Hi Rickard,
On 20.05.2014 21:12, Rickard Strandqvist wrote:
> Hi Tomasz
>
> What I based my patch on is really because of this line:
> if (substream)
> snd_pcm_period_elapsed(substream);
>
> Boojin Kim thought that this was needed, if this is true anymore..? I
> have not been able to immerse myself so much in all patches.
> I'm working on about 100 similar patches.
To me having NULL as either data argument of buffer done callback or
private_data would be a serious driver bug and IMHO it's better to let
it crash with a NULL pointer dereference to let someone notice than mask
it by adding a condition.
Still, I'm not too experienced with ALSA and ASoC, so I might be wrong.
Mark, what do you think about this?
Best regards,
Tomasz
>
> 344b4c48 sound/soc/samsung/dma.c (Boojin Kim 2011-09-02
> 09:44:43 +0900 123) prtd->dma_pos += prtd->dma_period;
> 344b4c48 sound/soc/samsung/dma.c (Boojin Kim 2011-09-02
> 09:44:43 +0900 124) if (prtd->dma_pos >= prtd->dma_end)
> 344b4c48 sound/soc/samsung/dma.c (Boojin Kim 2011-09-02
> 09:44:43 +0900 125) prtd->dma_pos =
> prtd->dma_start;
> 5111c075 sound/soc/s3c24xx/s3c24xx-pcm.c (Mark Brown 2008-04-30
> 17:19:32 +0200 126)
> 344b4c48 sound/soc/samsung/dma.c (Boojin Kim 2011-09-02
> 09:44:43 +0900 127) if (substream)
> 344b4c48 sound/soc/samsung/dma.c (Boojin Kim 2011-09-02
> 09:44:43 +0900 128)
> snd_pcm_period_elapsed(substream);
> c0f41bb1 sound/soc/s3c24xx/s3c24xx-pcm.c (Ben Dooks 2007-02-14
> 13:20:03 +0100 129)
> 344b4c48 sound/soc/samsung/dma.c (Boojin Kim 2011-09-02
> 09:44:43 +0900 130) spin_lock(&prtd->lock);
>
>
> Best regards
> Rickard Strandqvist
>
>
> 2014-05-19 12:52 GMT+02:00 Tomasz Figa <tomasz.figa@xxxxxxxxx>:
>> Hi Rickard,
>>
>> On 15.05.2014 23:57, Rickard Strandqvist wrote:
>>> There is otherwise a risk of a possible null pointer dereference.
>>>
>>> Was largely found by using a static code analysis program called cppcheck.
>>>
>>> Signed-off-by: Rickard Strandqvist <rickard_strandqvist@xxxxxxxxxxxxxxxxxx>
>>> ---
>>> sound/soc/samsung/dma.c | 10 ++++++----
>>> 1 fil ändrad, 6 tillägg(+), 4 borttagningar(-)
>>>
>>> diff --git a/sound/soc/samsung/dma.c b/sound/soc/samsung/dma.c
>>> index dc09b71..b1f6757 100644
>>> --- a/sound/soc/samsung/dma.c
>>> +++ b/sound/soc/samsung/dma.c
>>> @@ -115,17 +115,19 @@ static void dma_enqueue(struct snd_pcm_substream *substream)
>>> static void audio_buffdone(void *data)
>>> {
>>> struct snd_pcm_substream *substream = data;
>>> - struct runtime_data *prtd = substream->runtime->private_data;
>>> + struct runtime_data *prtd = NULL;
>>>
>>> pr_debug("Entered %s\n", __func__);
>>>
>>> - if (prtd->state & ST_RUNNING) {
>>> + if(substream)
>>> + prtd = substream->runtime->private_data;
>>> +
>>> + if (prtd && prtd->state & ST_RUNNING) {
>>> prtd->dma_pos += prtd->dma_period;
>>> if (prtd->dma_pos >= prtd->dma_end)
>>> prtd->dma_pos = prtd->dma_start;
>>>
>>> - if (substream)
>>> - snd_pcm_period_elapsed(substream);
>>> + snd_pcm_period_elapsed(substream);
>>>
>>> spin_lock(&prtd->lock);
>>> if (!samsung_dma_has_circular()) {
>>>
>>
>> Can you find a path (or use case, if possible) on which any of affected
>> pointers will be NULL?
>>
>> Best regards,
>> Tomasz
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