Re: [PATCH 2/4] ASoC: fsl: asrc: Use dmaengine API instead of chan->device->dev

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found no new issues
in this patch, but noticed 1 related pre-existing issue it does not
introduce:
- [Critical] ASoC: fsl_asrc_dma: ERR_PTR dereference in
  fsl_asrc_dma_hw_params() [1]
--

commit 5ed216d0bcbc0b97f113bf28f5e8a475ae506081
Author: Frank Li <Frank.Li@nxp.com>

ASoC: fsl: asrc: Use dmaengine API instead of chan->device->dev

This commit replaces direct accesses to chan->device->dev with
dmaengine_get_dma_device() and dmaengine_get_provider_device() in the
Freescale ASRC DMA driver.

> diff --git a/sound/soc/fsl/fsl_asrc_dma.c b/sound/soc/fsl/fsl_asrc_dma.c
> index b417de6abebe4..12c3f19a431a8 100644
> --- a/sound/soc/fsl/fsl_asrc_dma.c
> +++ b/sound/soc/fsl/fsl_asrc_dma.c
> @@ -262,7 +262,7 @@ static int fsl_asrc_dma_hw_params(struct snd_soc_component *component,
>  		pair->dma_data.priority = tmp_data->priority;
>  		dma_release_channel(tmp_chan);
>  
> -		of_dma_node = pair->dma_chan[!dir]->device->dev->of_node;
> +		of_dma_node = dmaengine_get_provider_device(pair->dma_chan[!dir])->of_node;
>  		pair->dma_chan[dir] =
>  			__dma_request_channel(&mask, filter, &pair->dma_data,
>  					      of_dma_node);

[Severity: Critical]
This problem wasn't introduced by this patch, but can tmp_chan->private
dereference an error pointer [1] just above this hunk?

asrc->get_dma_channel() returns an ERR_PTR from dma_request_chan() when
front-end DMA channel allocation fails, whereas fsl_asrc_dma_hw_params()
only checks for !tmp_chan before accessing tmp_chan->private:

sound/soc/fsl/fsl_asrc_dma.c:fsl_asrc_dma_hw_params() {
	...
		tmp_chan = asrc->get_dma_channel(pair, dir);
		if (!tmp_chan) {
			dma_release_channel(pair->dma_chan[!dir]);
			pair->dma_chan[!dir] = NULL;
			return -EINVAL;
		}
		tmp_data = tmp_chan->private;
	...
}

Should this check IS_ERR_OR_NULL(tmp_chan) instead?

[1] https://sashiko.dev/#/bug/linux-564b9a37-0988-4e75-909c-eb977f811fd1

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261106-dma_sound_cleanup-v1-0-5eb8a7b81e87@nxp.com?part=2