[alsa-devel] [PATCH] SoC: cht_bsw_rt5645: Fix writing to string literal

[Pierre-Louis Bossart]

On 2/15/16 1:36 PM, Carlo Caione wrote:
> From: Carlo Caione <carlo at endlessm.com>
>
> We cannot use strcpy() to write to a const char * location. This is
> causing a 'BUG: unable to handle kernel paging request' error at boot
> when using the cht-bsw-rt5645 driver.
>
> With this patch we also fix a wrong indexing in the driver where the
> codec_name of the wrong dai_link is being overwritten.
>
> Signed-off-by: Carlo Caione <carlo at endlessm.com>
> ---
>   sound/soc/intel/atom/sst-atom-controls.h | 1 +
>   sound/soc/intel/boards/cht_bsw_rt5645.c  | 4 ++--
>   2 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/sound/soc/intel/atom/sst-atom-controls.h b/sound/soc/intel/atom/sst-atom-controls.h
> index e011311..6f88d1c 100644
> --- a/sound/soc/intel/atom/sst-atom-controls.h
> +++ b/sound/soc/intel/atom/sst-atom-controls.h
> @@ -30,6 +30,7 @@ enum {
>   	MERR_DPCM_AUDIO = 0,
>   	MERR_DPCM_DEEP_BUFFER,
>   	MERR_DPCM_COMPR,
> +	MERR_DPCM_BE,
>   };
>
>   /* define a bit for each mixer input */
> diff --git a/sound/soc/intel/boards/cht_bsw_rt5645.c b/sound/soc/intel/boards/cht_bsw_rt5645.c
> index e6cf800..89b4c032 100644
> --- a/sound/soc/intel/boards/cht_bsw_rt5645.c
> +++ b/sound/soc/intel/boards/cht_bsw_rt5645.c
> @@ -282,7 +282,7 @@ static struct snd_soc_dai_link cht_dailink[] = {
>   	},
>   	/* CODEC<->CODEC link */
>   	/* back ends */
> -	{
> +	[MERR_DPCM_BE] = {
>   		.name = "SSP2-Codec",
>   		.be_id = 1,
>   		.cpu_dai_name = "ssp2-port",
> @@ -357,7 +357,7 @@ static int snd_cht_mc_probe(struct platform_device *pdev)
>   	card->dev = &pdev->dev;
>   	sprintf(codec_name, "i2c-%s:00", drv->acpi_card->codec_id);
>   	/* set correct codec name */
> -	strcpy((char *)card->dai_link[2].codec_name, codec_name);
> +	card->dai_link[MERR_DPCM_BE].codec_name = kstrdup(codec_name, GFP_KERNEL);

It's probably less problematic to find the index in a different way. 
Adding a new definition in the platform driver doesn't seem quite right.