redonkable
/
alistair23-linux
1
0
Fork 0
Code Releases Activity

ALSA: pcm: Avoid possible info leaks from PCM stream buffers 

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>
alistair/sunxi64-5.5-dsi
Takashi Iwai 2019-12-11 16:57:42 +01:00
parent 5815bdfd7f
commit add9d56d7b
1 changed files with 4 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
sound/core/pcm_native.c
View File

@ -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);