Re: [PATCH v1] thermal: core: Fix use-after-free in thermal_cooling_device_destroy_sysfs

[Eduardo Valentin]

On Mon, Aug 13, 2018 at 08:14:00PM +0300, Dmitry Osipenko wrote:
> This patch fixes use-after-free that was detected by KASAN. The bug is
> triggered on a CPUFreq driver module unload by freeing 'cdev' on device
> unregister and then using the freed structure during of the cdev's sysfs
> data destruction. The solution is to unregister the sysfs at first, then
> destroy sysfs data and finally release the cooling device.
> 
> Cc: <stable@xxxxxxxxxxxxxxx> # v4.17+
> Fixes: 8ea229511e06 ("thermal: Add cooling device's statistics in sysfs")
> Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>

Acked-by: Eduardo Valentin <edubezval@xxxxxxxxx>

Rui, can you please queue this one?

> ---
>  drivers/thermal/thermal_core.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index 6ab982309e6a..441778100887 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -1102,8 +1102,9 @@ void thermal_cooling_device_unregister(struct thermal_cooling_device *cdev)
>  	mutex_unlock(&thermal_list_lock);
>  
>  	ida_simple_remove(&thermal_cdev_ida, cdev->id);
> -	device_unregister(&cdev->device);
> +	device_del(&cdev->device);
>  	thermal_cooling_device_destroy_sysfs(cdev);
> +	put_device(&cdev->device);
>  }
>  EXPORT_SYMBOL_GPL(thermal_cooling_device_unregister);
>  
> -- 
> 2.18.0
>