[PATCH 2/7] drm/msm: fix memory corruption with too many bridges

Johan Hovold
2022-09-12T15:41:36Z

Add the missing sanity checks on the bridge counter to avoid corrupting
data beyond the fixed-sized bridge array in case there are ever more
than eight bridges.

a3376e3ec81c ("drm/msm: convert to drm_bridge")
ab5b0107ccf3 ("drm/msm: Initial add eDP support in msm drm driver (v5)")
a689554ba6ed ("drm/msm: Initial add DSI connector support")
Fixes: 8a3b4c17f863 ("drm/msm/dp: employ bridge mechanism for display enable and disable")
Cc: stable@vger.kernel.org # 3.12
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
---
drivers/gpu/drm/msm/dp/dp_display.c | 6 ++++++
drivers/gpu/drm/msm/dsi/dsi.c | 6 ++++++
drivers/gpu/drm/msm/hdmi/hdmi.c | 5 +++++
3 files changed, 17 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);
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);
diff --git a/drivers/gpu/drm/msm/hdmi/hdmi.c b/drivers/gpu/drm/msm/hdmi/hdmi.c
index 93fe61b86967..a0ed6aa8e4e1 100644
--- a/drivers/gpu/drm/msm/hdmi/hdmi.c
+++ b/drivers/gpu/drm/msm/hdmi/hdmi.c
@@ -300,6 +300,11 @@ int msm_hdmi_modeset_init(struct hdmi *hdmi,
struct platform_device *pdev = hdmi->pdev;
int ret;

+ if (priv->num_bridges == ARRAY_SIZE(priv->bridges)) {
+ DRM_DEV_ERROR(dev->dev, "too many bridges\n");
+ return -ENOSPC;
+ }
+
hdmi->dev = dev;
hdmi->encoder = encoder;

--
2.35.1