[PATCH] ASoC: dpcm: acquire dpcm_lock in dpcm_do_trigger()

[Kuninori Morimoto]

Hi Gyeongtaek

Thank you for your patch

> If stop by underrun and DPCM BE disconnection is run simultaneously,
> data abort can be occurred by the sequence below.
> 
> /* In core X, running dpcm_be_dai_trigger() */
> for_each_dpcm_be(fe, stream, dpcm) {
> /* In core Y, running dpcm_be_disconnect() */
> spin_lock_irqsave(&fe->card->dpcm_lock, flags);
> list_del(&dpcm->list_be);
> list_del(&dpcm->list_fe);
> spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
> kfree(dpcm);
> /* In core X, running dpcm_be_dai_trigger() */
> struct snd_soc_pcm_runtime *be = dpcm->be;   <== Accessing freed memory

It is easy to read/understand if this code has alignment.

> To prevent this situation, dpcm_lock should be acquired during
> iteration of dpcm list in dpcm_do_trigger().
> 
> Signed-off-by: Gyeongtaek Lee <gt82.lee at samsung.com>
> Cc: stable at vger.kernel.org
> ---

Is this bugfix patch for some recent commit ?
If so, having Fixes: tag is helpful.

Thank you for your help !!

Best regards
---
Kuninori Morimoto