[PATCH 3.12 072/206] ALSA: pcm: Zero-clear reserved fields of PCM status ioctl in compat mode

From: Jiri Slaby
Date: Tue Nov 18 2014 - 10:03:29 EST

From: Takashi Iwai <tiwai@xxxxxxx>

3.12-stable review patch. If anyone has any objections, please let me know.


commit 317168d0c766defd14b3d0e9c2c4a9a258b803ee upstream.

In compat mode, we copy each field of snd_pcm_status struct but don't
touch the reserved fields, and this leaves uninitialized values
there. Meanwhile the native ioctl does zero-clear the whole
structure, so we should follow the same rule in compat mode, too.

Reported-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
sound/core/pcm_compat.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/sound/core/pcm_compat.c b/sound/core/pcm_compat.c
index af49721ba0e3..c4ac3c1e19af 100644
--- a/sound/core/pcm_compat.c
+++ b/sound/core/pcm_compat.c
@@ -206,6 +206,8 @@ static int snd_pcm_status_user_compat(struct snd_pcm_substream *substream,
if (err < 0)
return err;

+ if (clear_user(src, sizeof(*src)))
+ return -EFAULT;
if (put_user(status.state, &src->state) ||
compat_put_timespec(&status.trigger_tstamp, &src->trigger_tstamp) ||
compat_put_timespec(&status.tstamp, &src->tstamp) ||

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