diff -up lua-5.4.0/src/lgc.c.CVE-2020-15889 lua-5.4.0/src/lgc.c
--- lua-5.4.0/src/lgc.c.CVE-2020-15889	2020-07-31 09:52:45.494753815 -0400
+++ lua-5.4.0/src/lgc.c	2020-07-31 09:54:24.556428702 -0400
@@ -1131,16 +1131,14 @@ static void finishgencycle (lua_State *L
 
 
 /*
-** Does a young collection. First, mark 'OLD1' objects.  (Only survival
-** and "recent old" lists can contain 'OLD1' objects. New lists cannot
-** contain 'OLD1' objects, at most 'OLD0' objects that were already
-** visited when marked old.) Then does the atomic step. Then,
-** sweep all lists and advance pointers. Finally, finish the collection.
+** Does a young collection. First, mark 'OLD1' objects. Then does the
+** atomic step. Then sweep all lists and advance pointers. Finally,
+** finish the collection.
 */
 static void youngcollection (lua_State *L, global_State *g) {
   GCObject **psurvival;  /* to point to first non-dead survival object */
   lua_assert(g->gcstate == GCSpropagate);
-  markold(g, g->survival, g->reallyold);
+  markold(g, g->allgc, g->reallyold);
   markold(g, g->finobj, g->finobjrold);
   atomic(L);