ALSA: compress: info leak in snd_compr_get_caps()

If the ->get_caps() function doesn't clear the buffer then there would
stack information leaked to userspace.  For example,
soc_compr_get_caps() can return success without clearing the buffer.

Change-Id: Ifcd9c95fa949e151039a115f5bd77f7ce6b20a79
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Eric Laurent <elaurent@google.com>
Signed-off-by: Krishnankutty Kolathappilly <kkolat@codeaurora.org>
diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c
index 309697a..5c63466 100644
--- a/sound/core/compress_offload.c
+++ b/sound/core/compress_offload.c
@@ -416,6 +416,7 @@
 	if (!stream->ops->get_caps)
 		return -ENXIO;
 
+	memset(&caps, 0, sizeof(caps));
 	retval = stream->ops->get_caps(stream, &caps);
 	if (retval)
 		goto out;