2019-11-30 13:12:05

by Wen Yang

Subject: [PATCH] platform/chrome: wilco_ec: fix use after free issue

This is caused by dereferencing 'dev_data' after put_device() in
the telem_device_remove() function.
This patch just moves the put_device() down a bit to avoid this
issue.

Fixes: 1210d1e6bad1 ("platform/chrome: wilco_ec: Add telemetry char device interface")
Signed-off-by: Wen Yang <[email protected]>
Cc: Benson Leung <[email protected]>
Cc: Enric Balletbo i Serra <[email protected]>
Cc: Nick Crews <[email protected]>
Cc: [email protected]
---
drivers/platform/chrome/wilco_ec/telemetry.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/platform/chrome/wilco_ec/telemetry.c b/drivers/platform/chrome/wilco_ec/telemetry.c
index b9d03c3..1176d54 100644
--- a/drivers/platform/chrome/wilco_ec/telemetry.c
+++ b/drivers/platform/chrome/wilco_ec/telemetry.c
@@ -406,8 +406,8 @@ static int telem_device_remove(struct platform_device *pdev)
struct telem_device_data *dev_data = platform_get_drvdata(pdev);

cdev_device_del(&dev_data->cdev, &dev_data->dev);
- put_device(&dev_data->dev);
ida_simple_remove(&telem_ida, MINOR(dev_data->dev.devt));
+ put_device(&dev_data->dev);

return 0;
}
--
1.8.3.1

2019-12-02 11:18:40

by Enric Balletbo i Serra

Subject: Re: [PATCH] platform/chrome: wilco_ec: fix use after free issue

Hi Wen,

On 30/11/19 14:08, Wen Yang wrote:
> This is caused by dereferencing 'dev_data' after put_device() in
> the telem_device_remove() function.
> This patch just moves the put_device() down a bit to avoid this
> issue.
>
> Fixes: 1210d1e6bad1 ("platform/chrome: wilco_ec: Add telemetry char device interface")
> Signed-off-by: Wen Yang <[email protected]>
> Cc: Benson Leung <[email protected]>
> Cc: Enric Balletbo i Serra <[email protected]>
> Cc: Nick Crews <[email protected]>
> Cc: [email protected]
> ---

Queued for 5.5 as is a fix.

Thanks.
Enric

> drivers/platform/chrome/wilco_ec/telemetry.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/platform/chrome/wilco_ec/telemetry.c b/drivers/platform/chrome/wilco_ec/telemetry.c
> index b9d03c3..1176d54 100644
> --- a/drivers/platform/chrome/wilco_ec/telemetry.c
> +++ b/drivers/platform/chrome/wilco_ec/telemetry.c
> @@ -406,8 +406,8 @@ static int telem_device_remove(struct platform_device *pdev)
> struct telem_device_data *dev_data = platform_get_drvdata(pdev);
>
> cdev_device_del(&dev_data->cdev, &dev_data->dev);
> - put_device(&dev_data->dev);
> ida_simple_remove(&telem_ida, MINOR(dev_data->dev.devt));
> + put_device(&dev_data->dev);
>
> return 0;
> }
>