ALSA: PCM: Fix some races at disconnection

Fix races at PCM disconnection:
- while a PCM device is being opened or closed
- while the PCM state is being changed without lock in prepare,
  hw_params, hw_free ops

Reported-by: Matthieu CASTET <matthieu.castet@parrot.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

2 files changed, 18 insertions, 5 deletions

diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index f2991940b271..993b2405fdfe 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -1086,11 +1086,15 @@ static int snd_pcm_dev_disconnect(struct snd_device *device)
         if (list_empty(&pcm->list))
                 goto unlock;
 
+        mutex_lock(&pcm->open_mutex);
         list_del_init(&pcm->list);
         for (cidx = 0; cidx < 2; cidx++)
-                for (substream = pcm->streams[cidx].substream; substream; substream = substream->next)
+                for (substream = pcm->streams[cidx].substream; substream; substream = substream->next) {
+                        snd_pcm_stream_lock_irq(substream);
                         if (substream->runtime)
                                 substream->runtime->status->state = SNDRV_PCM_STATE_DISCONNECTED;
+                        snd_pcm_stream_unlock_irq(substream);
+                }
         list_for_each_entry(notify, &snd_pcm_notify_list, list) {
                 notify->n_disconnect(pcm);
         }
@@ -1110,6 +1114,7 @@ static int snd_pcm_dev_disconnect(struct snd_device *device)
                         pcm->streams[cidx].chmap_kctl = NULL;
                 }
         }
+        mutex_unlock(&pcm->open_mutex);
  unlock:
         mutex_unlock(&register_mutex);
         return 0;
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 5e12e5bacbba..8753c89f3290 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -369,6 +369,14 @@ static int period_to_usecs(struct snd_pcm_runtime *runtime)
         return usecs;
 }
 
+static void snd_pcm_set_state(struct snd_pcm_substream *substream, int state)
+{
+        snd_pcm_stream_lock_irq(substream);
+        if (substream->runtime->status->state != SNDRV_PCM_STATE_DISCONNECTED)
+                substream->runtime->status->state = state;
+        snd_pcm_stream_unlock_irq(substream);
+}
+
 static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
                              struct snd_pcm_hw_params *params)
 {
@@ -452,7 +460,7 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
                 runtime->boundary *= 2;
 
         snd_pcm_timer_resolution_change(substream);
-        runtime->status->state = SNDRV_PCM_STATE_SETUP;
+        snd_pcm_set_state(substream, SNDRV_PCM_STATE_SETUP);
 
         if (pm_qos_request_active(&substream->latency_pm_qos_req))
                 pm_qos_remove_request(&substream->latency_pm_qos_req);
@@ -464,7 +472,7 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
         /* hardware might be unusable from this time,
            so we force application to retry to set
            the correct hardware parameter settings */
-        runtime->status->state = SNDRV_PCM_STATE_OPEN;
+        snd_pcm_set_state(substream, SNDRV_PCM_STATE_OPEN);
         if (substream->ops->hw_free != NULL)
                 substream->ops->hw_free(substream);
         return err;
@@ -512,7 +520,7 @@ static int snd_pcm_hw_free(struct snd_pcm_substream *substream)
                 return -EBADFD;
         if (substream->ops->hw_free)
                 result = substream->ops->hw_free(substream);
-        runtime->status->state = SNDRV_PCM_STATE_OPEN;
+        snd_pcm_set_state(substream, SNDRV_PCM_STATE_OPEN);
         pm_qos_remove_request(&substream->latency_pm_qos_req);
         return result;
 }
@@ -1320,7 +1328,7 @@ static void snd_pcm_post_prepare(struct snd_pcm_substream *substream, int state)
 {
         struct snd_pcm_runtime *runtime = substream->runtime;
         runtime->control->appl_ptr = runtime->status->hw_ptr;
-        runtime->status->state = SNDRV_PCM_STATE_PREPARED;
+        snd_pcm_set_state(substream, SNDRV_PCM_STATE_PREPARED);
 }
 
 static struct action_ops snd_pcm_action_prepare = {