Re: [Freedreno] [PATCH v2 02/10] drm/msm/dp: 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: 8a3b4c17f863 ("drm/msm/dp: employ bridge mechanism for display enable and disable")
> Cc: stable@xxxxxxxxxxxxxxx	# 5.17
> Signed-off-by: Johan Hovold <johan+linaro@xxxxxxxxxx>
Tested-by: Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>
Reviewed-by: Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>
> ---
>   drivers/gpu/drm/msm/dp/dp_display.c | 6 ++++++
>   1 file changed, 6 insertions(+)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
> index 3e284fed8d30..fbe950edaefe 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -1604,6 +1604,12 @@ int msm_dp_modeset_init(struct msm_dp *dp_display, 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;
> +	}
> +
>   	dp_display->drm_dev = dev;
>   
>   	dp_priv = container_of(dp_display, struct dp_display_private, dp_display);