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ALSA: pcm: Fix memory leak at closing a stream without hw_free 

ALSA PCM core recently introduced a new managed PCM buffer allocation
mode that does allocate / free automatically at hw_params and
hw_free.  However, it overlooked the code path directly calling
hw_free PCM ops at releasing the PCM substream, and it may result in a
memory leak as spotted by syzkaller when no buffer preallocation is
used (e.g. vmalloc buffer).

This patch papers over it with a slight refactoring.  The hw_free ops
call and relevant tasks are unified in a new helper function, and call
it from both places.

Fixes: 0dba808eae ("ALSA: pcm: Introduce managed buffer allocation mode")
Reported-by: syzbot+30edd0f34bfcdc548ac4@syzkaller.appspotmail.com
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200129195907.12197-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2020-01-29 20:59:07 +01:00
parent 46b770f720
commit 66f2d19f81
1 changed files with 15 additions and 9 deletions
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24
sound/core/pcm_native.c
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@ -786,10 +786,22 @@ static int snd_pcm_hw_params_user(struct snd_pcm_substream *substream,
return err;
}
static int do_hw_free(struct snd_pcm_substream *substream)
{
int result = 0;
snd_pcm_sync_stop(substream);
if (substream->ops->hw_free)
result = substream->ops->hw_free(substream);
if (substream->managed_buffer_alloc)
snd_pcm_lib_free_pages(substream);
return result;
}
static int snd_pcm_hw_free(struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime;
int result = 0;
int result;
if (PCM_RUNTIME_CHECK(substream))
return -ENXIO;
@ -806,11 +818,7 @@ static int snd_pcm_hw_free(struct snd_pcm_substream *substream)
snd_pcm_stream_unlock_irq(substream);
if (atomic_read(&substream->mmap_count))
return -EBADFD;
snd_pcm_sync_stop(substream);
if (substream->ops->hw_free)
result = substream->ops->hw_free(substream);
if (substream->managed_buffer_alloc)
snd_pcm_lib_free_pages(substream);
result = do_hw_free(substream);
snd_pcm_set_state(substream, SNDRV_PCM_STATE_OPEN);
pm_qos_remove_request(&substream->latency_pm_qos_req);
return result;
@ -2529,9 +2537,7 @@ void snd_pcm_release_substream(struct snd_pcm_substream *substream)
snd_pcm_drop(substream);
if (substream->hw_opened) {
if (substream->ops->hw_free &&
substream->runtime->status->state != SNDRV_PCM_STATE_OPEN)
substream->ops->hw_free(substream);
do_hw_free(substream);
substream->ops->close(substream);
substream->hw_opened = 0;
}