[Git][freetype/freetype][master] [pfr] Fortify the kerning code.

[Alexei Podtelezhnikov (@apodtele)]

Alexei Podtelezhnikov pushed to branch master at FreeType / FreeType

Commits:

• 284956b5
  by Alexei Podtelezhnikov at 2022-07-26T12:23:15-04:00

  [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.
  

1 changed file:

• src/pfr/pfrobjs.c

Changes:

src/pfr/pfrobjs.c

---

...	...	@@ -486,17 +486,16 @@
486	486	kerning->x = 0;
487	487	kerning->y = 0;
488	488
489		- if ( glyph1 > 0 )
490		- glyph1--;
	489	+ /* PFR indexing skips .notdef, which becomes UINT_MAX */
	490	+ glyph1--;
	491	+ glyph2--;
491	492
492		- if ( glyph2 > 0 )
493		- glyph2--;
494		-
495		- /* convert glyph indices to character codes */
496		- if ( glyph1 > phy_font->num_chars ||
497		- glyph2 > phy_font->num_chars )
	493	+ /* check the array bounds, .notdef is automacally out */
	494	+ if ( glyph1 >= phy_font->num_chars ||
	495	+ glyph2 >= phy_font->num_chars )
498	496	goto Exit;
499	497
	498	+ /* convert glyph indices to character codes */
500	499	code1 = phy_font->chars[glyph1].char_code;
501	500	code2 = phy_font->chars[glyph2].char_code;
502	501	pair = PFR_KERN_INDEX( code1, code2 );

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