The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
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: [PATCH] drm: bridge/panel: Cleanup connector on bridge detach
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@cr...
diff --git a/drivers/gpu/drm/bridge/panel.c b/drivers/gpu/drm/bridge/panel.c index 0ddc37551194..c916f4b8907e 100644 --- a/drivers/gpu/drm/bridge/panel.c +++ b/drivers/gpu/drm/bridge/panel.c @@ -87,6 +87,18 @@ static int panel_bridge_attach(struct drm_bridge *bridge,
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)