drm: writeback: Fix use after free in drm_writeback_connector_cleanup()

The drm_writeback_cleanup_job() function frees "pos" so call
list_del(&pos->list_entry) first to avoid a use after free.

Fixes: 1914ba2 ("drm: writeback: Create drmm variants for drm_writeback_connector initialization")
Signed-off-by: Dan Carpenter <[email protected]>
Reviewed-by: Dmitry Baryshkov <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Signed-off-by: Maxime Ripard <[email protected]>

Author: Dan Carpenter

drivers/gpu/drm/drm_writeback.c

@@ -360,8 +360,8 @@ static void drm_writeback_connector_cleanup(struct drm_device *dev,
 
 	spin_lock_irqsave(&wb_connector->job_lock, flags);
 	list_for_each_entry_safe(pos, n, &wb_connector->job_queue, list_entry) {
-		drm_writeback_cleanup_job(pos);
 		list_del(&pos->list_entry);
+		drm_writeback_cleanup_job(pos);
 	}
 	spin_unlock_irqrestore(&wb_connector->job_lock, flags);
 }