[PATCH 4/6] ASoC: Intel: sof_sdw: avoid crash if invalid DSP topology loaded

[Pierre-Louis Bossart]

From: Kai Vehmanen <kai.vehmanen at linux.intel.com>

The mc_private->hdmi_pcm_list is populated by elements loaded during
DSP topology load. Valid topologies for this machine driver will always
have PCM nodes for HDMI, but driver should fail gracefully even in the case
this is not true. Add a sanity check to sof_sdw_hdmi_card_late_probe()
for this case. Without the fix, a null pcm handle gets dereferenced.

Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski at linux.intel.com>
Reviewed-by: Rander Wang <rander.wang at linux.intel.com>
Signed-off-by: Kai Vehmanen <kai.vehmanen at linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
---
 sound/soc/intel/boards/sof_sdw_hdmi.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/sound/soc/intel/boards/sof_sdw_hdmi.c b/sound/soc/intel/boards/sof_sdw_hdmi.c
index 72316d34eed6..99b04bb2f3a0 100644
--- a/sound/soc/intel/boards/sof_sdw_hdmi.c
+++ b/sound/soc/intel/boards/sof_sdw_hdmi.c
@@ -55,6 +55,9 @@ int sof_sdw_hdmi_card_late_probe(struct snd_soc_card *card)
 	if (!ctx->idisp_codec)
 		return 0;
 
+	if (list_empty(&ctx->hdmi_pcm_list))
+		return -EINVAL;
+
 	pcm = list_first_entry(&ctx->hdmi_pcm_list, struct hdmi_pcm,
 			       head);
 	component = pcm->codec_dai->component;
-- 
2.25.1