Subject: [PATCH 10/27] net-sysfs: Call dev_hold always in rx_queue_add_kobject

From: Jouni Hogander <[email-masked]>
Date: Tue, 17 Dec 2019 13:46:34 +0200

[ Upstream commit ddd9b5e3e765d8ed5a35786a6cb00111713fe161 ]

Dev_hold has to be called always in rx_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: syzbot <[email-masked]>
Cc: Tetsuo Handa <[email-masked]>
Cc: David Miller <[email-masked]>
Cc: Lukas Bulwahn <[email-masked]>
Signed-off-by: Jouni Hogander <[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..b4db68e5caa9 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -919,14 +919,17 @@ static int rx_queue_add_kobject(struct net_device *dev, int index)
 	struct kobject *kobj = &queue->kobj;
 	int error = 0;
 
+	/* Kobject_put later will trigger rx_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, &rx_queue_ktype, NULL,
 				     "rx-%u", index);
 	if (error)
 		goto err;
 
-	dev_hold(queue->dev);
-
 	if (dev->sysfs_rx_queue_group) {
 		error = sysfs_create_group(kobj, dev->sysfs_rx_queue_group);
 		if (error)
-- 
2.20.1