ALSA: pcm: Don't embed device

So far we use the embedded struct device for each PCM substreams in
struct snd_pcm.  This may result in UAF when the delayed kobj release
is used; each corresponding struct device is still accessed at the
(delayed) device release, while the snd_pcm object may be already
gone.

As a workaround, detach the struct device from the snd_pcm object by
allocating via the new snd_device_alloc() helper.

A caveat is that we store the PCM substream pointer to drvdata since
the device resume and others require the access to it.

This patch is based on the fix Curtis posted initially.  In this
patch, the changes are split and use the new helper function instead.

Link: https://lore.kernel.org/r/20230801171928.1460120-1-cujomalainey@chromium.org
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Curtis Malainey <cujomalainey@chromium.org>
Tested-by: Curtis Malainey <cujomalainey@chromium.org>
Link: https://lore.kernel.org/r/20230816160252.23396-4-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index 19f564606ac42edc8c437b7e458ca1e935204182..0243a13e9ac476d57f5699ca1a02651bb853fdf3 100644 (file)
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -510,7 +510,7 @@ struct snd_pcm_str {
 #endif
 #endif
        struct snd_kcontrol *chmap_kctl; /* channel-mapping controls */
-       struct device dev;
+       struct device *dev;
 };
 
 struct snd_pcm {

diff --git a/sound/aoa/soundbus/i2sbus/pcm.c b/sound/aoa/soundbus/i2sbus/pcm.c
index a9e502a6cdeb89f7fb695528a80937a1b63eb1ed..3680eb6eabc9dab1a1a919845f6d681ecfda1413 100644 (file)
--- a/sound/aoa/soundbus/i2sbus/pcm.c
+++ b/sound/aoa/soundbus/i2sbus/pcm.c
@@ -972,7 +972,7 @@ i2sbus_attach_codec(struct soundbus_dev *dev, struct snd_card *card,
                        goto out_put_ci_module;
                snd_pcm_set_ops(dev->pcm, SNDRV_PCM_STREAM_PLAYBACK,
                                &i2sbus_playback_ops);
-               dev->pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].dev.parent =
+               dev->pcm->streams[SNDRV_PCM_STREAM_PLAYBACK]->dev.parent =
                        &dev->ofdev.dev;
                i2sdev->out.created = 1;
        }
@@ -989,7 +989,7 @@ i2sbus_attach_codec(struct soundbus_dev *dev, struct snd_card *card,
                        goto out_put_ci_module;
                snd_pcm_set_ops(dev->pcm, SNDRV_PCM_STREAM_CAPTURE,
                                &i2sbus_record_ops);
-               dev->pcm->streams[SNDRV_PCM_STREAM_CAPTURE].dev.parent =
+               dev->pcm->streams[SNDRV_PCM_STREAM_CAPTURE]->dev.parent =
                        &dev->ofdev.dev;
                i2sdev->in.created = 1;
        }

diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index 1c0bb3a07bff7f435e8a81db45069e2c1c34ba7c..20bb2d7c8d4bf6cde42153cdbb7a16a0cd2bbb75 100644 (file)
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -604,7 +604,7 @@ static const struct attribute_group *pcm_dev_attr_groups[];
 #ifdef CONFIG_PM_SLEEP
 static int do_pcm_suspend(struct device *dev)
 {
-       struct snd_pcm_str *pstr = container_of(dev, struct snd_pcm_str, dev);
+       struct snd_pcm_str *pstr = dev_get_drvdata(dev);
 
        if (!pstr->pcm->no_device_suspend)
                snd_pcm_suspend_all(pstr->pcm);
@@ -650,11 +650,14 @@ int snd_pcm_new_stream(struct snd_pcm *pcm, int stream, int substream_count)
        if (!substream_count)
                return 0;
 
-       snd_device_initialize(&pstr->dev, pcm->card);
-       pstr->dev.groups = pcm_dev_attr_groups;
-       pstr->dev.type = &pcm_dev_type;
-       dev_set_name(&pstr->dev, "pcmC%iD%i%c", pcm->card->number, pcm->device,
+       err = snd_device_alloc(&pstr->dev, pcm->card);
+       if (err < 0)
+               return err;
+       dev_set_name(pstr->dev, "pcmC%iD%i%c", pcm->card->number, pcm->device,
                     stream == SNDRV_PCM_STREAM_PLAYBACK ? 'p' : 'c');
+       pstr->dev->groups = pcm_dev_attr_groups;
+       pstr->dev->type = &pcm_dev_type;
+       dev_set_drvdata(pstr->dev, pstr);
 
        if (!pcm->internal) {
                err = snd_pcm_stream_proc_init(pstr);
@@ -845,7 +848,7 @@ static void snd_pcm_free_stream(struct snd_pcm_str * pstr)
 #endif
        free_chmap(pstr);
        if (pstr->substream_count)
-               put_device(&pstr->dev);
+               put_device(pstr->dev);
 }
 
 #if IS_ENABLED(CONFIG_SND_PCM_OSS)
@@ -1015,7 +1018,7 @@ void snd_pcm_detach_substream(struct snd_pcm_substream *substream)
 static ssize_t pcm_class_show(struct device *dev,
                              struct device_attribute *attr, char *buf)
 {
-       struct snd_pcm_str *pstr = container_of(dev, struct snd_pcm_str, dev);
+       struct snd_pcm_str *pstr = dev_get_drvdata(dev);
        struct snd_pcm *pcm = pstr->pcm;
        const char *str;
        static const char *strs[SNDRV_PCM_CLASS_LAST + 1] = {
@@ -1076,7 +1079,7 @@ static int snd_pcm_dev_register(struct snd_device *device)
                /* register pcm */
                err = snd_register_device(devtype, pcm->card, pcm->device,
                                          &snd_pcm_f_ops[cidx], pcm,
-                                         &pcm->streams[cidx].dev);
+                                         pcm->streams[cidx].dev);
                if (err < 0) {
                        list_del_init(&pcm->list);
                        goto unlock;
@@ -1123,7 +1126,8 @@ static int snd_pcm_dev_disconnect(struct snd_device *device)
 
        pcm_call_notify(pcm, n_disconnect);
        for (cidx = 0; cidx < 2; cidx++) {
-               snd_unregister_device(&pcm->streams[cidx].dev);
+               if (pcm->streams[cidx].dev)
+                       snd_unregister_device(pcm->streams[cidx].dev);
                free_chmap(&pcm->streams[cidx]);
        }
        mutex_unlock(&pcm->open_mutex);

diff --git a/sound/usb/media.c b/sound/usb/media.c
index 6d11fedb463262f82a88109894d4bd2685273d60..d48db6f3ae659d30cc962f266631ef2115151dc9 100644 (file)
--- a/sound/usb/media.c
+++ b/sound/usb/media.c
@@ -35,7 +35,7 @@ int snd_media_stream_init(struct snd_usb_substream *subs, struct snd_pcm *pcm,
 {
        struct media_device *mdev;
        struct media_ctl *mctl;
-       struct device *pcm_dev = &pcm->streams[stream].dev;
+       struct device *pcm_dev = pcm->streams[stream].dev;
        u32 intf_type;
        int ret = 0;
        u16 mixer_pad;