[PATCH v5 0/1] ASoC: dpcm: acquire dpcm_lock in dpcm_do_trigger()

[Gyeongtaek Lee]

On Wed, 2021-02-17 16:29, Takashi Iwai wrote:
>On Wed, 17 Feb 2021 05:31:49 +0100,
>Gyeongtaek Lee wrote:
>> 
>> If stop by underrun and DPCM BE disconnection is run simultaneously,
>> data abort can be occurred by the sequence below.
>> 
>> CPU0					CPU1
>> dpcm_be_dai_trigger():			dpcm_be_disconnect():
>> 
>> for_each_dpcm_be(fe, stream, dpcm) {
>> 
>> 					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);
>> 
>> struct snd_soc_pcm_runtime *be = dpcm->be; <-- Accessing freed memory
>> 
>> To prevent this situation, dpcm_lock should be acquired during
>> iteration of dpcm list in dpcm_be_dai_trigger().
>
>I don't think we can apply spin lock there blindly.  There is
>non-atomic PCM that must not take a spin lock there, too.
Hi, Takashi

I fixed the patch to hold dpcm_lock during accessing dpcm related data only,
not on the trigger callback of driver.

Thank you.
Gyeongtaek Lee
>
>
>thanks,
>
>Takashi
>

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

 include/sound/soc-dpcm.h |  5 ++++
 sound/soc/soc-pcm.c      | 59 +++++++++++++++++++++++++++++++++-------
 2 files changed, 54 insertions(+), 10 deletions(-)


base-commit: fe07bfda2fb9cdef8a4d4008a409bb02f35f1bd8
-- 
2.21.0