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

[Yang Yingliang]

Hi,

On 2022/10/20 16:39, Cezary Rojewski wrote:
> 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.
Yes, after using snd_hda_codec_device_init(), 'codec' is leaked.
And there is another leak, the name allocated in dev_set_name() called 
in snd_hdac_device_init() is always leaked if snd_hdac_device_register() 
fails
in snd_hdac_ext_bus_device_init() which is introduced by comit 
dfe66a18780d ("ALSA: hdac_ext: add extended HDA bus").
>
> 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.
OK, I will send a v2.

Thanks,
Yang
>
>
> [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
> .