ASoC: core: Do not call link_exit() on uninitialized rtd objects

On init we have sequence:

	for_each_card_prelinks(card, i, dai_link) {
		ret = snd_soc_add_pcm_runtime(card, dai_link);

	ret = init_some_other_things(...);
	if (ret)
		goto probe_end:

	for_each_card_rtds(card, rtd) {
		ret = soc_init_pcm_runtime(card, rtd);

probe_end:

while on exit:
	for_each_card_rtds(card, rtd)
		snd_soc_link_exit(rtd);

If init_some_other_things() step fails due to error we end up with
not fully setup rtds and try to call snd_soc_link_exit on them, which
depending on contents on .link_exit handler, can end up dereferencing
NULL pointer.

Reviewed-by: Cezary Rojewski <[email protected]>
Signed-off-by: Amadeusz Sławiński <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mark Brown <[email protected]>

Author: Amadeusz Sławiński

include/sound/soc.h

@@ -1126,6 +1126,8 @@ struct snd_soc_pcm_runtime {
 	unsigned int pop_wait:1;
 	unsigned int fe_compr:1; /* for Dynamic PCM */
 
+	bool initialized;
+
 	int num_components;
 	struct snd_soc_component *components[]; /* CPU/Codec/Platform */
 };

sound/soc/soc-core.c

@@ -1347,7 +1347,7 @@ static int soc_init_pcm_runtime(struct snd_soc_card *card,
 	snd_soc_runtime_get_dai_fmt(rtd);
 	ret = snd_soc_runtime_set_dai_fmt(rtd, dai_link->dai_fmt);
 	if (ret)
-		return ret;
+		goto err;
 
 	/* add DPCM sysfs entries */
 	soc_dpcm_debugfs_add(rtd);
@@ -1372,17 +1372,26 @@ static int soc_init_pcm_runtime(struct snd_soc_card *card,
 	/* create compress_device if possible */
 	ret = snd_soc_dai_compress_new(cpu_dai, rtd, num);
 	if (ret != -ENOTSUPP)
-		return ret;
+		goto err;
 
 	/* create the pcm */
 	ret = soc_new_pcm(rtd, num);
 	if (ret < 0) {
 		dev_err(card->dev, "ASoC: can't create pcm %s :%d\n",
 			dai_link->stream_name, ret);
-		return ret;
+		goto err;
 	}
 
-	return snd_soc_pcm_dai_new(rtd);
+	ret = snd_soc_pcm_dai_new(rtd);
+	if (ret < 0)
+		goto err;
+
+	rtd->initialized = true;
+
+	return 0;
+err:
+	snd_soc_link_exit(rtd);
+	return ret;
 }
 
 static void soc_set_name_prefix(struct snd_soc_card *card,
@@ -1980,7 +1989,8 @@ static void soc_cleanup_card_resources(struct snd_soc_card *card)
 
 	/* release machine specific resources */
 	for_each_card_rtds(card, rtd)
-		snd_soc_link_exit(rtd);
+		if (rtd->initialized)
+			snd_soc_link_exit(rtd);
 	/* remove and free each DAI */
 	soc_remove_link_dais(card);
 	soc_remove_link_components(card);