[alsa-devel] [PATCH] ASoC: Fix NULL dereference at freeing

[Takashi Iwai]

When an ASoC driver with pcm_destruct component ops is freed before
the PCM object instantiation (e.g. deferring the probe), it hits an
Oops at snd_soc_pcm_component_free() that calls the pcm_destruct ops
unconditionally.

Fix it by adding a NULL-check of rtd->pcm before calling callbacks.

Fixes: c64bfc906600 ("ASoC: soc-core: add new pcm_construct/pcm_destruct")
Reported-by: Matthias Brugger <matthias.bgg at gmail.com>
Tested-by: Ben Ho <ben.ho at mediatek.com>
Signed-off-by: Takashi Iwai <tiwai at suse.de>
---
 sound/soc/soc-component.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/sound/soc/soc-component.c b/sound/soc/soc-component.c
index 9054558ce386..b94680fb26fa 100644
--- a/sound/soc/soc-component.c
+++ b/sound/soc/soc-component.c
@@ -539,6 +539,9 @@ void snd_soc_pcm_component_free(struct snd_soc_pcm_runtime *rtd)
 	struct snd_soc_rtdcom_list *rtdcom;
 	struct snd_soc_component *component;
 
+	if (!rtd->pcm)
+		return;
+
 	for_each_rtd_components(rtd, rtdcom, component)
 		if (component->driver->pcm_destruct)
 			component->driver->pcm_destruct(component, rtd->pcm);
-- 
2.16.4