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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Richard Fitzgerald <rf@opensource.cirrus.com>,
        Mark Brown <broonie@kernel.org>
Subject: [PATCH 4.15 004/128] ASoC: wm_adsp: For TLV controls only register TLV get/set
Date:   Fri, 16 Mar 2018 16:22:25 +0100
Message-Id: <20180316152336.430113758@linuxfoundation.org>
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4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Richard Fitzgerald <rf@opensource.cirrus.com>

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.

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

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

--- 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 *
 		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;
 	}