[PATCH resent] ASoC: DPCM: Don't pick up BE without substream

[PATCH resent] ASoC: DPCM: Don't pick up BE without substream

[Takashi Iwai]

When DPCM tries to add valid BE connections at dpcm_add_paths(), it
doesn't check whether the picked BE actually supports for the given
stream direction.  Due to that, when an asymmetric BE stream is
present, it picks up wrongly and this may result in a NULL dereference
at a later point where the code assumes the existence of a
corresponding BE substream.

This patch adds the check for the presence of the substream for the
target BE for avoiding the problem above.

Note that we have already some fix for non-existing BE substream at
commit 6246f283d5e0 ("ASoC: dpcm: skip missing substream while
applying symmetry").  But the code path we've hit recently is rather
happening before the previous fix.  So this patch tries to fix at
picking up a BE instead of parsing BE lists.

Fixes: bbf7d3b1c4f4 ("ASoC: soc-pcm: align BE 'atomicity' with that of the FE")
Reported-by: Alex Natalsson <harmoniesworlds@gmail.com>
Cc: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Cc: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Link: https://lore.kernel.org/r/CADs9LoPZH_D+eJ9qjTxSLE5jGyhKsjMN7g2NighZ16biVxsyKw@mail.gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---

Seems that the previous submission was overlooked since I forgot to
put Cc to Mark.  Resubmitted...

 sound/soc/soc-pcm.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
index a827cc3c158a..0c1de5624842 100644
--- a/sound/soc/soc-pcm.c
+++ b/sound/soc/soc-pcm.c
@@ -1318,6 +1318,9 @@ static struct snd_soc_pcm_runtime *dpcm_get_be(struct snd_soc_card *card,
 		if (!be->dai_link->no_pcm)
 			continue;
 
+		if (!snd_soc_dpcm_get_substream(be, stream))
+			continue;
+
 		for_each_rtd_dais(be, i, dai) {
 			w = snd_soc_dai_get_widget(dai, stream);
 
-- 
2.35.3

Re: [PATCH resent] ASoC: DPCM: Don't pick up BE without substream

[Mark Brown]

On Mon, 1 Aug 2022 19:05:10 +0200, Takashi Iwai wrote:
> When DPCM tries to add valid BE connections at dpcm_add_paths(), it
> doesn't check whether the picked BE actually supports for the given
> stream direction.  Due to that, when an asymmetric BE stream is
> present, it picks up wrongly and this may result in a NULL dereference
> at a later point where the code assumes the existence of a
> corresponding BE substream.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next

Thanks!

[1/1] ASoC: DPCM: Don't pick up BE without substream
      commit: 754590651ccbbcc74a7c20907be4bb15d642bde3

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark