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watchdog: Fix NULL pointer dereference when releasing cdev

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watchdog_hrtimer_pretimeout_stop needs the watchdog device to have a
valid pointer to the watchdog core data to stop the pretimeout hrtimer.
Therefore it needs to be called before the pointers are cleared in
watchdog_cdev_unregister.

Fixes: 7b7d2fdc8c3e ("watchdog: Add hrtimer-based pretimeout feature")
Reported-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Curtis Klein <curtis.klein@hpe.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/1624429583-5720-1-git-send-email-curtis.klein@hpe.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
This commit is contained in:
Curtis Klein 2021-06-22 23:26:23 -07:00 committed by Wim Van Sebroeck
parent cf6ea95423
commit c7b178dae1
1 changed files with 2 additions and 1 deletions
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3
drivers/watchdog/watchdog_dev.c
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@ -1096,6 +1096,8 @@ static void watchdog_cdev_unregister(struct watchdog_device *wdd)
watchdog_stop(wdd);
}
watchdog_hrtimer_pretimeout_stop(wdd);
mutex_lock(&wd_data->lock);
wd_data->wdd = NULL;
wdd->wd_data = NULL;
@ -1103,7 +1105,6 @@ static void watchdog_cdev_unregister(struct watchdog_device *wdd)
hrtimer_cancel(&wd_data->timer);
kthread_cancel_work_sync(&wd_data->work);
watchdog_hrtimer_pretimeout_stop(wdd);
put_device(&wd_data->dev);
}