diff -rauN jdk10u-jdk-10.0.2+13/src/hotspot/share/utilities/bitMap.cpp jdk10u-jdk-10.0.2+13-bitmap-segv-patch/src/hotspot/share/utilities/bitMap.cpp
--- jdk10u-jdk-10.0.2+13/src/hotspot/share/utilities/bitMap.cpp	2018-06-24 16:07:06.000000000 +0200
+++ jdk10u-jdk-10.0.2+13-bitmap-segv-patch/src/hotspot/share/utilities/bitMap.cpp	2021-05-17 17:10:22.467980460 +0200
@@ -548,7 +548,9 @@
   bm_word_t* dest_map = map();
   const bm_word_t* other_map = other.map();
   idx_t copy_words = word_index(size());
-  Copy::disjoint_words((HeapWord*)other_map, (HeapWord*)dest_map, copy_words);
+  if (other_map != NULL) {
+    Copy::disjoint_words((HeapWord*)other_map, (HeapWord*)dest_map, copy_words);
+  }
   idx_t rest = bit_in_word(size());
   if (rest > 0) {
     dest_map[copy_words] = merge_tail_of_map(other_map[copy_words],