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* [PATCH] watchdog: Fix NULL pointer dereference when releasing cdev
@ 2021-06-23  6:26 Curtis Klein
  2021-06-23 11:31 ` Guenter Roeck
  0 siblings, 1 reply; 2+ messages in thread
From: Curtis Klein @ 2021-06-23  6:26 UTC (permalink / raw)
  To: wim, linux; +Cc: linux-watchdog, linux-kernel, Curtis Klein

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>
---
 drivers/watchdog/watchdog_dev.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 3bab324..ffd8f1a 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -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);
 }
-- 
2.7.4


^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: [PATCH] watchdog: Fix NULL pointer dereference when releasing cdev
  2021-06-23  6:26 [PATCH] watchdog: Fix NULL pointer dereference when releasing cdev Curtis Klein
@ 2021-06-23 11:31 ` Guenter Roeck
  0 siblings, 0 replies; 2+ messages in thread
From: Guenter Roeck @ 2021-06-23 11:31 UTC (permalink / raw)
  To: Curtis Klein; +Cc: wim, linux-watchdog, linux-kernel

On Tue, Jun 22, 2021 at 11:26:23PM -0700, Curtis Klein wrote:
> 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>

> ---
>  drivers/watchdog/watchdog_dev.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
> index 3bab324..ffd8f1a 100644
> --- a/drivers/watchdog/watchdog_dev.c
> +++ b/drivers/watchdog/watchdog_dev.c
> @@ -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);
>  }
> -- 
> 2.7.4
> 

^ permalink raw reply	[flat|nested] 2+ messages in thread

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2021-06-23  6:26 [PATCH] watchdog: Fix NULL pointer dereference when releasing cdev Curtis Klein
2021-06-23 11:31 ` Guenter Roeck

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