[PATCH] ALSA: hda: fix possible memory leak in azx_codec_configure()

[Takashi Iwai]

On Mon, 24 Oct 2022 14:26:46 +0200,
Yang Yingliang wrote:
> 
> If the codec device is registered, after calling snd_hdac_device_unregister(),
> codec has already been removed from chip bus, it should call put_device() to
> give up reference to free codec and device name.
> 
> Fixes: c0f1886de7e1 ("ALSA: hda: intel: Allow repeatedly probing on codec configuration errors")
> Signed-off-by: Yang Yingliang <yangyingliang at huawei.com>

Hrm, are you sure that this will result in a memory leak?
put_device() is called at snd_hda_codec_unregister() that is invoked
via dev_free callback of the snd_hda_codec object -- which is called
when the top-level driver is removed.  I'm afraid that your patch will
lead to a double-free.


thanks,

Takashi

> ---
>  sound/pci/hda/hda_controller.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/sound/pci/hda/hda_controller.c b/sound/pci/hda/hda_controller.c
> index 0ff286b7b66b..f6a73ce300a4 100644
> --- a/sound/pci/hda/hda_controller.c
> +++ b/sound/pci/hda/hda_controller.c
> @@ -1257,8 +1257,11 @@ int azx_codec_configure(struct azx *chip)
>  		/* unregister failed codecs if any codec has been probed */
>  		list_for_each_codec_safe(codec, next, &chip->bus) {
>  			if (!codec->configured) {
> +				bool is_registered = device_is_registered(&codec->core.dev);
>  				codec_err(codec, "Unable to configure, disabling\n");
>  				snd_hdac_device_unregister(&codec->core);
> +				if (is_registered)
> +					put_device(&codec->core.dev);
>  			}
>  		}
>  	}
> -- 
> 2.25.1
>