Avoid the possibility to read out-of-bounds of a static global array in Vorbis

source/patched-ffmpeg/libavcodec/vorbis.c

 /**
  * @file
  * Common code for Vorbis I encoder and decoder
  * @author Denes Balatoni  ( dbalatoni programozo hu )
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
@@ skipping 132 matching lines @@
         for (j = i + 1; j < values; j++) {
             if (list[list[i].sort].x > list[list[j].sort].x) {
                 int tmp = list[i].sort;
                 list[i].sort = list[j].sort;
                 list[j].sort = tmp;
             }
         }
     }
 }
 
-static inline void render_line_unrolled(intptr_t x, intptr_t y, int x1,
+static inline void render_line_unrolled(intptr_t x, unsigned char y, int x1,
                                         intptr_t sy, int ady, int adx,
                                         float *buf)
 {
     int err = -adx;
     x -= x1 - 1;
     buf += x1 - 1;
     while (++x < 0) {
         err += ady;
         if (err >= 0) {
             err += ady - adx;
@@ skipping 14 matching lines @@
     int dy  = y1 - y0;
     int adx = x1 - x0;
     int ady = FFABS(dy);
     int sy  = dy < 0 ? -1 : 1;
     buf[x0] = ff_vorbis_floor1_inverse_db_table[y0];
     if (ady*2 <= adx) { // optimized common case
         render_line_unrolled(x0, y0, x1, sy, ady, adx, buf);
     } else {
         int base = dy / adx;
         int x    = x0;
-        int y    = y0;
+        unsigned char y = y0;
         int err  = -adx;
         ady -= FFABS(base) * adx;
         while (++x < x1) {
             y += base;
             err += ady;
             if (err >= 0) {
                 err -= adx;
                 y   += sy;
             }
             buf[x] = ff_vorbis_floor1_inverse_db_table[y];
@@ skipping 17 matching lines @@
                 render_line(lx, ly, FFMIN(x1,samples), y1, out);
             lx = x1;
             ly = y1;
         }
         if (lx >= samples)
             break;
     }
     if (lx < samples)
         render_line(lx, ly, samples, ly, out);
 }