[PATCH v1] power: supply: ltc2941-battery-gauge: fix use-after-free

[PATCH v1] power: supply: ltc2941-battery-gauge: fix use-after-free

[Sven Van Asbroeck]

This driver's remove path calls cancel_delayed_work().
However, that function does not wait until the work function
finishes. This could mean that the work function is still
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
that the work is properly cancelled, no longer running, and
unable to re-schedule itself.

This issue was detected with the help of Coccinelle.

Cc: stable <stable@vger.kernel.org>
Signed-off-by: Sven Van Asbroeck <TheSven73@gmail.com>
---
 drivers/power/supply/ltc2941-battery-gauge.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/power/supply/ltc2941-battery-gauge.c b/drivers/power/supply/ltc2941-battery-gauge.c
index da49436176cd..30a9014b2f95 100644
--- a/drivers/power/supply/ltc2941-battery-gauge.c
+++ b/drivers/power/supply/ltc2941-battery-gauge.c
@@ -449,7 +449,7 @@ static int ltc294x_i2c_remove(struct i2c_client *client)
 {
 	struct ltc294x_info *info = i2c_get_clientdata(client);
 
-	cancel_delayed_work(&info->work);
+	cancel_delayed_work_sync(&info->work);
 	power_supply_unregister(info->supply);
 	return 0;
 }
-- 
2.17.1

Re: [PATCH v1] power: supply: ltc2941-battery-gauge: fix use-after-free

[Sven Van Asbroeck]

On Thu, Sep 19, 2019 at 2:29 PM Sasha Levin <sashal@kernel.org> wrote:
>
> Hi,
>
> [This is an automated email]
>
> This commit has been processed because it contains a -stable tag.
> The stable tag indicates that it's relevant for the following trees: all
>
> The bot has tested the following trees: v5.2.15, v4.19.73, v4.14.144, v4.9.193, v4.4.193.
>
> v5.2.15: Build OK!
> v4.19.73: Build OK!
> v4.14.144: Build OK!
> v4.9.193: Build OK!
> v4.4.193: Failed to apply! Possible dependencies:
>     Unable to calculate
>
>
> NOTE: The patch will not be queued to stable trees until it is upstream.
>
> How should we proceed with this patch?
>
> --
> Thanks,
> Sasha

Doesn't apply on 4.4 because power supply drivers moved to a different
directory (power/supply) between 4.4 and 4.9.

I will post a patch with a fixed-up file path, marked as "[PATCH 4.4 v1]".
If this should be addressed differently, please let me know.

Sven

[PATCH 4.4 v1] power: supply: ltc2941-battery-gauge: fix use-after-free

[Sven Van Asbroeck]

This driver's remove path calls cancel_delayed_work().
However, that function does not wait until the work function
finishes. This could mean that the work function is still
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
that the work is properly cancelled, no longer running, and
unable to re-schedule itself.

This issue was detected with the help of Coccinelle.

Cc: stable <stable@vger.kernel.org>
Signed-off-by: Sven Van Asbroeck <TheSven73@gmail.com>
---
 drivers/power/ltc2941-battery-gauge.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/power/ltc2941-battery-gauge.c b/drivers/power/ltc2941-battery-gauge.c
index da49436176cd..30a9014b2f95 100644
--- a/drivers/power/ltc2941-battery-gauge.c
+++ b/drivers/power/ltc2941-battery-gauge.c
@@ -449,7 +449,7 @@ static int ltc294x_i2c_remove(struct i2c_client *client)
 {
 	struct ltc294x_info *info = i2c_get_clientdata(client);
 
-	cancel_delayed_work(&info->work);
+	cancel_delayed_work_sync(&info->work);
 	power_supply_unregister(info->supply);
 	return 0;
 }
-- 
2.17.1

Re: [PATCH 4.4 v1] power: supply: ltc2941-battery-gauge: fix use-after-free

[Greg KH]

On Thu, Sep 19, 2019 at 03:02:08PM -0400, Sven Van Asbroeck wrote:
> This driver's remove path calls cancel_delayed_work().
> However, that function does not wait until the work function
> finishes. This could mean that the work function is still
> 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
> that the work is properly cancelled, no longer running, and
> unable to re-schedule itself.
> 
> This issue was detected with the help of Coccinelle.
> 
> Cc: stable <stable@vger.kernel.org>
> Signed-off-by: Sven Van Asbroeck <TheSven73@gmail.com>
> ---
>  drivers/power/ltc2941-battery-gauge.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/power/ltc2941-battery-gauge.c b/drivers/power/ltc2941-battery-gauge.c
> index da49436176cd..30a9014b2f95 100644
> --- a/drivers/power/ltc2941-battery-gauge.c
> +++ b/drivers/power/ltc2941-battery-gauge.c
> @@ -449,7 +449,7 @@ static int ltc294x_i2c_remove(struct i2c_client *client)
>  {
>  	struct ltc294x_info *info = i2c_get_clientdata(client);
>  
> -	cancel_delayed_work(&info->work);
> +	cancel_delayed_work_sync(&info->work);
>  	power_supply_unregister(info->supply);
>  	return 0;
>  }
> -- 
> 2.17.1
> 

What is the git commit id of this patch in Linus's tree?

thanks,

greg k-h

Re: [PATCH 4.4 v1] power: supply: ltc2941-battery-gauge: fix use-after-free

[Sven Van Asbroeck]

On Mon, Dec 2, 2019 at 1:43 PM Greg KH <greg@kroah.com> wrote:
>
> What is the git commit id of this patch in Linus's tree?

As far as I know, the mainline version of this patch is still queued up
in Sebastian's 'fixes' branch, and has not made it out to Linus's
tree yet.

https://git.kernel.org/pub/scm/linux/kernel/git/sre/linux-power-supply.git/log/?h=fixes

Re: [PATCH 4.4 v1] power: supply: ltc2941-battery-gauge: fix use-after-free

[Greg KH]

On Mon, Dec 02, 2019 at 02:59:26PM -0500, Sven Van Asbroeck wrote:
> On Mon, Dec 2, 2019 at 1:43 PM Greg KH <greg@kroah.com> wrote:
> >
> > What is the git commit id of this patch in Linus's tree?
> 
> As far as I know, the mainline version of this patch is still queued up
> in Sebastian's 'fixes' branch, and has not made it out to Linus's
> tree yet.
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/sre/linux-power-supply.git/log/?h=fixes

Now queued up, thanks!

greg k-h

Re: [PATCH v1] power: supply: ltc2941-battery-gauge: fix use-after-free

[Sebastian Reichel]

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Hi,

On Thu, Sep 19, 2019 at 11:11:37AM -0400, Sven Van Asbroeck wrote:
> This driver's remove path calls cancel_delayed_work().
> However, that function does not wait until the work function
> finishes. This could mean that the work function is still
> 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
> that the work is properly cancelled, no longer running, and
> unable to re-schedule itself.
> 
> This issue was detected with the help of Coccinelle.
> 
> Cc: stable <stable@vger.kernel.org>
> Signed-off-by: Sven Van Asbroeck <TheSven73@gmail.com>
> ---

Thanks, queued.

-- Sebastian

>  drivers/power/supply/ltc2941-battery-gauge.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/power/supply/ltc2941-battery-gauge.c b/drivers/power/supply/ltc2941-battery-gauge.c
> index da49436176cd..30a9014b2f95 100644
> --- a/drivers/power/supply/ltc2941-battery-gauge.c
> +++ b/drivers/power/supply/ltc2941-battery-gauge.c
> @@ -449,7 +449,7 @@ static int ltc294x_i2c_remove(struct i2c_client *client)
>  {
>  	struct ltc294x_info *info = i2c_get_clientdata(client);
>  
> -	cancel_delayed_work(&info->work);
> +	cancel_delayed_work_sync(&info->work);
>  	power_supply_unregister(info->supply);
>  	return 0;
>  }
> -- 
> 2.17.1
> 

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