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

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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>
v19.07.3_mercusys_ac12_duma
Rafał Miłecki 5 years ago
parent 64bb88841f
commit 9e32e288f0
2 changed files with 138 additions and 0 deletions
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69
target/linux/generic/backport-4.14/401-v5.2-leds-trigger-netdev-fix-refcnt-leak-on-interface-ren.patch
Unescape Escape View File

@ -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:

69
target/linux/generic/backport-4.19/400-v5.2-leds-trigger-netdev-fix-refcnt-leak-on-interface-ren.patch
Unescape Escape View File

@ -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:
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