ASoC: SOF: Don't allow pointer operations on unconfigured streams

When reporting the pointer for a compressed stream we report the current
I/O frame position by dividing the position by the number of channels
multiplied by the number of container bytes. These values default to 0 and
are only configured as part of setting the stream parameters so this allows
a divide by zero to be configured. Validate that they are non zero,
returning an error if not

Fixes: c1a731c ("ASoC: SOF: compress: Add support for computing timestamps")
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260326-asoc-compress-tstamp-params-v1-1-3dc735b3d599@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: broonie

sound/soc/sof/compress.c

@@ -381,6 +381,9 @@ static int sof_compr_pointer(struct snd_soc_component *component,
 	if (!spcm)
 		return -EINVAL;
 
+	if (!sstream->channels || !sstream->sample_container_bytes)
+		return -EBUSY;
+
 	tstamp->sampling_rate = sstream->sampling_rate;
 	tstamp->copied_total = sstream->copied_total;
 	tstamp->pcm_io_frames = div_u64(spcm->stream[cstream->direction].posn.dai_posn,