From 74466e46e7543c7f74f1502181e9ba93f7521374 Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan+linaro@kernel.org>
Date: Tue, 13 Sep 2022 10:53:12 +0200
Subject: drm/msm/dp: fix memory corruption with too many bridges
Git-commit: 74466e46e7543c7f74f1502181e9ba93f7521374
Patch-mainline: v6.1-rc3
References: git-fixes

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@vger.kernel.org	# 5.17
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/502664/
Link: https://lore.kernel.org/r/20220913085320.8577-3-johan+linaro@kernel.org
Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 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 bfd0aeff3f0d..be9ed891dc3f 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/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);
-- 
2.39.0