From 4d906839d321c2efbf3fed4bc31ffd9ff55b75c0 Mon Sep 17 00:00:00 2001
From: Paul Cercueil <paul@crapouillou.net>
Date: Sat, 27 Mar 2021 11:57:40 +0000
Subject: drm: bridge/panel: Cleanup connector on bridge detach
Git-commit: 4d906839d321c2efbf3fed4bc31ffd9ff55b75c0
Patch-mainline: v5.13-rc1
References: bsc#1220777, CVE-2021-47063
If we don't call drm_connector_cleanup() manually in
panel_bridge_detach(), the connector will be cleaned up with the other
DRM objects in the call to drm_mode_config_cleanup(). However, since our
drm_connector is devm-allocated, by the time drm_mode_config_cleanup()
will be called, our connector will be long gone. Therefore, the
connector must be cleaned up when the bridge is detached to avoid
use-after-free conditions.
v2: Cleanup connector only if it was created
v3: Add FIXME
v4: (Use connector->dev) directly in if() block
Fixes: 13dfc0540a57 ("drm/bridge: Refactor out the panel wrapper from the lvds-encoder bridge.")
Cc: <stable@vger.kernel.org> # 4.12+
Cc: Andrzej Hajda <a.hajda@samsung.com>
Cc: Neil Armstrong <narmstrong@baylibre.com>
Cc: Laurent Pinchart <Laurent.pinchart@ideasonboard.com>
Cc: Jonas Karlman <jonas@kwiboo.se>
Cc: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210327115742.18986-2-paul@crapouillou.net
Acked-by: Thomas Zimmermann <tzimmermann@suse.com>
---
drivers/gpu/drm/bridge/panel.c | 11 +++++++++++
1 file changed, 11 insertions(+)
--- a/drivers/gpu/drm/bridge/panel.c
+++ b/drivers/gpu/drm/bridge/panel.c
@@ -92,6 +92,17 @@ static int panel_bridge_attach(struct dr
static void panel_bridge_detach(struct drm_bridge *bridge)
{
struct panel_bridge *panel_bridge = drm_bridge_to_panel_bridge(bridge);
+ struct drm_connector *connector = &panel_bridge->connector;
+
+ /*
+ * Cleanup the connector if we know it was initialized.
+ *
+ * FIXME: This wouldn't be needed if the panel_bridge structure was
+ * allocated with drmm_kzalloc(). This might be tricky since the
+ * drm_device pointer can only be retrieved when the bridge is attached.
+ */
+ if (connector->dev)
+ drm_connector_cleanup(connector);
drm_panel_detach(panel_bridge->panel);
}