drm/msm/hdmi: fix memory corruption with too many bridges

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>

diff --git a/drivers/gpu/drm/msm/hdmi/hdmi.c b/drivers/gpu/drm/msm/hdmi/hdmi.c
index 23fb88b5332476bb6f02c4d54b3ed7631ec67fad..e082e01b5e8d1baa4c3c57ab586b6e2f474e3e39 100644 (file)
--- a/drivers/gpu/drm/msm/hdmi/hdmi.c
+++ b/drivers/gpu/drm/msm/hdmi/hdmi.c
@@ -295,6 +295,11 @@ int msm_hdmi_modeset_init(struct hdmi *hdmi,
        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;