[PATCH v2 02/10] drm/msm/dp: fix memory corruption with too many bridges

[Johan Hovold]

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>
---
 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);
-- 
2.35.1