vorbisdec: Fix decoding bug with channel handling

Fixes Bug: #191
Chromium Bug: #101458
CVE-2011-3895

Signed-off-by: Reinhard Tartler <siretart@tauware.de>
(cherry picked from commit e6d527ff72)

Signed-off-by: Reinhard Tartler <siretart@tauware.de>
(cherry picked from commit 97f23c72a3)

Conflicts:

	libavcodec/vorbis_dec.c

libavcodec/vorbis_dec.c

@@ -656,7 +656,7 @@ static int vorbis_parse_setup_hdr_residues(vorbis_context *vc)
         res_setup->partition_size = get_bits(gb, 24) + 1;
         /* Validations to prevent a buffer overflow later. */
         if (res_setup->begin>res_setup->end ||
-            res_setup->end>vc->blocksize[1] / (res_setup->type == 2 ? 1 : 2) ||
+            res_setup->end > (res_setup->type == 2 ? vc->avccontext->channels : 1) * vc->blocksize[1] / 2 ||
             (res_setup->end-res_setup->begin) / res_setup->partition_size > V_MAX_PARTITIONS) {
             av_log(vc->avccontext, AV_LOG_ERROR, "partition out of bounds: type, begin, end, size, blocksize: %"PRIdFAST16", %"PRIdFAST32", %"PRIdFAST32", %"PRIdFAST32", %"PRIdFAST32"\n", res_setup->type, res_setup->begin, res_setup->end, res_setup->partition_size, vc->blocksize[1] / 2);
             return -1;
@@ -1473,6 +1473,7 @@ static int vorbis_parse_audio_packet(vorbis_context *vc)
     uint_fast8_t res_num = 0;
     int_fast16_t retlen  = 0;
     float fadd_bias = vc->add_bias;
+    int ch_left = vc->audio_channels;
 
     if (get_bits1(gb)) {
         av_log(vc->avccontext, AV_LOG_ERROR, "Not a Vorbis I audio packet.\n");
@@ -1546,9 +1547,14 @@ static int vorbis_parse_audio_packet(vorbis_context *vc)
             }
         }
         residue = &vc->residues[mapping->submap_residue[i]];
+        if (ch_left < ch) {
+            av_log(vc->avccontext, AV_LOG_ERROR, "Too many channels in vorbis_floor_decode.\n");
+            return -1;
+        }
         vorbis_residue_decode(vc, residue, ch, do_not_decode, ch_res_ptr, blocksize/2);
 
         ch_res_ptr += ch * blocksize / 2;
+        ch_left -= ch;
     }
 
 // Inverse coupling