[PATCH 5.4 099/102] net-sysfs: Call dev_hold always in netdev_queue_add_kobject

Greg Kroah-Hartman
2020-01-24T09:43:24Z

From: Jouni Hogander <jouni.hogander@unikie.com>

[ 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 <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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 b4db68e5caa9a..4c826b8bf9b1e 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -1462,14 +1462,17 @@ 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