[PATCH 2/6] ASoC: codecs: wcd938x-sdw: Correct Soundwire ports mask

[Krzysztof Kozlowski]

Device has up to WCD938X_MAX_SWR_PORTS number of ports and the array
assigned to prop.src_dpn_prop and prop.sink_dpn_prop has
0..WCD938X_MAX_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 WCD938X_MAX_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: 16572522aece ("ASoC: codecs: wcd938x-sdw: add SoundWire driver")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>

---

Not adding Cc-stable because I don't think the issue can lead to real
out-of-bounds read.
---
 sound/soc/codecs/wcd938x-sdw.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sound/soc/codecs/wcd938x-sdw.c b/sound/soc/codecs/wcd938x-sdw.c
index c995bcc59ead..7da8a10bd0a9 100644
--- a/sound/soc/codecs/wcd938x-sdw.c
+++ b/sound/soc/codecs/wcd938x-sdw.c
@@ -1252,12 +1252,12 @@ static int wcd9380_probe(struct sdw_slave *pdev,
 	pdev->prop.lane_control_support = true;
 	pdev->prop.simple_clk_stop_capable = true;
 	if (wcd->is_tx) {
-		pdev->prop.source_ports = GENMASK(WCD938X_MAX_SWR_PORTS, 0);
+		pdev->prop.source_ports = GENMASK(WCD938X_MAX_SWR_PORTS - 1, 0);
 		pdev->prop.src_dpn_prop = wcd938x_dpn_prop;
 		wcd->ch_info = &wcd938x_sdw_tx_ch_info[0];
 		pdev->prop.wake_capable = true;
 	} else {
-		pdev->prop.sink_ports = GENMASK(WCD938X_MAX_SWR_PORTS, 0);
+		pdev->prop.sink_ports = GENMASK(WCD938X_MAX_SWR_PORTS - 1, 0);
 		pdev->prop.sink_dpn_prop = wcd938x_dpn_prop;
 		wcd->ch_info = &wcd938x_sdw_rx_ch_info[0];
 	}

-- 
2.43.0