[PATCH] ASoC: topology: disable size checks for bytes_ext controls if needed

[PATCH] ASoC: topology: disable size checks for bytes_ext controls if needed

[Kai Vehmanen]

From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>

When CONFIG_SND_CTL_VALIDATION is set, accesses to extended bytes
control generate spurious error messages when the size exceeds 512
bytes, such as

[ 11.224223] sof_sdw sof_sdw: control 2:0:0:EQIIR5.0 eqiir_coef_5:0:
invalid count 1024

In addition the error check returns -EINVAL which has the nasty side
effect of preventing applications accessing controls from working,
e.g.

root@plb:~# alsamixer
cannot load mixer controls: Invalid argument

It's agreed that the control interface has been abused since 2014, but
forcing a check should not prevent existing solutions from working.

This patch skips the checks conditionally if CONFIG_SND_CTL_VALIDATION
is set and the byte array provided by topology is > 512. This
preserves the checks for all other cases.

Fixes: 1a3232d2f61d2 ('ASoC: topology: Add support for TLV bytes controls')
BugLink: https://github.com/thesofproject/linux/issues/2430
Reported-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Jaska Uimonen <jaska.uimonen@intel.com>
Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
---
 sound/soc/soc-topology.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/sound/soc/soc-topology.c b/sound/soc/soc-topology.c
index 28faaf58326e..63086fa8b861 100644
--- a/sound/soc/soc-topology.c
+++ b/sound/soc/soc-topology.c
@@ -592,6 +592,17 @@ static int soc_tplg_kcontrol_bind_io(struct snd_soc_tplg_ctl_hdr *hdr,
 		k->info = snd_soc_bytes_info_ext;
 		k->tlv.c = snd_soc_bytes_tlv_callback;
 
+		/*
+		 * When a topology-based implementation abuses the
+		 * control interface and uses bytes_ext controls of
+		 * more than 512 bytes, we need to disable the size
+		 * checks, otherwise accesses to such controls will
+		 * return an -EINVAL error and prevent the card from
+		 * being configured.
+		 */
+		if (IS_ENABLED(CONFIG_SND_CTL_VALIDATION) && sbe->max > 512)
+			k->access |= SNDRV_CTL_ELEM_ACCESS_SKIP_CHECK;
+
 		ext_ops = tplg->bytes_ext_ops;
 		num_ops = tplg->bytes_ext_ops_count;
 		for (i = 0; i < num_ops; i++) {
-- 
2.27.0

Re: [PATCH] ASoC: topology: disable size checks for bytes_ext controls if needed

[Mark Brown]

On Thu, 17 Sep 2020 13:39:12 +0300, Kai Vehmanen wrote:
> When CONFIG_SND_CTL_VALIDATION is set, accesses to extended bytes
> control generate spurious error messages when the size exceeds 512
> bytes, such as
> 
> [ 11.224223] sof_sdw sof_sdw: control 2:0:0:EQIIR5.0 eqiir_coef_5:0:
> invalid count 1024
> 
> [...]

Applied to

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

Thanks!

[1/1] ASoC: topology: disable size checks for bytes_ext controls if needed
      commit: 6788fc1a66a0c1d1cec7a0f84f94b517eae8611c

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