linux-kernel - [PATCH 3/6] ASoC: codecs: wcd939x-sdw: Correct Soundwire ports mask

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Message-Id: <20240726-asoc-wcd-wsa-swr-ports-genmask-v1-3-d4d7a8b56f05@linaro.org>
Date: Fri, 26 Jul 2024 16:10:43 +0200
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>, 
 Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>, 
 Mohammad Rafi Shaik <quic_mohs@...cinc.com>, 
 Prasad Kumpatla <quic_pkumpatl@...cinc.com>, 
 Srinivas Kandagatla <srinivas.kandagatla@...aro.org>, 
 Neil Armstrong <neil.armstrong@...aro.org>, 
 Banajit Goswami <bgoswami@...cinc.com>, 
 Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>, 
 Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc: linux-sound@...r.kernel.org, linux-kernel@...r.kernel.org, 
 alsa-devel@...a-project.org, linux-arm-msm@...r.kernel.org
Subject: [PATCH 3/6] ASoC: codecs: wcd939x-sdw: Correct Soundwire ports
 mask

Device has up to WCD939X_MAX_TX_SWR_PORTS (or WCD939X_MAX_RX_SWR_PORTS
for sink) number of ports and the array assigned to prop.src_dpn_prop
and prop.sink_dpn_prop has 0..WCD939X_MAX_TX_SWR_PORTS-1 elements.  On
the other hand, GENMASK(high, low) creates an inclusive mask between
<high, low>, so we need the mask from 0 up to WCD939X_MAX_TX_SWR_PORTS-1.

Theoretically, too wide mask could cause an out of bounds read in
sdw_get_slave_dpn_prop() in stream.c, however only in the case of buggy
driver, e.g. adding incorrect number of ports via
sdw_stream_add_slave().

Fixes: be2af391cea0 ("ASoC: codecs: Add WCD939x Soundwire devices driver")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>

---

Not adding Cc-stable because I don't think the issue can lead to real
out-of-bounds read.
---
 sound/soc/codecs/wcd939x-sdw.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sound/soc/codecs/wcd939x-sdw.c b/sound/soc/codecs/wcd939x-sdw.c
index 94b1e99a3ca0..fca95777a75a 100644
--- a/sound/soc/codecs/wcd939x-sdw.c
+++ b/sound/soc/codecs/wcd939x-sdw.c
@@ -1453,12 +1453,12 @@ static int wcd9390_probe(struct sdw_slave *pdev, const struct sdw_device_id *id)
 	pdev->prop.lane_control_support = true;
 	pdev->prop.simple_clk_stop_capable = true;
 	if (wcd->is_tx) {
-		pdev->prop.source_ports = GENMASK(WCD939X_MAX_TX_SWR_PORTS, 0);
+		pdev->prop.source_ports = GENMASK(WCD939X_MAX_TX_SWR_PORTS - 1, 0);
 		pdev->prop.src_dpn_prop = wcd939x_tx_dpn_prop;
 		wcd->ch_info = &wcd939x_sdw_tx_ch_info[0];
 		pdev->prop.wake_capable = true;
 	} else {
-		pdev->prop.sink_ports = GENMASK(WCD939X_MAX_RX_SWR_PORTS, 0);
+		pdev->prop.sink_ports = GENMASK(WCD939X_MAX_RX_SWR_PORTS - 1, 0);
 		pdev->prop.sink_dpn_prop = wcd939x_rx_dpn_prop;
 		wcd->ch_info = &wcd939x_sdw_rx_ch_info[0];
 	}

-- 
2.43.0