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

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: 8a3b4c1 ("drm/msm/dp: employ bridge mechanism for display enable and disable")
Cc: [email protected]	# 5.17
Signed-off-by: Johan Hovold <[email protected]>
Tested-by: Kuogee Hsieh <[email protected]>
Reviewed-by: Kuogee Hsieh <[email protected]>
Reviewed-by: Dmitry Baryshkov <[email protected]>
Patchwork: https://patchwork.freedesktop.org/patch/502664/
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Abhinav Kumar <[email protected]>

Author: jhovold

drivers/gpu/drm/msm/dp/dp_display.c

@@ -1597,6 +1597,12 @@ 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);