--- a/src/share/vm/prims/jvm.cpp	Mon Aug 08 11:27:33 2016 -0700
+++ b/src/share/vm/prims/jvm.cpp	Tue Aug 16 08:59:54 2016 +0000
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -2868,7 +2868,18 @@
 int jio_vsnprintf(char *str, size_t count, const char *fmt, va_list args) {
   // see bug 4399518, 4417214
   if ((intptr_t)count <= 0) return -1;
-  return vsnprintf(str, count, fmt, args);
+
+  int result = vsnprintf(str, count, fmt, args);
+  // Note: on truncation vsnprintf(3) on Unix returns number of
+  // characters which would have been written had the buffer been large
+  // enough; on Windows, it returns -1. We handle both cases here and
+  // always return -1, and perform null termination.
+  if ((result > 0 && (size_t)result >= count) || result == -1) {
+    str[count - 1] = '\0';
+    result = -1;
+  }
+
+  return result;
 }
 
 ATTRIBUTE_PRINTF(3, 0)