[PATCH AUTOSEL 4.20 15/52] ASoC: topology: fix oops/use-after-free case with dai driver

From: Sasha Levin
Date: Mon Mar 11 2019 - 16:13:11 EST


From: Guennadi Liakhovetski <guennadi.liakhovetski@xxxxxxxxx>

[ Upstream commit 52abe6cc1866ac3d54612f5d80563e6608c0ddfc ]

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@xxxxxxxxx>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
sound/soc/soc-core.c | 2 +-
sound/soc/soc-topology.c | 5 +++++
2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
index 2d49492d6069..c8c6c5a6de8f 100644
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -951,7 +951,7 @@ 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 045ef136903d..fc79ec6927e3 100644
--- 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);
--
2.19.1