[PATCH 5.11 070/601] drm: bridge/panel: Cleanup connector on bridge detach

Greg Kroah-Hartman
2021-05-12T17:02:21Z

From: Paul Cercueil <paul@crapouillou.net>

commit 4d906839d321c2efbf3fed4bc31ffd9ff55b75c0 upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/gpu/drm/bridge/panel.c | 12 ++++++++++++
1 file changed, 12 insertions(+)

--- a/drivers/gpu/drm/bridge/panel.c
+++ b/drivers/gpu/drm/bridge/panel.c
@@ -87,6 +87,18 @@ 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);
}

static void panel_bridge_pre_enable(struct drm_bridge *bridge)