Patch "ASoC: wm_adsp: For TLV controls only register TLV get/set" has been added to the 4.15-stable tree

This is a note to let you know that I've just added the patch titled

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

to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
asoc-wm_adsp-for-tlv-controls-only-register-tlv-get-set.patch
and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Richard Fitzgerald <[email protected]>
Date: Wed, 28 Feb 2018 10:31:10 +0000
Subject: ASoC: wm_adsp: For TLV controls only register TLV get/set

From: Richard Fitzgerald <[email protected]>

commit d7789f5bcdb298c4a302db471b1b20f74a20de95 upstream.

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.

---
 sound/soc/codecs/wm_adsp.c |   14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

@@ -1204,12 +1204,14 @@ static int wmfw_add_ctl(struct wm_adsp *
 		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;
 	}
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.15/asoc-wm_adsp-for-tlv-controls-only-register-tlv-get-set.patch