Re: [PATCH 1/2] ASoC: SOF: sof-client-probes: fix error codes in sof_probes_compr_copy()

["Péter Ujfalusi" <peter.ujfalusi@linux.intel.com>]

On 06/07/2022 10:23, Dan Carpenter wrote:
> This function tries to return the number of bytes that it was able to
> copy to the user.  However, because there are multiple calls to
> copy_to_user() in a row that means the bytes are not necessarily
> consecutive so it's not useful.  Just return -EFAULT instead.

The function is copying data from a circular buffer to a use buffer.
The single copy_to_user() is used when we don't have wrapping, the
'double' copy_to_user() is when we wrap, so first copy is from the end
of the buffer then we copy the data from the start of the buffer to get
all data.

> Fixes: 3dc0d7091778 ("ASoC: SOF: Convert the generic probe support to SOF client")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
>  sound/soc/sof/sof-client-probes.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/sound/soc/sof/sof-client-probes.c b/sound/soc/sof/sof-client-probes.c
> index 1f1ea93a7fbf..679bc7d371fc 100644
> --- a/sound/soc/sof/sof-client-probes.c
> +++ b/sound/soc/sof/sof-client-probes.c
> @@ -385,7 +385,6 @@ static int sof_probes_compr_copy(struct snd_soc_component *component,
>  	struct snd_compr_runtime *rtd = cstream->runtime;
>  	unsigned int offset, n;
>  	void *ptr;
> -	int ret;
>  
>  	if (count > rtd->buffer_size)
>  		count = rtd->buffer_size;
> @@ -395,14 +394,15 @@ static int sof_probes_compr_copy(struct snd_soc_component *component,
>  	n = rtd->buffer_size - offset;
>  
>  	if (count < n) {
> -		ret = copy_to_user(buf, ptr, count);
> +		if (copy_to_user(buf, ptr, count))
> +			return -EFAULT;
>  	} else {
> -		ret = copy_to_user(buf, ptr, n);
> -		ret += copy_to_user(buf + n, rtd->dma_area, count - n);
> +		if (copy_to_user(buf, ptr, n))
> +			return -EFAULT;
> +		if (copy_to_user(buf + n, rtd->dma_area, count - n))
> +			return -EFAULT;
>  	}
>  
> -	if (ret)
> -		return count - ret;
>  	return count;
>  }
>  

-- 
Péter