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watchdog: core: fix null pointer dereference when releasing cdev 

watchdog_stop() calls watchdog_update_worker() which needs a valid
wdd->wd_data pointer. So, when unregistering the cdev, clear the
pointers after we call watchdog_stop(), not before.

Fixes: bb292ac1c6 ("watchdog: Introduce watchdog_stop_on_unregister helper")
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
This commit is contained in:
Wolfram Sang 2018-08-28 12:13:47 +02:00 committed by Wim Van Sebroeck
parent 3bed02a296
commit 953b9dd772
1 changed files with 5 additions and 5 deletions
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10
drivers/watchdog/watchdog_dev.c
View File

@ -1019,16 +1019,16 @@ static void watchdog_cdev_unregister(struct watchdog_device *wdd)
old_wd_data = NULL;
}
mutex_lock(&wd_data->lock);
wd_data->wdd = NULL;
wdd->wd_data = NULL;
mutex_unlock(&wd_data->lock);
if (watchdog_active(wdd) &&
test_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status)) {
watchdog_stop(wdd);
}
mutex_lock(&wd_data->lock);
wd_data->wdd = NULL;
wdd->wd_data = NULL;
mutex_unlock(&wd_data->lock);
hrtimer_cancel(&wd_data->timer);
kthread_cancel_work_sync(&wd_data->work);