Re: [PATCH] gpiolib: free device name on error path to fix kmemleak

[Andy Shevchenko]

On Fri, Jan 29, 2021 at 2:01 PM <quanyang.wang@xxxxxxxxxxxxx> wrote:
>
> From: Quanyang Wang <quanyang.wang@xxxxxxxxxxxxx>
>
> In gpiochip_add_data_with_key, we should check the return value of
> dev_set_name to ensure that device name is allocated successfully
> and then add a label on the error path to free device name to fix
> kmemleak as below:

Thanks for the report.
Unfortunately...

> +       ret = dev_set_name(&gdev->dev, GPIOCHIP_NAME "%d", gdev->id);
> +       if (ret)
> +               goto err_free_ida;

...

> +err_free_dev_name:
> +       kfree(dev_name(&gdev->dev));

...this approach seems to  create a possible double free if I'm not mistaken.

The idea is that device name should be cleaned in kobject ->release()
callback when device is put.

Can you elaborate?

-- 
With Best Regards,
Andy Shevchenko