Skip to content
Permalink
Browse files

kernel: fix refcnt leak in LED netdev trigger on interface rename

This fixes a possible unbalanced dev_hold():
> iw dev bar del
[  237.355366] unregister_netdevice: waiting for bar to become free. Usage count = 1
[  247.435362] unregister_netdevice: waiting for bar to become free. Usage count = 1
[  257.545366] unregister_netdevice: waiting for bar to become free. Usage count = 1

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
  • Loading branch information...
Rafał Miłecki
Rafał Miłecki committed Mar 5, 2019
1 parent 64bb888 commit 9e32e288f0de3fa8c7ae1d193aec608648430759
@@ -0,0 +1,69 @@
From dd7590a3ab3f0804ed5e930295e2caa5979e3958 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
Date: Thu, 28 Feb 2019 22:57:33 +0100
Subject: [PATCH] leds: trigger: netdev: fix refcnt leak on interface rename
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Renaming a netdev-trigger-tracked interface was resulting in an
unbalanced dev_hold().

Example:
> iw phy phy0 interface add foo type __ap
> echo netdev > trigger
> echo foo > device_name
> ip link set foo name bar
> iw dev bar del
[ 237.355366] unregister_netdevice: waiting for bar to become free. Usage count = 1
[ 247.435362] unregister_netdevice: waiting for bar to become free. Usage count = 1
[ 257.545366] unregister_netdevice: waiting for bar to become free. Usage count = 1

Above problem was caused by trigger checking a dev->name which obviously
changes after renaming an interface. It meant missing all further events
including the NETDEV_UNREGISTER which is required for calling dev_put().

This change fixes that by:
1) Comparing device struct *address* for notification-filtering purposes
2) Dropping unneeded NETDEV_CHANGENAME code (no behavior change)

Fixes: 06f502f57d0d ("leds: trigger: Introduce a NETDEV trigger")
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
---
drivers/leds/trigger/ledtrig-netdev.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)

--- a/drivers/leds/trigger/ledtrig-netdev.c
+++ b/drivers/leds/trigger/ledtrig-netdev.c
@@ -299,11 +299,11 @@ static int netdev_trig_notify(struct not
notifier);

if (evt != NETDEV_UP && evt != NETDEV_DOWN && evt != NETDEV_CHANGE
- && evt != NETDEV_REGISTER && evt != NETDEV_UNREGISTER
- && evt != NETDEV_CHANGENAME)
+ && evt != NETDEV_REGISTER && evt != NETDEV_UNREGISTER)
return NOTIFY_DONE;

- if (strcmp(dev->name, trigger_data->device_name))
+ if (!(dev == trigger_data->net_dev ||
+ (evt == NETDEV_REGISTER && !strcmp(dev->name, trigger_data->device_name))))
return NOTIFY_DONE;

cancel_delayed_work_sync(&trigger_data->work);
@@ -318,12 +318,9 @@ static int netdev_trig_notify(struct not
dev_hold(dev);
trigger_data->net_dev = dev;
break;
- case NETDEV_CHANGENAME:
case NETDEV_UNREGISTER:
- if (trigger_data->net_dev) {
- dev_put(trigger_data->net_dev);
- trigger_data->net_dev = NULL;
- }
+ dev_put(trigger_data->net_dev);
+ trigger_data->net_dev = NULL;
break;
case NETDEV_UP:
case NETDEV_CHANGE:
@@ -0,0 +1,69 @@
From dd7590a3ab3f0804ed5e930295e2caa5979e3958 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
Date: Thu, 28 Feb 2019 22:57:33 +0100
Subject: [PATCH] leds: trigger: netdev: fix refcnt leak on interface rename
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Renaming a netdev-trigger-tracked interface was resulting in an
unbalanced dev_hold().

Example:
> iw phy phy0 interface add foo type __ap
> echo netdev > trigger
> echo foo > device_name
> ip link set foo name bar
> iw dev bar del
[ 237.355366] unregister_netdevice: waiting for bar to become free. Usage count = 1
[ 247.435362] unregister_netdevice: waiting for bar to become free. Usage count = 1
[ 257.545366] unregister_netdevice: waiting for bar to become free. Usage count = 1

Above problem was caused by trigger checking a dev->name which obviously
changes after renaming an interface. It meant missing all further events
including the NETDEV_UNREGISTER which is required for calling dev_put().

This change fixes that by:
1) Comparing device struct *address* for notification-filtering purposes
2) Dropping unneeded NETDEV_CHANGENAME code (no behavior change)

Fixes: 06f502f57d0d ("leds: trigger: Introduce a NETDEV trigger")
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
---
drivers/leds/trigger/ledtrig-netdev.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)

--- a/drivers/leds/trigger/ledtrig-netdev.c
+++ b/drivers/leds/trigger/ledtrig-netdev.c
@@ -301,11 +301,11 @@ static int netdev_trig_notify(struct not
container_of(nb, struct led_netdev_data, notifier);

if (evt != NETDEV_UP && evt != NETDEV_DOWN && evt != NETDEV_CHANGE
- && evt != NETDEV_REGISTER && evt != NETDEV_UNREGISTER
- && evt != NETDEV_CHANGENAME)
+ && evt != NETDEV_REGISTER && evt != NETDEV_UNREGISTER)
return NOTIFY_DONE;

- if (strcmp(dev->name, trigger_data->device_name))
+ if (!(dev == trigger_data->net_dev ||
+ (evt == NETDEV_REGISTER && !strcmp(dev->name, trigger_data->device_name))))
return NOTIFY_DONE;

cancel_delayed_work_sync(&trigger_data->work);
@@ -320,12 +320,9 @@ static int netdev_trig_notify(struct not
dev_hold(dev);
trigger_data->net_dev = dev;
break;
- case NETDEV_CHANGENAME:
case NETDEV_UNREGISTER:
- if (trigger_data->net_dev) {
- dev_put(trigger_data->net_dev);
- trigger_data->net_dev = NULL;
- }
+ dev_put(trigger_data->net_dev);
+ trigger_data->net_dev = NULL;
break;
case NETDEV_UP:
case NETDEV_CHANGE:

0 comments on commit 9e32e28

Please sign in to comment.
You can’t perform that action at this time.