ASoC: dapm: Move dai_link widgets to runtime to fix use after free

The newly added CODEC to CODEC DAI link widget pointers in
snd_soc_dai_link are better placed in snd_soc_pcm_runtime.
snd_soc_dai_link is really intended for static configuration of
the DAI, and the runtime for dynamic data.  The snd_soc_dai_link
structures are not destroyed if the card is unbound. The widgets
are cleared up on unbind, however if the card is rebound as the
snd_soc_dai_link structures are reused these pointers will be left at
their old values, causing access to freed memory.

Fixes: 595571cca4de ("ASoC: dapm: Fix regression introducing multiple copies of DAI widgets")
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20200526161930.30759-1-ckeepax@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/include/sound/soc.h b/include/sound/soc.h
index 946f88a..53e2062 100644 (file)
--- a/include/sound/soc.h
+++ b/include/sound/soc.h
@@ -790,9 +790,6 @@ struct snd_soc_dai_link {
        const struct snd_soc_pcm_stream *params;
        unsigned int num_params;
 
-       struct snd_soc_dapm_widget *playback_widget;
-       struct snd_soc_dapm_widget *capture_widget;
-
        unsigned int dai_fmt;           /* format to set on init */
 
        enum snd_soc_dpcm_trigger trigger[2]; /* trigger type for DPCM */
@@ -1156,6 +1153,9 @@ struct snd_soc_pcm_runtime {
        struct snd_soc_dai **cpu_dais;
        unsigned int num_cpus;
 
+       struct snd_soc_dapm_widget *playback_widget;
+       struct snd_soc_dapm_widget *capture_widget;
+
        struct delayed_work delayed_work;
        void (*close_delayed_work_func)(struct snd_soc_pcm_runtime *rtd);
 #ifdef CONFIG_DEBUG_FS

diff --git a/sound/soc/soc-dapm.c b/sound/soc/soc-dapm.c
index e263284..c0aa64f 100644 (file)
--- a/sound/soc/soc-dapm.c
+++ b/sound/soc/soc-dapm.c
@@ -4340,16 +4340,16 @@ static void dapm_connect_dai_pair(struct snd_soc_card *card,
        codec = codec_dai->playback_widget;
 
        if (playback_cpu && codec) {
-               if (dai_link->params && !dai_link->playback_widget) {
+               if (dai_link->params && !rtd->playback_widget) {
                        substream = streams[SNDRV_PCM_STREAM_PLAYBACK].substream;
                        dai = snd_soc_dapm_new_dai(card, substream, "playback");
                        if (IS_ERR(dai))
                                goto capture;
-                       dai_link->playback_widget = dai;
+                       rtd->playback_widget = dai;
                }
 
                dapm_connect_dai_routes(&card->dapm, cpu_dai, playback_cpu,
-                                       dai_link->playback_widget,
+                                       rtd->playback_widget,
                                        codec_dai, codec);
        }
 
@@ -4358,16 +4358,16 @@ capture:
        codec = codec_dai->capture_widget;
 
        if (codec && capture_cpu) {
-               if (dai_link->params && !dai_link->capture_widget) {
+               if (dai_link->params && !rtd->capture_widget) {
                        substream = streams[SNDRV_PCM_STREAM_CAPTURE].substream;
                        dai = snd_soc_dapm_new_dai(card, substream, "capture");
                        if (IS_ERR(dai))
                                return;
-                       dai_link->capture_widget = dai;
+                       rtd->capture_widget = dai;
                }
 
                dapm_connect_dai_routes(&card->dapm, codec_dai, codec,
-                                       dai_link->capture_widget,
+                                       rtd->capture_widget,
                                        cpu_dai, capture_cpu);
        }
 }