ASoC: topology: fix oops/use-after-free case with dai driver

rmmod/modprobe tests expose a kernel oops when accessing the dai
driver pointer. This comes from the topology design which operates in
multiple passes. Each object removal happens at a specific iteration,
and the code checks for the iteration (order) number after the memory
containing the order was freed.

Fix this be clearing a reference to the dai driver and check its
validity to avoid dereferences.

Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
index ea16c2b..50617db 100644 (file)
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -956,7 +956,7 @@ static void soc_remove_dai(struct snd_soc_dai *dai, int order)
 {
        int err;
 
-       if (!dai || !dai->probed ||
+       if (!dai || !dai->probed || !dai->driver ||
            dai->driver->remove_order != order)
                return;
 

diff --git a/sound/soc/soc-topology.c b/sound/soc/soc-topology.c
index 045ef13..fc79ec6 100644 (file)
--- a/sound/soc/soc-topology.c
+++ b/sound/soc/soc-topology.c
@@ -502,6 +502,7 @@ static void remove_dai(struct snd_soc_component *comp,
 {
        struct snd_soc_dai_driver *dai_drv =
                container_of(dobj, struct snd_soc_dai_driver, dobj);
+       struct snd_soc_dai *dai;
 
        if (pass != SOC_TPLG_PASS_PCM_DAI)
                return;
@@ -509,6 +510,10 @@ static void remove_dai(struct snd_soc_component *comp,
        if (dobj->ops && dobj->ops->dai_unload)
                dobj->ops->dai_unload(comp, dobj);
 
+       list_for_each_entry(dai, &comp->dai_list, list)
+               if (dai->driver == dai_drv)
+                       dai->driver = NULL;
+
        kfree(dai_drv->name);
        list_del(&dobj->list);
        kfree(dai_drv);