On Wed, Dec 11, 2019 at 04:57:42PM +0100, Takashi Iwai wrote: > 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. I have tested this patch on the same way I tested the previous one and didn't experience any leakage of data. Thanks for helping putting that together. Kind regards, Lionel > > Reported-by: Lionel Koenig <lionel.koenig@xxxxxxxxx> > Cc: <stable@xxxxxxxxxxxxxxx> > Signed-off-by: Takashi Iwai <tiwai@xxxxxxx> > --- > > This is a revised patch of the previous one > 20191210130219.27919-1-tiwai@xxxxxxx > > 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 1fe581167b7b..d083225344a0 100644 > --- a/sound/core/pcm_native.c > +++ b/sound/core/pcm_native.c > @@ -739,6 +739,10 @@ 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); > _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx https://mailman.alsa-project.org/mailman/listinfo/alsa-devel
