  Ins_SHZ( INS_ARG )
  {
    TT_GlyphZoneRec zp;
    FT_UShort       refp;
    FT_F26Dot6      dx,
                    dy;

    FT_UShort       last_point, i;


    if ( BOUNDS( args[0], 2 ) )
    {
      if ( CUR.pedantic_hinting )
        CUR.error = TT_Err_Invalid_Reference;
      return;
    }

    if ( COMPUTE_Point_Displacement( &dx, &dy, &zp, &refp ) )
      return;

    /* XXX: UNDOCUMENTED! SHZ doesn't move the phantom points.  */
    /*      Twilight zone has no contours, so use `n_points'.   */
    /*      Normal zone's `n_points' includes phantoms, so must */
    /*      use end of last contour.                            */
    if ( CUR.GS.gep2 == 0 && CUR.zp2.n_points > 0 )
      last_point = (FT_UShort)( CUR.zp2.n_points - 1 );
    else if ( CUR.GS.gep2 == 1 && CUR.zp2.n_contours > 0 )
      last_point = (FT_UShort)( CUR.zp2.contours[CUR.zp2.n_contours - 1] );
    else
      last_point = 0;

    /* XXX: UNDOCUMENTED! SHZ doesn't touch the points */
    for ( i = 0; i <= last_point; i++ )
    {
      if ( zp.cur != CUR.zp2.cur || refp != i )
        MOVE_Zp2_Point( i, dx, dy, FALSE );
    }
  }

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.