From 719f700adf7598d0ad910dcd3a94aad2ef354033 Mon Sep 17 00:00:00 2001
From: "Yukihiro \"Matz\" Matsumoto" <matz@ruby-lang.org>
Date: Tue, 14 Feb 2017 00:15:58 +0900
Subject: Extend mruby stack when keep is bigger than room; fix #3421

But #3421 still cause stack overflow error due to infinite recursion.
To prevent overflow, we need to add different stack depth check.
---
 src/vm.c | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'src/vm.c')

diff --git a/src/vm.c b/src/vm.c
index b89b6d0c5..8bb446fa9 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -169,6 +169,9 @@ stack_extend_alloc(mrb_state *mrb, int room, int keep)
 static inline void
 stack_extend(mrb_state *mrb, int room, int keep)
 {
+  if (room < keep) {
+    room = keep;
+  }
   if (mrb->c->stack + room >= mrb->c->stend) {
     stack_extend_alloc(mrb, room, keep);
   }
-- 
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