* [PATCH] watchdog: Fix an invalid memory access in 'watchdog_cdev_unregister()'
@ 2021-07-29 16:16 Christophe JAILLET
2021-07-29 16:27 ` Guenter Roeck
0 siblings, 1 reply; 2+ messages in thread
From: Christophe JAILLET @ 2021-07-29 16:16 UTC (permalink / raw)
To: wim, linux, curtis.klein
Cc: linux-watchdog, linux-kernel, kernel-janitors, Christophe JAILLET
A few lines before 'watchdog_hrtimer_pretimeout_stop(wdd)', we explicitly
set 'wdd->wd_data' to NULL.
So, it is more than likely than this call will lead to an invalid
memory access.
Move this call before the 'wdd->wd_data = NULL;'
Fixes: 7b7d2fdc8c3e ("watchdog: Add hrtimer-based pretimeout feature")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
Completely untested!
Not sure at all, that it is the way to fix it.
---
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 3bab32485273..ffd8f1a82355 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);
}
--
2.30.2
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] watchdog: Fix an invalid memory access in 'watchdog_cdev_unregister()'
2021-07-29 16:16 [PATCH] watchdog: Fix an invalid memory access in 'watchdog_cdev_unregister()' Christophe JAILLET
@ 2021-07-29 16:27 ` Guenter Roeck
0 siblings, 0 replies; 2+ messages in thread
From: Guenter Roeck @ 2021-07-29 16:27 UTC (permalink / raw)
To: Christophe JAILLET, wim, curtis.klein
Cc: linux-watchdog, linux-kernel, kernel-janitors
On 7/29/21 9:16 AM, Christophe JAILLET wrote:
> A few lines before 'watchdog_hrtimer_pretimeout_stop(wdd)', we explicitly
> set 'wdd->wd_data' to NULL.
> So, it is more than likely than this call will lead to an invalid
> memory access.
>
> Move this call before the 'wdd->wd_data = NULL;'
>
> Fixes: 7b7d2fdc8c3e ("watchdog: Add hrtimer-based pretimeout feature")
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> ---
> Completely untested!
> Not sure at all, that it is the way to fix it.
Nice catch. Should be ok.
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 3bab32485273..ffd8f1a82355 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);
> }
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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2021-07-29 16:16 [PATCH] watchdog: Fix an invalid memory access in 'watchdog_cdev_unregister()' Christophe JAILLET
2021-07-29 16:27 ` Guenter Roeck
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