[PATCH 4.9 18/44] drm/msm/hdmi: fix memory corruption with too many bridges

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Johan Hovold <johan+linaro@kernel.org>

commit 4c1294da6aed1f16d47a417dcfe6602833c3c95c upstream.

Add the missing sanity check on the bridge counter to avoid corrupting
data beyond the fixed-sized bridge array in case there are ever more
than eight bridges.

Fixes: a3376e3ec81c ("drm/msm: convert to drm_bridge")
Cc: stable@vger.kernel.org	# 3.12
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Tested-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Reviewed-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/502670/
Link: https://lore.kernel.org/r/20220913085320.8577-5-johan+linaro@kernel.org
Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/gpu/drm/msm/hdmi/hdmi.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/gpu/drm/msm/hdmi/hdmi.c
+++ b/drivers/gpu/drm/msm/hdmi/hdmi.c
@@ -289,6 +289,11 @@ int msm_hdmi_modeset_init(struct hdmi *h
 	struct platform_device *pdev = hdmi->pdev;
 	int ret;
 
+	if (priv->num_bridges == ARRAY_SIZE(priv->bridges)) {
+		DRM_DEV_ERROR(dev->dev, "too many bridges\n");
+		return -ENOSPC;
+	}
+
 	hdmi->dev = dev;
 	hdmi->encoder = encoder;