From 22a0cccb4d9d002f33c1ba7a4b36812c7d4f46b5 Mon Sep 17 00:00:00 2001
From: Werner Lemberg <wl@gnu.org>
Date: Sat, 19 Mar 2022 06:40:17 +0100
Subject: [PATCH] * src/base/ftobjs.c (ft_open_face_internal): Properly guard
 `face_index`.

We must ensure that the cast to `FT_Int` doesn't change the sign.

Fixes #1139.

Upstream-Status: Backport
https://gitlab.freedesktop.org/freetype/freetype/-/commit/22a0cccb4d9d002f33c1ba7a4b36812c7d4f46b5

Signed-off-by: Davide Gardenal <davide.gardenal@huawei.com>
---
 src/base/ftobjs.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/base/ftobjs.c b/src/base/ftobjs.c
index 2c0f0e6c9..10952a6c6 100644
--- a/src/base/ftobjs.c
+++ b/src/base/ftobjs.c
@@ -2527,6 +2527,15 @@
 #endif
 
 
+    /* only use lower 31 bits together with sign bit */
+    if ( face_index > 0 )
+      face_index &= 0x7FFFFFFFL;
+    else
+    {
+      face_index &= 0x7FFFFFFFL;
+      face_index  = -face_index;
+    }
+
 #ifdef FT_DEBUG_LEVEL_TRACE
     FT_TRACE3(( "FT_Open_Face: " ));
     if ( face_index < 0 )
-- 
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