--- old/src/java.base/share/native/libzip/zip_util.c	2020-03-10 11:47:53.116764100 +0900
+++ new/src/java.base/share/native/libzip/zip_util.c	2020-03-10 11:47:52.245881700 +0900
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1995, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1995, 2020, 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
@@ -101,7 +101,7 @@
 ZFILE_Open(const char *fname, int flags) {
 #ifdef WIN32
     WCHAR *wfname, *wprefixed_fname;
-    size_t converted_chars, fname_length;
+    size_t fname_length;
     jlong fhandle;
     const DWORD access =
         (flags & O_RDWR)   ? (GENERIC_WRITE | GENERIC_READ) :
@@ -135,10 +135,17 @@
             flagsAndAttributes, /* flags and attributes */
             NULL);
     } else {
-        if ((wfname = (WCHAR*)malloc((fname_length + 1) * sizeof(WCHAR))) == NULL)
+        /* Get required buffer size to convert to Unicode */
+        int wfname_len = MultiByteToWideChar(CP_THREAD_ACP, MB_ERR_INVALID_CHARS,
+                                             fname, -1, NULL, 0);
+        if (wfname_len == 0) {
             return (jlong)INVALID_HANDLE_VALUE;
-
-        if (mbstowcs_s(&converted_chars, wfname, fname_length + 1, fname, fname_length) != 0) {
+        }
+        if ((wfname = (WCHAR*)malloc(wfname_len * sizeof(WCHAR))) == NULL) {
+            return (jlong)INVALID_HANDLE_VALUE;
+        }
+        if (MultiByteToWideChar(CP_THREAD_ACP, MB_ERR_INVALID_CHARS,
+                                fname, -1, wfname, wfname_len) == 0) {
             free(wfname);
             return (jlong)INVALID_HANDLE_VALUE;
         }