[PATCH -next] power: supply: generic-adc-battery: fix possible use-after-free in gab_remove()

[PATCH -next] power: supply: generic-adc-battery: fix possible use-after-free in gab_remove()

[Yang Yingliang]

This driver's remove path calls cancel_delayed_work(). However, that
function does not wait until the work function finishes. This means
that the callback function may still be running after the driver's
remove function has finished, which would result in a use-after-free.

Fix by calling cancel_delayed_work_sync(), which ensures that
the work is properly cancelled, no longer running, and unable
to re-schedule itself.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
---
 drivers/power/supply/generic-adc-battery.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/power/supply/generic-adc-battery.c b/drivers/power/supply/generic-adc-battery.c
index 0032069fbc2b..66039c665dd1 100644
--- a/drivers/power/supply/generic-adc-battery.c
+++ b/drivers/power/supply/generic-adc-battery.c
@@ -373,7 +373,7 @@ static int gab_remove(struct platform_device *pdev)
 	}
 
 	kfree(adc_bat->psy_desc.properties);
-	cancel_delayed_work(&adc_bat->bat_work);
+	cancel_delayed_work_sync(&adc_bat->bat_work);
 	return 0;
 }
 
-- 
2.25.1

Re: [PATCH -next] power: supply: generic-adc-battery: fix possible use-after-free in gab_remove()

[Sebastian Reichel]

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Hi,

On Wed, Apr 07, 2021 at 05:17:06PM +0800, Yang Yingliang wrote:
> This driver's remove path calls cancel_delayed_work(). However, that
> function does not wait until the work function finishes. This means
> that the callback function may still be running after the driver's
> remove function has finished, which would result in a use-after-free.
> 
> Fix by calling cancel_delayed_work_sync(), which ensures that
> the work is properly cancelled, no longer running, and unable
> to re-schedule itself.
> 
> Reported-by: Hulk Robot <hulkci@huawei.com>
> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
> ---

Thanks, queued.

-- Sebastian

>  drivers/power/supply/generic-adc-battery.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/power/supply/generic-adc-battery.c b/drivers/power/supply/generic-adc-battery.c
> index 0032069fbc2b..66039c665dd1 100644
> --- a/drivers/power/supply/generic-adc-battery.c
> +++ b/drivers/power/supply/generic-adc-battery.c
> @@ -373,7 +373,7 @@ static int gab_remove(struct platform_device *pdev)
>  	}
>  
>  	kfree(adc_bat->psy_desc.properties);
> -	cancel_delayed_work(&adc_bat->bat_work);
> +	cancel_delayed_work_sync(&adc_bat->bat_work);
>  	return 0;
>  }
>  
> -- 
> 2.25.1
> 

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