[freetype2] master c3083e4: * src/base/ftobjs.c (ft_glyphslot_preset_bitmap): Fix integer

[Werner LEMBERG]

branch: master
commit c3083e459584d0e8481fa2401232c8a3145fae4b
Author: Werner Lemberg <address@hidden>
Commit: Werner Lemberg <address@hidden>

    * src/base/ftobjs.c (ft_glyphslot_preset_bitmap): Fix integer
    overflow.
    
    Reported as
    
      https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=3539
---
 ChangeLog         | 9 +++++++++
 src/base/ftobjs.c | 4 ++--
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 1890cbf..f131f2f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,14 @@
 2017-10-05  Werner Lemberg  <address@hidden>
 
+       * src/base/ftobjs.c (ft_glyphslot_preset_bitmap): Fix integer
+       overflow.
+
+       Reported as
+
+         https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=3539
+
+2017-10-05  Werner Lemberg  <address@hidden>
+
        Fix compiler warnings.
 
        * src/cff/cffdrivr.c (cff_ps_get_font_extra): Avoid code that relies
diff --git a/src/base/ftobjs.c b/src/base/ftobjs.c
index 79e7511..2258a31 100644
--- a/src/base/ftobjs.c
+++ b/src/base/ftobjs.c
@@ -419,8 +419,8 @@
       cbox.yMax = FT_PIX_CEIL( cbox.yMax );
     }
 
-    x_shift -= cbox.xMin;
-    y_shift -= cbox.yMin;
+    x_shift = SUB_LONG( x_shift, cbox.xMin );
+    y_shift = SUB_LONG( y_shift, cbox.yMin );
 
     x_left = cbox.xMin >> 6;
     y_top  = cbox.yMax >> 6;