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

[Carlo Caione]

On Thu, Feb 18, 2016 at 9:02 AM, Pierre-Louis Bossart
<pierre-louis.bossart at linux.intel.com> wrote:
> 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.

MERR_DPCM_BE is intended to be the last dai link index corresponding
to the BE dai. Or at least that was my idea.
What about finding the index using a cycle and stopping on
!strcmp(card->dai_link[i].codec_name, "i2c-10EC5645:00")?

-- 
Carlo Caione  |  +39.340.80.30.096  |  Endless