[PATCH -next] power: supply: s3c_adc_battery: fix possible use-after-free in s3c_adc_bat_remove()

[PATCH -next] power: supply: s3c_adc_battery: fix possible use-after-free in s3c_adc_bat_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/s3c_adc_battery.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/power/supply/s3c_adc_battery.c b/drivers/power/supply/s3c_adc_battery.c
index dc700066d7bc..68d31a3bee48 100644
--- a/drivers/power/supply/s3c_adc_battery.c
+++ b/drivers/power/supply/s3c_adc_battery.c
@@ -390,7 +390,7 @@ static int s3c_adc_bat_remove(struct platform_device *pdev)
 	if (main_bat.charge_finished)
 		free_irq(gpiod_to_irq(main_bat.charge_finished), NULL);
 
-	cancel_delayed_work(&bat_work);
+	cancel_delayed_work_sync(&bat_work);
 
 	if (pdata->exit)
 		pdata->exit();
-- 
2.25.1

Re: [PATCH -next] power: supply: s3c_adc_battery: fix possible use-after-free in s3c_adc_bat_remove()

[Krzysztof Kozlowski]

On 07/04/2021 11:19, 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>
> ---
>  drivers/power/supply/s3c_adc_battery.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>

Best regards,
Krzysztof

Re: [PATCH -next] power: supply: s3c_adc_battery: fix possible use-after-free in s3c_adc_bat_remove()

[Sebastian Reichel]

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Hi,

On Wed, Apr 07, 2021 at 01:15:11PM +0200, Krzysztof Kozlowski wrote:
> On 07/04/2021 11:19, 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>
> > ---
> >  drivers/power/supply/s3c_adc_battery.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> 
> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>

Thanks,

queued.

-- Sebastian

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