e0b60903b434a7ee21ba8d8659f207ed84101e89 upstream.

Dev_hold has to be called always in netdev_queue_add_kobject.
Otherwise usage count drops below 0 in case of failure in
kobject_init_and_add.

Fixes: b8eb718348b8 ("net-sysfs: Fix reference count leak in rx|netdev_queue_add_kobject")
Reported-by: Hulk Robot <hulkci@huawei.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: David Miller <davem@davemloft.net>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 65019647f72ae52f292f82c1fb72d342921698c7..e4fcfe407d5c79d722a147d83a32d0004771476d 100644 (file)
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1143,14 +1143,17 @@ static int netdev_queue_add_kobject(struct net_device *net, int index)
        struct kobject *kobj = &queue->kobj;
        int error = 0;
 
+       /* Kobject_put later will trigger netdev_queue_release call
+        * which decreases dev refcount: Take that reference here
+        */
+       dev_hold(queue->dev);
+
        kobj->kset = net->queues_kset;
        error = kobject_init_and_add(kobj, &netdev_queue_ktype, NULL,
            "tx-%u", index);
        if (error)
                goto err;
 
-       dev_hold(queue->dev);
-
 #ifdef CONFIG_BQL
        error = sysfs_create_group(kobj, &dql_group);
        if (error)