[PATCH v2 0/1] ASoC: dpcm: acquire dpcm_lock in dpcm_do_trigger()

["Gyeongtaek Lee" <gt82.lee@samsung.com>]

On 03 Dec 2020 07:33:03 +0900, Kuninori Morimoto wrote:
>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@samsung.com>
>> Cc: stable@vger.kernel.org
>> ---
>
>Is this bugfix patch for some recent commit ?
>If so, having Fixes: tag is helpful.
>
>Thank you for your help !!
I tried to find out some change from the history.
However, I saw that dpcm_lock never be held in dpcm_be_dai_trigger() from the beginning.
So, I just fixed some miss from the commit comment and resend.
If you have another suggestion or request, just let me know.

And I have a question.
This patch can’t be applied to stable branches directly by conflict.
I found out following commits are needed to apply this patch into the 5.4 stable.
 ASoC: soc-pcm: remove snd_soc_dpcm_be_get/set_state()
 ASoC: soc-pcm: add snd_soc_dpcm_can_be() and remove duplicate code
In this case, what should I do when stable maintainer requests resolving conflict to me?
Should I send those patches to the maintainer?
Or rewrite the patch on the latest of the each stable?

Thank you!
Gyeongtaek Lee
>
>Best regards
>---
>Kuninori Morimoto
>

Gyeongtaek Lee (1):
  ASoC: dpcm: acquire dpcm_lock in dpcm_do_trigger()

 sound/soc/soc-pcm.c | 62 ++++++++++++++++++++++++++++++++-------------
 1 file changed, 44 insertions(+), 18 deletions(-)


base-commit: fa02fcd94b0c8dff6cc65714510cf25ad194b90d
-- 
2.21.0