[freetype2] master 839cb40: * src/truetype/ttgxvar.c (tt_set_mm_blend): Fix off-by-one error.

[Werner LEMBERG]

branch: master
commit 839cb404cf73f4410d58ebb3a99d16e08f4bdee7
Author: Werner Lemberg <address@hidden>
Commit: Werner Lemberg <address@hidden>

    * src/truetype/ttgxvar.c (tt_set_mm_blend): Fix off-by-one error.
    
    Reported as
    
      https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=9412
---
 ChangeLog              | 8 ++++++++
 src/truetype/ttgxvar.c | 7 +++++--
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 87f3d17..9ce6368 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2018-07-16  Werner Lemberg  <address@hidden>
+
+       * src/truetype/ttgxvar.c (tt_set_mm_blend): Fix off-by-one error.
+
+       Reported as
+
+         https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=9412
+
 2018-07-12  Werner Lemberg  <address@hidden>
 
        * src/base/ftoutln.c (FT_Outline_Get_Orientation): Init `cbox'.
diff --git a/src/truetype/ttgxvar.c b/src/truetype/ttgxvar.c
index 0937301..d143fce 100644
--- a/src/truetype/ttgxvar.c
+++ b/src/truetype/ttgxvar.c
@@ -2533,11 +2533,14 @@
 
       if ( FT_IS_NAMED_INSTANCE( FT_FACE( face ) ) )
       {
-        FT_UInt  idx = (FT_UInt)face->root.face_index >> 16;
+        FT_UInt  instance_index = (FT_UInt)face->root.face_index >> 16;
 
 
         c = blend->normalizedcoords + i;
-        n = blend->normalized_stylecoords + idx * mmvar->num_axis + i;
+        n = blend->normalized_stylecoords            +
+            ( instance_index - 1 ) * mmvar->num_axis +
+            i;
+
         for ( j = i; j < mmvar->num_axis; j++, n++, c++ )
           if ( *c != *n )
             have_diff = 1;