kernel: fix refcnt leak in LED netdev trigger on interface rename
[openwrt/staging/wigyori.git] / target / linux / generic / backport-4.19 / 400-v5.2-leds-trigger-netdev-fix-refcnt-leak-on-interface-ren.patch
1 From dd7590a3ab3f0804ed5e930295e2caa5979e3958 Mon Sep 17 00:00:00 2001
2 From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
3 Date: Thu, 28 Feb 2019 22:57:33 +0100
4 Subject: [PATCH] leds: trigger: netdev: fix refcnt leak on interface rename
5 MIME-Version: 1.0
6 Content-Type: text/plain; charset=UTF-8
7 Content-Transfer-Encoding: 8bit
8
9 Renaming a netdev-trigger-tracked interface was resulting in an
10 unbalanced dev_hold().
11
12 Example:
13 > iw phy phy0 interface add foo type __ap
14 > echo netdev > trigger
15 > echo foo > device_name
16 > ip link set foo name bar
17 > iw dev bar del
18 [ 237.355366] unregister_netdevice: waiting for bar to become free. Usage count = 1
19 [ 247.435362] unregister_netdevice: waiting for bar to become free. Usage count = 1
20 [ 257.545366] unregister_netdevice: waiting for bar to become free. Usage count = 1
21
22 Above problem was caused by trigger checking a dev->name which obviously
23 changes after renaming an interface. It meant missing all further events
24 including the NETDEV_UNREGISTER which is required for calling dev_put().
25
26 This change fixes that by:
27 1) Comparing device struct *address* for notification-filtering purposes
28 2) Dropping unneeded NETDEV_CHANGENAME code (no behavior change)
29
30 Fixes: 06f502f57d0d ("leds: trigger: Introduce a NETDEV trigger")
31 Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
32 Acked-by: Pavel Machek <pavel@ucw.cz>
33 Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
34 ---
35 drivers/leds/trigger/ledtrig-netdev.c | 13 +++++--------
36 1 file changed, 5 insertions(+), 8 deletions(-)
37
38 --- a/drivers/leds/trigger/ledtrig-netdev.c
39 +++ b/drivers/leds/trigger/ledtrig-netdev.c
40 @@ -301,11 +301,11 @@ static int netdev_trig_notify(struct not
41 container_of(nb, struct led_netdev_data, notifier);
42
43 if (evt != NETDEV_UP && evt != NETDEV_DOWN && evt != NETDEV_CHANGE
44 - && evt != NETDEV_REGISTER && evt != NETDEV_UNREGISTER
45 - && evt != NETDEV_CHANGENAME)
46 + && evt != NETDEV_REGISTER && evt != NETDEV_UNREGISTER)
47 return NOTIFY_DONE;
48
49 - if (strcmp(dev->name, trigger_data->device_name))
50 + if (!(dev == trigger_data->net_dev ||
51 + (evt == NETDEV_REGISTER && !strcmp(dev->name, trigger_data->device_name))))
52 return NOTIFY_DONE;
53
54 cancel_delayed_work_sync(&trigger_data->work);
55 @@ -320,12 +320,9 @@ static int netdev_trig_notify(struct not
56 dev_hold(dev);
57 trigger_data->net_dev = dev;
58 break;
59 - case NETDEV_CHANGENAME:
60 case NETDEV_UNREGISTER:
61 - if (trigger_data->net_dev) {
62 - dev_put(trigger_data->net_dev);
63 - trigger_data->net_dev = NULL;
64 - }
65 + dev_put(trigger_data->net_dev);
66 + trigger_data->net_dev = NULL;
67 break;
68 case NETDEV_UP:
69 case NETDEV_CHANGE: