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.
thanks,
Takashi
>
> Signed-off-by: Gyeongtaek Lee <gt82.lee@xxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> sound/soc/soc-pcm.c | 62 ++++++++++++++++++++++++++++++++-------------
> 1 file changed, 44 insertions(+), 18 deletions(-)
>
> diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
> index ee51dc7fd893..718f6b3a309a 100644
> --- a/sound/soc/soc-pcm.c
> +++ b/sound/soc/soc-pcm.c
> @@ -2074,12 +2074,17 @@ static int dpcm_fe_dai_hw_params(struct snd_pcm_substream *substream,
> return ret;
> }
>
> +static int dpcm_can_be_free_stop(struct snd_soc_pcm_runtime *fe,
> + struct snd_soc_pcm_runtime *be, int stream);
> +
> int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
> int cmd)
> {
> struct snd_soc_dpcm *dpcm;
> + unsigned long flags;
> int ret = 0;
>
> + spin_lock_irqsave(&fe->card->dpcm_lock, flags);
> for_each_dpcm_be(fe, stream, dpcm) {
>
> struct snd_soc_pcm_runtime *be = dpcm->be;
> @@ -2102,7 +2107,7 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
>
> ret = soc_pcm_trigger(be_substream, cmd);
> if (ret)
> - return ret;
> + break;
>
> be->dpcm[stream].state = SND_SOC_DPCM_STATE_START;
> break;
> @@ -2112,7 +2117,7 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
>
> ret = soc_pcm_trigger(be_substream, cmd);
> if (ret)
> - return ret;
> + break;
>
> be->dpcm[stream].state = SND_SOC_DPCM_STATE_START;
> break;
> @@ -2122,7 +2127,7 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
>
> ret = soc_pcm_trigger(be_substream, cmd);
> if (ret)
> - return ret;
> + break;
>
> be->dpcm[stream].state = SND_SOC_DPCM_STATE_START;
> break;
> @@ -2131,12 +2136,12 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
> (be->dpcm[stream].state != SND_SOC_DPCM_STATE_PAUSED))
> continue;
>
> - if (!snd_soc_dpcm_can_be_free_stop(fe, be, stream))
> + if (!dpcm_can_be_free_stop(fe, be, stream))
> continue;
>
> ret = soc_pcm_trigger(be_substream, cmd);
> if (ret)
> - return ret;
> + break;
>
> be->dpcm[stream].state = SND_SOC_DPCM_STATE_STOP;
> break;
> @@ -2144,12 +2149,12 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
> if (be->dpcm[stream].state != SND_SOC_DPCM_STATE_START)
> continue;
>
> - if (!snd_soc_dpcm_can_be_free_stop(fe, be, stream))
> + if (!dpcm_can_be_free_stop(fe, be, stream))
> continue;
>
> ret = soc_pcm_trigger(be_substream, cmd);
> if (ret)
> - return ret;
> + break;
>
> be->dpcm[stream].state = SND_SOC_DPCM_STATE_SUSPEND;
> break;
> @@ -2157,17 +2162,20 @@ int dpcm_be_dai_trigger(struct snd_soc_pcm_runtime *fe, int stream,
> if (be->dpcm[stream].state != SND_SOC_DPCM_STATE_START)
> continue;
>
> - if (!snd_soc_dpcm_can_be_free_stop(fe, be, stream))
> + if (!dpcm_can_be_free_stop(fe, be, stream))
> continue;
>
> ret = soc_pcm_trigger(be_substream, cmd);
> if (ret)
> - return ret;
> + break;
>
> be->dpcm[stream].state = SND_SOC_DPCM_STATE_PAUSED;
> break;
> }
> + if (ret)
> + break;
> }
> + spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
>
> return ret;
> }
> @@ -2905,10 +2913,9 @@ static int snd_soc_dpcm_check_state(struct snd_soc_pcm_runtime *fe,
> struct snd_soc_dpcm *dpcm;
> int state;
> int ret = 1;
> - unsigned long flags;
> int i;
>
> - spin_lock_irqsave(&fe->card->dpcm_lock, flags);
> + lockdep_assert_held(&fe->card->dpcm_lock);
> for_each_dpcm_fe(be, stream, dpcm) {
>
> if (dpcm->fe == fe)
> @@ -2922,17 +2929,12 @@ static int snd_soc_dpcm_check_state(struct snd_soc_pcm_runtime *fe,
> }
> }
> }
> - spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
>
> /* it's safe to do this BE DAI */
> return ret;
> }
>
> -/*
> - * We can only hw_free, stop, pause or suspend a BE DAI if any of it's FE
> - * are not running, paused or suspended for the specified stream direction.
> - */
> -int snd_soc_dpcm_can_be_free_stop(struct snd_soc_pcm_runtime *fe,
> +static int dpcm_can_be_free_stop(struct snd_soc_pcm_runtime *fe,
> struct snd_soc_pcm_runtime *be, int stream)
> {
> const enum snd_soc_dpcm_state state[] = {
> @@ -2943,6 +2945,23 @@ int snd_soc_dpcm_can_be_free_stop(struct snd_soc_pcm_runtime *fe,
>
> return snd_soc_dpcm_check_state(fe, be, stream, state, ARRAY_SIZE(state));
> }
> +
> +/*
> + * We can only hw_free, stop, pause or suspend a BE DAI if any of it's FE
> + * are not running, paused or suspended for the specified stream direction.
> + */
> +int snd_soc_dpcm_can_be_free_stop(struct snd_soc_pcm_runtime *fe,
> + struct snd_soc_pcm_runtime *be, int stream)
> +{
> + unsigned long flags;
> + int ret;
> +
> + spin_lock_irqsave(&fe->card->dpcm_lock, flags);
> + ret = dpcm_can_be_free_stop(fe, be, stream);
> + spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
> +
> + return ret;
> +}
> EXPORT_SYMBOL_GPL(snd_soc_dpcm_can_be_free_stop);
>
> /*
> @@ -2952,6 +2971,9 @@ EXPORT_SYMBOL_GPL(snd_soc_dpcm_can_be_free_stop);
> int snd_soc_dpcm_can_be_params(struct snd_soc_pcm_runtime *fe,
> struct snd_soc_pcm_runtime *be, int stream)
> {
> + unsigned long flags;
> + int ret;
> +
> const enum snd_soc_dpcm_state state[] = {
> SND_SOC_DPCM_STATE_START,
> SND_SOC_DPCM_STATE_PAUSED,
> @@ -2959,6 +2981,10 @@ int snd_soc_dpcm_can_be_params(struct snd_soc_pcm_runtime *fe,
> SND_SOC_DPCM_STATE_PREPARE,
> };
>
> - return snd_soc_dpcm_check_state(fe, be, stream, state, ARRAY_SIZE(state));
> + spin_lock_irqsave(&fe->card->dpcm_lock, flags);
> + ret = snd_soc_dpcm_check_state(fe, be, stream, state, ARRAY_SIZE(state));
> + spin_unlock_irqrestore(&fe->card->dpcm_lock, flags);
> +
> + return ret;
> }
> EXPORT_SYMBOL_GPL(snd_soc_dpcm_can_be_params);
> --
> 2.21.0
>
>
>
