drm/gma500: Fix end of loop tests for list_for_each_entry

The list_for_each_entry() iterator, "connector" in this code, can never be
NULL.  If we exit the loop without finding the correct  connector then
"connector" points invalid memory that is an offset from the list head.
This will eventually lead to memory corruption and presumably a kernel
crash.

Fixes: 9bd81acdb648 ("gma500: Convert Oaktrail to work with new output handling")
Signed-off-by: Harshvardhan Jha <harshvardhan.jha@oracle.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210709073959.11443-1-harshvardhan.jha@oracle.com

diff --git a/drivers/gpu/drm/gma500/oaktrail_lvds.c b/drivers/gpu/drm/gma500/oaktrail_lvds.c
index 1f2f892961d60f6aec47862f1a5b5bbf7e67bf89..f9b1f88c73bd4f5a82da8a35e699fba76e80c8b7 100644 (file)
--- a/drivers/gpu/drm/gma500/oaktrail_lvds.c
+++ b/drivers/gpu/drm/gma500/oaktrail_lvds.c
@@ -117,7 +117,7 @@ static void oaktrail_lvds_mode_set(struct drm_encoder *encoder,
                        break;
        }
 
-       if (!connector) {
+       if (list_entry_is_head(connector, &mode_config->connector_list, head)) {
                DRM_ERROR("Couldn't find connector when setting mode");
                gma_power_end(dev);
                return;