Commit 284956b5b123125c814bb3841c6871ddfb0694a3
2022-07-26T12:23:15
[pfr] Fortify the kerning code. Any array index must be strictly less then the array size. Therefore, we must reject indexes that are equal to the array size. Alternatively, we should move the bounds check before the index decrement but that would be confusing. In addition, it is ok to decrement zero (.notdef) and get UINT_MAX, which is then automatically rejected in the bounds check. * src/pfr/pfrobjs.c (pfr_face_get_kerning): Fix the bounds checking.
diff --git a/src/pfr/pfrobjs.c b/src/pfr/pfrobjs.c
index 8b29fc0..1457adc 100644
--- a/src/pfr/pfrobjs.c
+++ b/src/pfr/pfrobjs.c
@@ -486,17 +486,16 @@
kerning->x = 0;
kerning->y = 0;
- if ( glyph1 > 0 )
- glyph1--;
+ /* PFR indexing skips .notdef, which becomes UINT_MAX */
+ glyph1--;
+ glyph2--;
- if ( glyph2 > 0 )
- glyph2--;
-
- /* convert glyph indices to character codes */
- if ( glyph1 > phy_font->num_chars ||
- glyph2 > phy_font->num_chars )
+ /* check the array bounds, .notdef is automacally out */
+ if ( glyph1 >= phy_font->num_chars ||
+ glyph2 >= phy_font->num_chars )
goto Exit;
+ /* convert glyph indices to character codes */
code1 = phy_font->chars[glyph1].char_code;
code2 = phy_font->chars[glyph2].char_code;
pair = PFR_KERN_INDEX( code1, code2 );