[PATCH 5.4 010/434] net-sysfs: Call dev_hold always in rx_queue_add_kobject

Greg Kroah-Hartman
2019-12-29T17:41:45Z

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

[ 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 <syzbot+30209ea299c09d8785c9@syzkaller.appspotmail.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: Jouni Hogander <jouni.hogander@unikie.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/core/net-sysfs.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -919,14 +919,17 @@ static int rx_queue_add_kobject(struct n
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)