[mbr] Fix null ptr use (#50173)

g_getenv can return NULL if the env var is unset

diff --git a/src/mono/mono/metadata/metadata-update.c b/src/mono/mono/metadata/metadata-update.c
index 3d1d78e..e5e91ce 100644 (file)
--- a/src/mono/mono/metadata/metadata-update.c
+++ b/src/mono/mono/metadata/metadata-update.c
@@ -85,7 +85,7 @@ mono_metadata_update_enabled (int *modifiable_assemblies_out)
 
        if (!inited) {
                char *val = g_getenv (DOTNET_MODIFIABLE_ASSEMBLIES);
-               if (!g_strcasecmp (val, "debug"))
+               if (val && !g_strcasecmp (val, "debug"))
                        modifiable = MONO_MODIFIABLE_ASSM_DEBUG;
                g_free (val);
                inited = TRUE;