[PATCH] ASoC: topology: Check PCM and DAI name strings before use

[Cássio Gabriel]

Topology objects store several PCM and DAI names in fixed-size UAPI
arrays. Other topology parser paths validate these fields with bounded
strnlen() checks before using them as C strings, but the PCM and DAI
paths still pass some fixed-size arrays directly to strlen(),
devm_kstrdup(), DAI lookup, and diagnostic prints.

A malformed topology blob with a non-NUL-terminated PCM, DAI, or stream
capability name can therefore make the parser read past the end of the
fixed-size field.

Reject unterminated PCM and DAI name fields before consuming them as C
strings.

Fixes: 64527e8a3529 ("ASoC: topology: Add FE DAIs dynamically")
Fixes: acfc7d46cddc ("ASoC: topology: Add FE DAI links dynamically")
Fixes: 0038be9a84dc ("ASoC: topology: Add support for configuring existing BE DAIs")
Signed-off-by: Cássio Gabriel <cassiogabrielcontato@xxxxxxxxx>
---
 sound/soc/soc-topology.c | 37 ++++++++++++++++++++++++++++++++++---
 1 file changed, 34 insertions(+), 3 deletions(-)

diff --git a/sound/soc/soc-topology.c b/sound/soc/soc-topology.c
index 85679c8e0229..35cbe29d2275 100644
--- a/sound/soc/soc-topology.c
+++ b/sound/soc/soc-topology.c
@@ -1326,9 +1326,24 @@ static int soc_tplg_dapm_complete(struct soc_tplg *tplg)
 	return ret;
 }
 
+static int soc_tplg_check_name(const char *name)
+{
+	if (strnlen(name, SNDRV_CTL_ELEM_ID_NAME_MAXLEN) ==
+	    SNDRV_CTL_ELEM_ID_NAME_MAXLEN)
+		return -EINVAL;
+
+	return 0;
+}
+
 static int set_stream_info(struct soc_tplg *tplg, struct snd_soc_pcm_stream *stream,
 			   struct snd_soc_tplg_stream_caps *caps)
 {
+	int ret;
+
+	ret = soc_tplg_check_name(caps->name);
+	if (ret)
+		return ret;
+
 	stream->stream_name = devm_kstrdup(tplg->dev, caps->name, GFP_KERNEL);
 	if (!stream->stream_name)
 		return -ENOMEM;
@@ -1380,7 +1395,11 @@ static int soc_tplg_dai_create(struct soc_tplg *tplg,
 	if (dai_drv == NULL)
 		return -ENOMEM;
 
-	if (strlen(pcm->dai_name)) {
+	ret = soc_tplg_check_name(pcm->dai_name);
+	if (ret)
+		goto err;
+
+	if (pcm->dai_name[0]) {
 		dai_drv->name = devm_kstrdup(tplg->dev, pcm->dai_name, GFP_KERNEL);
 		if (!dai_drv->name) {
 			ret = -ENOMEM;
@@ -1486,7 +1505,11 @@ static int soc_tplg_fe_link_create(struct soc_tplg *tplg,
 	if (tplg->ops)
 		link->dobj.unload = tplg->ops->link_unload;
 
-	if (strlen(pcm->pcm_name)) {
+	ret = soc_tplg_check_name(pcm->pcm_name);
+	if (ret)
+		goto err;
+
+	if (pcm->pcm_name[0]) {
 		link->name = devm_kstrdup(tplg->dev, pcm->pcm_name, GFP_KERNEL);
 		link->stream_name = devm_kstrdup(tplg->dev, pcm->pcm_name, GFP_KERNEL);
 		if (!link->name || !link->stream_name) {
@@ -1496,7 +1519,11 @@ static int soc_tplg_fe_link_create(struct soc_tplg *tplg,
 	}
 	link->id = le32_to_cpu(pcm->pcm_id);
 
-	if (strlen(pcm->dai_name)) {
+	ret = soc_tplg_check_name(pcm->dai_name);
+	if (ret)
+		goto err;
+
+	if (pcm->dai_name[0]) {
 		link->cpus->dai_name = devm_kstrdup(tplg->dev, pcm->dai_name, GFP_KERNEL);
 		if (!link->cpus->dai_name) {
 			ret = -ENOMEM;
@@ -1848,6 +1875,10 @@ static int soc_tplg_dai_config(struct soc_tplg *tplg,
 
 	memset(&dai_component, 0, sizeof(dai_component));
 
+	ret = soc_tplg_check_name(d->dai_name);
+	if (ret)
+		return ret;
+
 	dai_component.dai_name = d->dai_name;
 	dai = snd_soc_find_dai(&dai_component);
 	if (!dai) {

---
base-commit: c90ab81b8d75e0ea3d725f60dafed9a8285855f5
change-id: 20260603-asoc-topology-check-pcm-dai-names-0fc80a2181a0

Best regards,
--  
Cássio Gabriel <cassiogabrielcontato@xxxxxxxxx>