Re: [PATCH] ALSA: hda: fix NULL pointer dereference during suspend

[Takashi Iwai <tiwai@suse.de>]

On Wed, 29 Jul 2020 01:10:11 +0200,
Ranjani Sridharan wrote:
> 
> When the ASoC card registration fails and the codec component driver
> never probes, the codec device is not initialized and therefore
> memory for codec->wcaps is not allocated. This results in a NULL pointer
> dereference when the codec driver suspend callback is invoked during
> system suspend. Fix this by returning without performing any actions
> during codec suspend/resume if the card was not registered successfully.
> 
> Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
> Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>

The code changes look OK to apply, but I still wonder how the runtime
PM gets invoked even if the device is not instantiated properly?


thanks,

Takashi

> ---
>  sound/pci/hda/hda_codec.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
> index 3576e2d8452f..9b1f387d18e5 100644
> --- a/sound/pci/hda/hda_codec.c
> +++ b/sound/pci/hda/hda_codec.c
> @@ -2936,6 +2936,10 @@ static int hda_codec_runtime_suspend(struct device *dev)
>  	struct hda_codec *codec = dev_to_hda_codec(dev);
>  	unsigned int state;
>  
> +	/* Nothing to do if card registration fails and the component driver never probes */
> +	if (!codec->card)
> +		return 0;
> +
>  	cancel_delayed_work_sync(&codec->jackpoll_work);
>  	state = hda_call_codec_suspend(codec);
>  	if (codec->link_down_at_suspend ||
> @@ -2950,6 +2954,10 @@ static int hda_codec_runtime_resume(struct device *dev)
>  {
>  	struct hda_codec *codec = dev_to_hda_codec(dev);
>  
> +	/* Nothing to do if card registration fails and the component driver never probes */
> +	if (!codec->card)
> +		return 0;
> +
>  	codec_display_power(codec, true);
>  	snd_hdac_codec_link_up(&codec->core);
>  	hda_call_codec_resume(codec);
> -- 
> 2.25.1
>