[alsa-devel] [PATCH 1/3] ASoC: compress: Only call free for components which have been opened

[Charles Keepax]

The core should only call free on a component if said component has
already had open called on it. This is not presently the case and most
compressed drivers in the kernel assume it will be. This causes null
pointer dereferences in the drivers as they attempt clean up for stuff
that was never put in place.

This is fixed by aborting calling open callbacks once a failure is
encountered and then during clean up only iterating through the
component list to that point.

This is a fairly quick fix to the issue, to allow backporting. There
is more refactoring to follow to tidy the code up a little.

Fixes: 9e7e3738ab0e ("ASoC: snd_soc_component_driver has snd_compr_ops")
Signed-off-by: Charles Keepax <ckeepax at opensource.cirrus.com>
---
 sound/soc/soc-compress.c | 52 ++++++++++++++++++++++++++----------------------
 1 file changed, 28 insertions(+), 24 deletions(-)

diff --git a/sound/soc/soc-compress.c b/sound/soc/soc-compress.c
index 82402688bd8e..948505f74229 100644
--- a/sound/soc/soc-compress.c
+++ b/sound/soc/soc-compress.c
@@ -33,7 +33,7 @@ static int soc_compr_open(struct snd_compr_stream *cstream)
 	struct snd_soc_component *component;
 	struct snd_soc_rtdcom_list *rtdcom;
 	struct snd_soc_dai *cpu_dai = rtd->cpu_dai;
-	int ret = 0, __ret;
+	int ret;
 
 	mutex_lock_nested(&rtd->pcm_mutex, rtd->pcm_subclass);
 
@@ -68,16 +68,15 @@ static int soc_compr_open(struct snd_compr_stream *cstream)
 		    !component->driver->compr_ops->open)
 			continue;
 
-		__ret = component->driver->compr_ops->open(cstream);
-		if (__ret < 0) {
+		ret = component->driver->compr_ops->open(cstream);
+		if (ret < 0) {
 			dev_err(component->dev,
 				"Compress ASoC: can't open platform %s: %d\n",
-				component->name, __ret);
-			ret = __ret;
+				component->name, ret);
+			goto machine_err;
 		}
 	}
-	if (ret < 0)
-		goto machine_err;
+	component = NULL;
 
 	if (rtd->dai_link->compr_ops && rtd->dai_link->compr_ops->startup) {
 		ret = rtd->dai_link->compr_ops->startup(cstream);
@@ -97,17 +96,20 @@ static int soc_compr_open(struct snd_compr_stream *cstream)
 
 machine_err:
 	for_each_rtdcom(rtd, rtdcom) {
-		component = rtdcom->component;
+		struct snd_soc_component *err_comp = rtdcom->component;
+
+		if (err_comp == component)
+			break;
 
 		/* ignore duplication for now */
-		if (platform && (component == &platform->component))
+		if (platform && (err_comp == &platform->component))
 			continue;
 
-		if (!component->driver->compr_ops ||
-		    !component->driver->compr_ops->free)
+		if (!err_comp->driver->compr_ops ||
+		    !err_comp->driver->compr_ops->free)
 			continue;
 
-		component->driver->compr_ops->free(cstream);
+		err_comp->driver->compr_ops->free(cstream);
 	}
 
 	if (platform && platform->driver->compr_ops && platform->driver->compr_ops->free)
@@ -132,7 +134,7 @@ static int soc_compr_open_fe(struct snd_compr_stream *cstream)
 	struct snd_soc_dpcm *dpcm;
 	struct snd_soc_dapm_widget_list *list;
 	int stream;
-	int ret = 0, __ret;
+	int ret;
 
 	if (cstream->direction == SND_COMPRESS_PLAYBACK)
 		stream = SNDRV_PCM_STREAM_PLAYBACK;
@@ -172,16 +174,15 @@ static int soc_compr_open_fe(struct snd_compr_stream *cstream)
 		    !component->driver->compr_ops->open)
 			continue;
 
-		__ret = component->driver->compr_ops->open(cstream);
-		if (__ret < 0) {
+		ret = component->driver->compr_ops->open(cstream);
+		if (ret < 0) {
 			dev_err(component->dev,
 				"Compress ASoC: can't open platform %s: %d\n",
-				component->name, __ret);
-			ret = __ret;
+				component->name, ret);
+			goto machine_err;
 		}
 	}
-	if (ret < 0)
-		goto machine_err;
+	component = NULL;
 
 	if (fe->dai_link->compr_ops && fe->dai_link->compr_ops->startup) {
 		ret = fe->dai_link->compr_ops->startup(cstream);
@@ -236,17 +237,20 @@ static int soc_compr_open_fe(struct snd_compr_stream *cstream)
 		fe->dai_link->compr_ops->shutdown(cstream);
 machine_err:
 	for_each_rtdcom(fe, rtdcom) {
-		component = rtdcom->component;
+		struct snd_soc_component *err_comp = rtdcom->component;
+
+		if (err_comp == component)
+			break;
 
 		/* ignore duplication for now */
-		if (platform && (component == &platform->component))
+		if (platform && (err_comp == &platform->component))
 			continue;
 
-		if (!component->driver->compr_ops ||
-		    !component->driver->compr_ops->free)
+		if (!err_comp->driver->compr_ops ||
+		    !err_comp->driver->compr_ops->free)
 			continue;
 
-		component->driver->compr_ops->free(cstream);
+		err_comp->driver->compr_ops->free(cstream);
 	}
 
 	if (platform && platform->driver->compr_ops && platform->driver->compr_ops->free)
-- 
2.11.0