ASoC: wm_adsp: For TLV controls only register TLV get/set

Normal 512-byte get/set of a TLV isn't supported but we were
registering the normal get/set anyway and relying on omitting
the SNDRV_CTL_ELEM_ACCESS_[READ|WRITE] flags to prevent them
being called.

Trouble is if this gets broken in the core ALSA code - as it has
been since at least 4.14 - the standard get/set can be called
unexpectedly and corrupt memory.

There's no point providing functions that won't be called and
it's a trivial change. The benefit is that if the ALSA core gets
broken again we get a big fat immediate NULL dereference instead
of a memory corruption timebomb.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org

1 files changed, 8 insertions, 6 deletions

diff --git a/sound/soc/codecs/wm_adsp.c b/sound/soc/codecs/wm_adsp.c
index 66e32f5d2917..989d093abda7 100644
--- a/sound/soc/codecs/wm_adsp.c
+++ b/sound/soc/codecs/wm_adsp.c
@@ -1204,12 +1204,14 @@ static int wmfw_add_ctl(struct wm_adsp *dsp, struct wm_coeff_ctl *ctl)
                 kcontrol->put = wm_coeff_put_acked;
                 break;
         default:
-                kcontrol->get = wm_coeff_get;
-                kcontrol->put = wm_coeff_put;
-
-                ctl->bytes_ext.max = ctl->len;
-                ctl->bytes_ext.get = wm_coeff_tlv_get;
-                ctl->bytes_ext.put = wm_coeff_tlv_put;
+                if (kcontrol->access & SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK) {
+                        ctl->bytes_ext.max = ctl->len;
+                        ctl->bytes_ext.get = wm_coeff_tlv_get;
+                        ctl->bytes_ext.put = wm_coeff_tlv_put;
+                } else {
+                        kcontrol->get = wm_coeff_get;
+                        kcontrol->put = wm_coeff_put;
+                }
                 break;
         }