From 4d0adf6d5f02b1b8c6745031f2a502f84fe85d43 Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Tue, 10 Oct 2017 09:41:17 +0900
Subject: [PATCH] Fix out-of-bound access

Fix up 1f2b3380f51a19cc6f5d577d4ac6c0a226ba1911
---
 ext/mkfifo.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/ext/mkfifo.c b/ext/mkfifo.c
index dbc49c1..c455547 100644
--- a/ext/mkfifo.c
+++ b/ext/mkfifo.c
@@ -26,9 +26,9 @@ rb_cFile_mkfifo(int argc, VALUE *argv, VALUE self) {
     mode_t perm = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP;
 
 #ifdef rb_check_arity
-    rb_check_arity(argc, 1, 2);
+    argc = rb_check_arity(argc, 1, 2);
     name = argv[0];
-    mode = argv[1];
+    mode = argc > 1 ? argv[1] : Qnil;
 #else
     rb_scan_args(argc, argv, "11", &name, &mode);
 #endif