[PATCH 5/5] usp10: Validate positioning record sequence indices in GPOS_apply_ContextPos().

[Aric Stewart]

Signed-off-by: Aric Stewart <aric at codeweavers.com>

On 4/17/17 1:27 PM, Henri Verbeet wrote:
> Signed-off-by: Henri Verbeet <hverbeet at codeweavers.com>
> ---
>  dlls/usp10/opentype.c | 19 ++++++++++++++-----
>  1 file changed, 14 insertions(+), 5 deletions(-)
> 
> diff --git a/dlls/usp10/opentype.c b/dlls/usp10/opentype.c
> index e190b92..d2e0fc5 100644
> --- a/dlls/usp10/opentype.c
> +++ b/dlls/usp10/opentype.c
> @@ -2195,12 +2195,21 @@ static unsigned int GPOS_apply_ContextPos(const ScriptCache *script_cache, const
>  
>                      for (l = 0; l < GET_BE_WORD(pr->PosCount); l++)
>                      {
> -                        int lookupIndex = GET_BE_WORD(pr_2->PosLookupRecord[l].LookupListIndex);
> -                        int SequenceIndex = GET_BE_WORD(pr_2->PosLookupRecord[l].SequenceIndex) * write_dir;
> +                        unsigned int lookup_index = GET_BE_WORD(pr_2->PosLookupRecord[l].LookupListIndex);
> +                        unsigned int sequence_index = GET_BE_WORD(pr_2->PosLookupRecord[l].SequenceIndex);
>  
> -                        TRACE("Position: %i -> %i %i\n",l, SequenceIndex, lookupIndex);
> -                        GPOS_apply_lookup(script_cache, otm, logfont, analysis, advance, lookup, lookupIndex,
> -                                glyphs, glyph_index + SequenceIndex, glyph_count, goffset);
> +                        g = glyph_index + write_dir * sequence_index;
> +                        if (g >= glyph_count)
> +                        {
> +                            WARN("Invalid sequence index %u (glyph index %u, write dir %d).\n",
> +                                    sequence_index, glyph_index, write_dir);
> +                            continue;
> +                        }
> +
> +                        TRACE("Position: %u -> %u %u.\n", l, sequence_index, lookup_index);
> +
> +                        GPOS_apply_lookup(script_cache, otm, logfont, analysis, advance,
> +                                lookup, lookup_index, glyphs, g, glyph_count, goffset);
>                      }
>                      return 1;
>                  }
>