--- old/src/hotspot/share/prims/jvm.cpp	2018-05-01 09:30:57.523120776 +0900
+++ new/src/hotspot/share/prims/jvm.cpp	2018-05-01 09:30:57.359120165 +0900
@@ -2719,10 +2719,10 @@
 int jio_vsnprintf(char *str, size_t count, const char *fmt, va_list args) {
   // Reject count values that are negative signed values converted to
   // unsigned; see bug 4399518, 4417214
-  if ((intptr_t)count <= 0) return -1;
+  if ((intptr_t)count < 0) return -1;
 
   int result = os::vsnprintf(str, count, fmt, args);
-  if (result > 0 && (size_t)result >= count) {
+  if (count > 0 && result > 0 && (size_t)result >= count) {
     result = -1;
   }