The file names in the upstream patch below were modified to apply to GNU
ghostscript.

From 0c0b0859ae1aba64861599f0e7f74f143f305932 Mon Sep 17 00:00:00 2001
From: Chris Liddell <chris.liddell@artifex.com>
Date: Tue, 7 Jul 2015 16:57:41 +0100
Subject: [PATCH] Bug 696041: sanity check for memory allocation.

In gs_heap_alloc_bytes(), add a sanity check to ensure we don't overflow the
variable holding the actual number of bytes we allocate.

No cluster differences
---
 gs/base/gsmalloc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/base/gsmalloc.c b/base/gsmalloc.c
index 624552d..cad79c2 100644
--- a/base/gsmalloc.c
+++ b/base/gsmalloc.c
@@ -178,7 +178,7 @@ gs_heap_alloc_bytes(gs_memory_t * mem, uint size, client_name_t cname)
     } else {
         uint added = size + sizeof(gs_malloc_block_t);
 
-        if (mmem->limit - added < mmem->used)
+        if (added <= size || mmem->limit - added < mmem->used)
             set_msg("exceeded limit");
         else if ((ptr = (byte *) Memento_label(malloc(added), cname)) == 0)
             set_msg("failed");
-- 
2.4.6

