Subject: [PATCH 08/38] net-sysfs: Call dev_hold always in netdev_queue_add_kobject

From: Jouni Hogander <[email-masked]>
Date: Thu, 5 Dec 2019 15:57:07 +0200

[ Upstream commit e0b60903b434a7ee21ba8d8659f207ed84101e89 ]

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 <[email-masked]>
Cc: Tetsuo Handa <[email-masked]>
Cc: David Miller <[email-masked]>
Cc: Lukas Bulwahn <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 net/core/net-sysfs.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index ae3bcb1540ec..5c4624298996 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1459,14 +1459,17 @@ static int netdev_queue_add_kobject(struct net_device *dev, 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 = dev->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)
-- 
2.20.1