Subject: Backport of JDK-8333149 ubsan : memset on nullptr target detected in jvmtiEnvBase.cpp get_object_monitor_usage

---
 src/hotspot/share/prims/jvmtiEnvBase.cpp | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/hotspot/share/prims/jvmtiEnvBase.cpp b/src/hotspot/share/prims/jvmtiEnvBase.cpp
index 7c67a0eeb..d4b924b78 100644
--- a/src/hotspot/share/prims/jvmtiEnvBase.cpp
+++ b/src/hotspot/share/prims/jvmtiEnvBase.cpp
@@ -1515,8 +1515,12 @@ JvmtiEnvBase::get_object_monitor_usage(JavaThread* calling_thread, jobject objec
 
     // Number of waiters may actually be less than the waiter count.
     // So null out memory so that unused memory will be null.
-    memset(ret.waiters, 0, ret.waiter_count * sizeof(jthread *));
-    memset(ret.notify_waiters, 0, ret.notify_waiter_count * sizeof(jthread *));
+    if (ret.waiters != nullptr) {
+      memset(ret.waiters, 0, ret.waiter_count * sizeof(jthread *));
+    }
+    if (ret.notify_waiters != nullptr) {
+      memset(ret.notify_waiters, 0, ret.notify_waiter_count * sizeof(jthread *));
+    }
 
     if (ret.waiter_count > 0) {
       // we have contending and/or waiting threads
-- 
2.33.0