Commit 53dfdcd8198d2b3201a23c4bad9190519ba918db
2022-03-17T19:24:16
[sfnt] Avoid invalid face index. Fixes #1138. * src/sfnt/sfobjs.c (sfnt_init_face), src/sfnt/sfwoff2.c (woff2_open_font): Check `face_index` before decrementing.
diff --git a/src/sfnt/sfobjs.c b/src/sfnt/sfobjs.c
index f9d4d38..9771c35 100644
--- a/src/sfnt/sfobjs.c
+++ b/src/sfnt/sfobjs.c
@@ -566,7 +566,7 @@
face_index = FT_ABS( face_instance_index ) & 0xFFFF;
/* value -(N+1) requests information on index N */
- if ( face_instance_index < 0 )
+ if ( face_instance_index < 0 && face_index > 0 )
face_index--;
if ( face_index >= face->ttc_header.count )
diff --git a/src/sfnt/sfwoff2.c b/src/sfnt/sfwoff2.c
index cb1e066..165b875 100644
--- a/src/sfnt/sfwoff2.c
+++ b/src/sfnt/sfwoff2.c
@@ -2085,7 +2085,7 @@
/* Validate requested face index. */
*num_faces = woff2.num_fonts;
/* value -(N+1) requests information on index N */
- if ( *face_instance_index < 0 )
+ if ( *face_instance_index < 0 && face_index > 0 )
face_index--;
if ( face_index >= woff2.num_fonts )