[PATCH v2 03/10] drm/msm/dsi: fix memory corruption with too many bridges

[Kuogee Hsieh]

On 9/13/2022 1:53 AM, Johan Hovold wrote:
> 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: a689554ba6ed ("drm/msm: Initial add DSI connector support")
> Cc: stable at vger.kernel.org	# 4.1
> Signed-off-by: Johan Hovold <johan+linaro at kernel.org>
Tested-by: Kuogee Hsieh <quic_khsieh at quicinc.com>
Reviewed-by: Kuogee Hsieh <quic_khsieh at quicinc.com>
> ---
>   drivers/gpu/drm/msm/dsi/dsi.c | 6 ++++++
>   1 file changed, 6 insertions(+)
>
> diff --git a/drivers/gpu/drm/msm/dsi/dsi.c b/drivers/gpu/drm/msm/dsi/dsi.c
> index 39bbabb5daf6..8a95c744972a 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi.c
> +++ b/drivers/gpu/drm/msm/dsi/dsi.c
> @@ -218,6 +218,12 @@ int msm_dsi_modeset_init(struct msm_dsi *msm_dsi, struct drm_device *dev,
>   		return -EINVAL;
>   
>   	priv = dev->dev_private;
> +
> +	if (priv->num_bridges == ARRAY_SIZE(priv->bridges)) {
> +		DRM_DEV_ERROR(dev->dev, "too many bridges\n");
> +		return -ENOSPC;
> +	}
> +
>   	msm_dsi->dev = dev;
>   
>   	ret = msm_dsi_host_modeset_init(msm_dsi->host, dev);