Subject: [PATCH 076/104] ALSA: pcm - reject calls to open backend PCMs (temporary)

This stops userspace opening backlemd PCMs.

TODO: rework for upstream.

Signed-off-by: Liam Girdwood <lrg@ti.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index c6698efb44c..0e972485449 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -2036,6 +2036,12 @@ int snd_pcm_open_substream(struct snd_pcm *pcm, int stream,
                 goto error;
         }
 
+        if (substream->ops == NULL) {
+                snd_printd("cannot open back end PCMs directly\n");
+                err = -ENODEV;
+                goto error;
+        }
+
         if ((err = substream->ops->open(substream)) < 0)
                 goto error;