ALSA: pcm: Zero-clear reserved fields of PCM status ioctl in compat mode

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@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/sound/core/pcm_compat.c b/sound/core/pcm_compat.c
index af49721ba0e38310183adbe01dcb1f8acaa3d4ab..c4ac3c1e19af9a7b8966271671802b9c8565542e 100644 (file)
--- 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) ||