From: Takashi Iwai tiwai@suse.de
commit add9d56d7b3781532208afbff5509d7382fb6efe upstream.
The current PCM code doesn't initialize explicitly the buffers allocated for PCM streams, hence it might leak some uninitialized kernel data or previous stream contents by mmapping or reading the buffer before actually starting the stream.
Since this is a common problem, this patch simply adds the clearance of the buffer data at hw_params callback. Although this does only zero-clear no matter which format is used, which doesn't mean the silence for some formats, but it should be OK because the intention is just to clear the previous data on the buffer.
Reported-by: Lionel Koenig lionel.koenig@gmail.com Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20191211155742.3213-1-tiwai@suse.de Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- sound/core/pcm_native.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index e08c6c6..f03ceaf 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -752,6 +752,10 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream, while (runtime->boundary * 2 <= LONG_MAX - runtime->buffer_size) runtime->boundary *= 2;
+ /* clear the buffer for avoiding possible kernel info leaks */ + if (runtime->dma_area && !substream->ops->copy_user) + memset(runtime->dma_area, 0, runtime->dma_bytes); + snd_pcm_timer_resolution_change(substream); snd_pcm_set_state(substream, SNDRV_PCM_STATE_SETUP);