From c48aef0b653ba83452c97b1d1017869de2a846b9 Mon Sep 17 00:00:00 2001
From: "Yukihiro \"Matz\" Matsumoto" <matz@ruby-lang.org>
Date: Sat, 21 Jan 2017 17:59:49 +0900
Subject: Stack position may be bigger than stack bottom; fix #3401

This issue was reported by https://hackerone.com/titanous
---
 src/vm.c | 1 +
 1 file changed, 1 insertion(+)

(limited to 'src/vm.c')

diff --git a/src/vm.c b/src/vm.c
index c32fb0c0a..77372d937 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -137,6 +137,7 @@ stack_extend_alloc(mrb_state *mrb, int room, int keep)
   size_t size = mrb->c->stend - mrb->c->stbase;
   size_t off = mrb->c->stack - mrb->c->stbase;
 
+  if (off > size) size = off;
 #ifdef MRB_STACK_EXTEND_DOUBLING
   if (room <= size)
     size *= 2;
-- 
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