ASoC: SOF: topology: Prevent NULL pointer dereference with no TLV

When there is no TLV data in topology, extracting the TLV data
could result in a NULL pointer exception. Prevent this by making
sure that the TLV data exists before extracting it.
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Reviewed-by: Paul Olaru <paul.olaru@oss.nxp.com>
Reviewed-by: Bard Liao <bard.liao@intel.com>
Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Link: https://lore.kernel.org/r/20210201093128.1226603-1-kai.vehmanen@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/topology.c

@@ -1073,7 +1073,7 @@ static int sof_control_load_volume(struct snd_soc_component *scomp,
 	scontrol->cmd = SOF_CTRL_CMD_VOLUME;
 
 	/* extract tlv data */
-	if (get_tlv_data(kc->tlv.p, tlv) < 0) {
+	if (!kc->tlv.p || get_tlv_data(kc->tlv.p, tlv) < 0) {
 		dev_err(scomp->dev, "error: invalid TLV data\n");
 		ret = -EINVAL;
 		goto out_free;