[PATCH] ASoC: Intel: Skylake: fix possible memory leak in skl_codec_device_init()

[Cezary Rojewski]

On 2022-10-20 5:45 AM, Yang Yingliang wrote:
> If snd_hdac_device_register() fails, 'codec' is leaked, free it
> in snd_hdac_device_exit(). And device_initialize() is called in
> snd_hdac_device_init(), it should call put_device() to give up
> reference or the name allocated in dev_set_name() is leaked.
> The snd_hdac_device_exit() will be called in dev->release().
> 
> Fixes: e4746d94d00c ("ASoC: Intel: Skylake: Introduce HDA codec init and exit routines")
> Signed-off-by: Yang Yingliang <yangyingliang at huawei.com>
> ---
>   sound/soc/intel/skylake/skl.c | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/sound/soc/intel/skylake/skl.c b/sound/soc/intel/skylake/skl.c
> index bbba2df33aaf..f0048e3fa619 100644
> --- a/sound/soc/intel/skylake/skl.c
> +++ b/sound/soc/intel/skylake/skl.c
> @@ -691,7 +691,11 @@ static void load_codec_module(struct hda_codec *codec)
>   
>   static void skl_codec_device_exit(struct device *dev)
>   {
> -	snd_hdac_device_exit(dev_to_hdac_dev(dev));
> +	struct hdac_device *hdac_dev = dev_to_hdac_dev(dev);
> +	struct hda_codec *codec = container_of(hdac_dev, struct hda_codec, core);
> +
> +	snd_hdac_device_exit(hdac_dev);
> +	kfree(codec);
>   }
>   
>   static struct hda_codec *skl_codec_device_init(struct hdac_bus *bus, int addr)
> @@ -711,7 +715,7 @@ static struct hda_codec *skl_codec_device_init(struct hdac_bus *bus, int addr)
>   	ret = snd_hdac_device_register(&codec->core);
>   	if (ret) {
>   		dev_err(bus->dev, "failed to register hdac device\n");
> -		snd_hdac_device_exit(&codec->core);
> +		put_device(&codec->core.dev);
>   		return ERR_PTR(ret);
>   	}
>   

Hello,

That's a tricky one. And that's because the code added in commit [1] 
which you're fixing here, basically mimics the original code that has 
been removed later on in the series of mine [2].

The key part is: function snd_hda_codec_device_init() replaced 
snd_hdac_device_init(). I believe the former may generate codec-leak in 
situations you speak of.

Now, on to the fix. My suggestion is to start with removing the 
following line:
	codec->core.dev.release = skl_codec_device_exit;

and skl_codec_device_exit() function itself. Let's leave the default as 
is and see if the leak still occurs.


[1]: 
https://lore.kernel.org/alsa-devel/20220816111727.3218543-2-cezary.rojewski@intel.com/
[2]: 
https://lore.kernel.org/alsa-devel/20220816111727.3218543-6-cezary.rojewski@intel.com/


Regards,
Czarek