From aaf490d794bd077330c306face305f4a87de5809 Mon Sep 17 00:00:00 2001
From: "Devin J. Pohly" <djpohly@gmail.com>
Date: Thu, 30 Jul 2020 23:23:18 -0500
Subject: [PATCH] drm: fix uninitialized read

get_drm_prop_blob does not set path_len if it returns NULL.  Check the
return value before path_len to avoid reading uninitialized memory.

(Granted, this doesn't change the logic at all, but it does make
Valgrind a bit happier.)
---
 backend/drm/drm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/backend/drm/drm.c b/backend/drm/drm.c
index 7ecc28d3..dafe807b 100644
--- a/backend/drm/drm.c
+++ b/backend/drm/drm.c
@@ -1398,7 +1398,7 @@ void scan_drm_connectors(struct wlr_drm_backend *drm) {
 			bool is_mst = false;
 			char *path = get_drm_prop_blob(drm->fd, wlr_conn->id,
 				wlr_conn->props.path, &path_len);
-			if (path_len > 4 && path && strncmp(path, "mst:", 4) == 0) {
+			if (path && path_len > 4 && strncmp(path, "mst:", 4) == 0) {
 				is_mst = true;
 			}
 			free(path);