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authorTakashi Iwai <tiwai@suse.de>2022-05-13 11:00:14 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2022-05-15 19:41:58 +0200
commit9cb6c40a6ebe4a0cfc9d6a181958211682cffea9 (patch)
tree70ad9be033e68a1240d88267635a7915971ee18f /sound/core
parent0779b2efbd63c0a0ccb70d382dfef88ec00ca1ff (diff)
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ALSA: pcm: Fix races among concurrent hw_params and hw_free calls
commit 92ee3c60ec9fe64404dc035e7c41277d74aa26cb upstream. 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> [OP: backport to 4.19: adjusted context] Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'sound/core')
-rw-r--r--sound/core/pcm.c2
-rw-r--r--sound/core/pcm_native.c55
2 files changed, 38 insertions, 19 deletions
diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index b6ed38dec435..a11365dc5349 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -1031,6 +1031,7 @@ 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;
@@ -1062,6 +1063,7 @@ void snd_pcm_detach_substream(struct snd_pcm_substream *substream)
substream->runtime = NULL;
if (substream->timer)
spin_unlock_irq(&substream->timer->lock);
+ 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 c92eca627840..2b46a2ebefe0 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -666,33 +666,40 @@ 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;
params->rmask = ~0U;
err = snd_pcm_hw_refine(substream, params);
@@ -769,14 +776,19 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
if ((usecs = period_to_usecs(runtime)) >= 0)
pm_qos_add_request(&substream->latency_pm_qos_req,
PM_QOS_CPU_DMA_LATENCY, 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 (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);
+ }
+ unlock:
+ mutex_unlock(&runtime->buffer_mutex);
return err;
}
@@ -809,22 +821,27 @@ static int snd_pcm_hw_free(struct snd_pcm_substream *substream)
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;
if (substream->ops->hw_free)
result = substream->ops->hw_free(substream);
snd_pcm_set_state(substream, SNDRV_PCM_STATE_OPEN);
pm_qos_remove_request(&substream->latency_pm_qos_req);
+ unlock:
+ mutex_unlock(&runtime->buffer_mutex);
return result;
}