initialize conf to NULL

upgrade.c

# git diff upgrade.c
diff --git a/pkg/upgrade.c b/pkg/upgrade.c
index 664db04..3968ffb 100644
--- a/pkg/upgrade.c
+++ b/pkg/upgrade.c
@@ -33,7 +33,7 @@ exec_upgrade(int argc, char **argv)
        int64_t oldsize = 0, newsize = 0;
        int64_t dlsize = 0;
        char size[7];
-       properties conf;
+       properties conf = NULL;
 
        (void) argv;
        if (argc != 1) {