[PATCH v4 1/4] ALSA: pcm: unconditionally check if appl_ptr is in 0..boundary range

[Pierre-Louis Bossart]

In some cases, the appl_ptr passed by userspace is not checked before
being used. This patch adds an unconditional check and returns an
error code should the appl_ptr exceed the ALSA 'boundary'.

Suggested-by: Takashi Iwai <tiwai at suse.de>
Reviewed-by: Takashi Iwai <tiwai at suse.de>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan at linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen at linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
---
 sound/core/pcm_lib.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index 4f4b4739f987..fdd992772b20 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -2133,6 +2133,9 @@ int pcm_lib_apply_appl_ptr(struct snd_pcm_substream *substream,
 	if (old_appl_ptr == appl_ptr)
 		return 0;
 
+	if (appl_ptr >= runtime->boundary)
+		return -EINVAL;
+
 	runtime->control->appl_ptr = appl_ptr;
 	if (substream->ops->ack) {
 		ret = substream->ops->ack(substream);
-- 
2.25.1