commit c484d8904285652246c3af212a4211b9a8955149
Author: Thomas Stuefe <stuefe@openjdk.org>
Date:   Tue Mar 16 05:49:01 2021 +0000

    8263557: Possible NULL dereference in Arena::destruct_contents()
    
    Reviewed-by: kbarrett, coleenp

diff --git src/hotspot/share/memory/arena.cpp src/hotspot/share/memory/arena.cpp
index 8388f68c359..16059bed9be 100644
--- src/hotspot/share/memory/arena.cpp
+++ src/hotspot/share/memory/arena.cpp
@@ -310,7 +310,9 @@ void Arena::destruct_contents() {
   // reset size before chop to avoid a rare racing condition
   // that can have total arena memory exceed total chunk memory
   set_size_in_bytes(0);
-  _first->chop();
+  if (_first != NULL) {
+    _first->chop();
+  }
   reset();
 }