[PATCH 1/2] ASoC: soc-devres: add devm_snd_soc_register_dai()

[Pierre-Louis Bossart]

The registration of DAIs may be done at two distinct times, once
during a component registration and later when loading a
topology. Since devm_ managed resources are freed in the reverse order
they were allocated, when a component starts unregistering DAIs by
walking through the DAI list, the memory allocated for the
topology-registered DAIs was freed already, which leads to 100%
reproducible KASAN use-after-free reports.

This patch suggests a new devm_ function to force the DAI list to be
updated prior to freeing the memory chunks referenced by the list
pointers.

BugLink: https://github.com/thesofproject/linux/issues/2186
Suggested-by: Bard Liao <yung-chuan.liao at linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan at linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao at linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen at linux.intel.com>
---
 include/sound/soc.h    |  4 ++++
 sound/soc/soc-devres.c | 37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/include/sound/soc.h b/include/sound/soc.h
index 828baea66b76..2756f9bcac3e 100644
--- a/include/sound/soc.h
+++ b/include/sound/soc.h
@@ -1363,6 +1363,10 @@ void snd_soc_remove_pcm_runtime(struct snd_soc_card *card,
 struct snd_soc_dai *snd_soc_register_dai(struct snd_soc_component *component,
 					 struct snd_soc_dai_driver *dai_drv,
 					 bool legacy_dai_naming);
+struct snd_soc_dai *devm_snd_soc_register_dai(struct device *dev,
+					      struct snd_soc_component *component,
+					      struct snd_soc_dai_driver *dai_drv,
+					      bool legacy_dai_naming);
 void snd_soc_unregister_dai(struct snd_soc_dai *dai);
 
 struct snd_soc_dai *snd_soc_find_dai(
diff --git a/sound/soc/soc-devres.c b/sound/soc/soc-devres.c
index a9ea172a66a7..11e5d7962370 100644
--- a/sound/soc/soc-devres.c
+++ b/sound/soc/soc-devres.c
@@ -9,6 +9,43 @@
 #include <sound/soc.h>
 #include <sound/dmaengine_pcm.h>
 
+static void devm_dai_release(struct device *dev, void *res)
+{
+	snd_soc_unregister_dai(*(struct snd_soc_dai **)res);
+}
+
+/**
+ * devm_snd_soc_register_dai - resource-managed dai registration
+ * @dev: Device used to manage component
+ * @component: The component the DAIs are registered for
+ * @dai_drv: DAI driver to use for the DAI
+ * @legacy_dai_naming: if %true, use legacy single-name format;
+ *	if %false, use multiple-name format;
+ */
+struct snd_soc_dai *devm_snd_soc_register_dai(struct device *dev,
+					      struct snd_soc_component *component,
+					      struct snd_soc_dai_driver *dai_drv,
+					      bool legacy_dai_naming)
+{
+	struct snd_soc_dai **ptr;
+	struct snd_soc_dai *dai;
+
+	ptr = devres_alloc(devm_dai_release, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return NULL;
+
+	dai = snd_soc_register_dai(component, dai_drv, legacy_dai_naming);
+	if (dai) {
+		*ptr = dai;
+		devres_add(dev, ptr);
+	} else {
+		devres_free(ptr);
+	}
+
+	return dai;
+}
+EXPORT_SYMBOL_GPL(devm_snd_soc_register_dai);
+
 static void devm_component_release(struct device *dev, void *res)
 {
 	snd_soc_unregister_component(*(struct device **)res);
-- 
2.20.1