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authorTakashi Iwai <tiwai@suse.de>2022-03-22 18:07:17 +0100
committerTakashi Iwai <tiwai@suse.de>2022-03-22 20:56:07 +0100
commit92ee3c60ec9fe64404dc035e7c41277d74aa26cb (patch)
tree495dbd456ef721512b0113483cc62e34879e6d6c /sound
parent646b907e1559f006c79a752ee3eebe220ceb983d (diff)
ALSA: pcm: Fix races among concurrent hw_params and hw_free calls
Currently we have neither proper check nor protection against the concurrent calls of PCM hw_params and hw_free ioctls, which may result in a UAF. Since the existing PCM stream lock can't be used for protecting the whole ioctl operations, we need a new mutex to protect those racy calls. This patch introduced a new mutex, runtime->buffer_mutex, and applies it to both hw_params and hw_free ioctl code paths. Along with it, the both functions are slightly modified (the mmap_count check is moved into the state-check block) for code simplicity. Reported-by: Hu Jiahui <kirin.say@gmail.com> Cc: <stable@vger.kernel.org> Reviewed-by: Jaroslav Kysela <perex@perex.cz> Link: https://lore.kernel.org/r/20220322170720.3529-2-tiwai@suse.de Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound')
-rw-r--r--sound/core/pcm.c2
-rw-r--r--sound/core/pcm_native.c61
2 files changed, 41 insertions, 22 deletions
diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index ba4a987ed1c6..edd9849210f2 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -969,6 +969,7 @@ int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream,
init_waitqueue_head(&runtime->tsleep);
runtime->status->state = SNDRV_PCM_STATE_OPEN;
+ mutex_init(&runtime->buffer_mutex);
substream->runtime = runtime;
substream->private_data = pcm->private_data;
@@ -1002,6 +1003,7 @@ void snd_pcm_detach_substream(struct snd_pcm_substream *substream)
} else {
substream->runtime = NULL;
}
+ mutex_destroy(&runtime->buffer_mutex);
kfree(runtime);
put_pid(substream->pid);
substream->pid = NULL;
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index a056b3ef3c84..266895374b83 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -685,33 +685,40 @@ static int snd_pcm_hw_params_choose(struct snd_pcm_substream *pcm,
return 0;
}
+#if IS_ENABLED(CONFIG_SND_PCM_OSS)
+#define is_oss_stream(substream) ((substream)->oss.oss)
+#else
+#define is_oss_stream(substream) false
+#endif
+
static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
struct snd_pcm_hw_params *params)
{
struct snd_pcm_runtime *runtime;
- int err, usecs;
+ int err = 0, usecs;
unsigned int bits;
snd_pcm_uframes_t frames;
if (PCM_RUNTIME_CHECK(substream))
return -ENXIO;
runtime = substream->runtime;
+ mutex_lock(&runtime->buffer_mutex);
snd_pcm_stream_lock_irq(substream);
switch (runtime->status->state) {
case SNDRV_PCM_STATE_OPEN:
case SNDRV_PCM_STATE_SETUP:
case SNDRV_PCM_STATE_PREPARED:
+ if (!is_oss_stream(substream) &&
+ atomic_read(&substream->mmap_count))
+ err = -EBADFD;
break;
default:
- snd_pcm_stream_unlock_irq(substream);
- return -EBADFD;
+ err = -EBADFD;
+ break;
}
snd_pcm_stream_unlock_irq(substream);
-#if IS_ENABLED(CONFIG_SND_PCM_OSS)
- if (!substream->oss.oss)
-#endif
- if (atomic_read(&substream->mmap_count))
- return -EBADFD;
+ if (err)
+ goto unlock;
snd_pcm_sync_stop(substream, true);
@@ -799,16 +806,21 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
if (usecs >= 0)
cpu_latency_qos_add_request(&substream->latency_pm_qos_req,
usecs);
- return 0;
+ err = 0;
_error:
- /* hardware might be unusable from this time,
- so we force application to retry to set
- the correct hardware parameter settings */
- snd_pcm_set_state(substream, SNDRV_PCM_STATE_OPEN);
- if (substream->ops->hw_free != NULL)
- substream->ops->hw_free(substream);
- if (substream->managed_buffer_alloc)
- snd_pcm_lib_free_pages(substream);
+ if (err) {
+ /* hardware might be unusable from this time,
+ * so we force application to retry to set
+ * the correct hardware parameter settings
+ */
+ snd_pcm_set_state(substream, SNDRV_PCM_STATE_OPEN);
+ if (substream->ops->hw_free != NULL)
+ substream->ops->hw_free(substream);
+ if (substream->managed_buffer_alloc)
+ snd_pcm_lib_free_pages(substream);
+ }
+ unlock:
+ mutex_unlock(&runtime->buffer_mutex);
return err;
}
@@ -848,26 +860,31 @@ static int do_hw_free(struct snd_pcm_substream *substream)
static int snd_pcm_hw_free(struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime;
- int result;
+ int result = 0;
if (PCM_RUNTIME_CHECK(substream))
return -ENXIO;
runtime = substream->runtime;
+ mutex_lock(&runtime->buffer_mutex);
snd_pcm_stream_lock_irq(substream);
switch (runtime->status->state) {
case SNDRV_PCM_STATE_SETUP:
case SNDRV_PCM_STATE_PREPARED:
+ if (atomic_read(&substream->mmap_count))
+ result = -EBADFD;
break;
default:
- snd_pcm_stream_unlock_irq(substream);
- return -EBADFD;
+ result = -EBADFD;
+ break;
}
snd_pcm_stream_unlock_irq(substream);
- if (atomic_read(&substream->mmap_count))
- return -EBADFD;
+ if (result)
+ goto unlock;
result = do_hw_free(substream);
snd_pcm_set_state(substream, SNDRV_PCM_STATE_OPEN);
cpu_latency_qos_remove_request(&substream->latency_pm_qos_req);
+ unlock:
+ mutex_unlock(&runtime->buffer_mutex);
return result;
}