From f6454c808075c76e194737e10adedf358394a609 Mon Sep 17 00:00:00 2001
From: Jeremy Evans <code@jeremyevans.net>
Date: Mon, 17 Apr 2017 12:12:40 -0700
Subject: [PATCH] Fix heap overflow by allocating more memory per heap page

REQUIRED_SIZE_BY_MALLOC needs to be added when using malloc,
otherwise ruby writes to unallocated memory.
---
 gc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gc.c b/gc.c
index ce80ccff7f..ddaddc9e86 100644
--- a/gc.c
+++ b/gc.c
@@ -1481,7 +1481,7 @@ heap_page_allocate(rb_objspace_t *objspace)
     int limit = HEAP_PAGE_OBJ_LIMIT;
 
     /* assign heap_page body (contains heap_page_header and RVALUEs) */
-    page_body = (struct heap_page_body *)aligned_malloc(HEAP_PAGE_ALIGN, HEAP_PAGE_SIZE);
+    page_body = (struct heap_page_body *)aligned_malloc(HEAP_PAGE_ALIGN, HEAP_PAGE_SIZE+REQUIRED_SIZE_BY_MALLOC);
     if (page_body == 0) {
 	rb_memerror();
     }
-- 
2.11.0