vqavideo: check chunk sizes before reading chunks

Fixes out of array writes

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit ab6c9332)
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit 13093f97)

CC: libav-stable@libav.org
Signed-off-by: Reinhard Tartler <siretart@tauware.de>

libavcodec/vqavideo.c

@@ -532,6 +532,12 @@ static int vqa_decode_chunk(VqaContext *s)
         bytestream2_seek(&s->gb, cbp0_chunk, SEEK_SET);
         chunk_size = bytestream2_get_be32(&s->gb);
 
+        if (chunk_size > MAX_CODEBOOK_SIZE - s->next_codebook_buffer_index) {
+            av_log(s->avctx, AV_LOG_ERROR, "cbp0 chunk too large (%u bytes)\n",
+                   chunk_size);
+            return AVERROR_INVALIDDATA;
+        }
+
         /* accumulate partial codebook */
         bytestream2_get_buffer(&s->gb, &s->next_codebook_buffer[s->next_codebook_buffer_index],
                                chunk_size);
@@ -555,6 +561,12 @@ static int vqa_decode_chunk(VqaContext *s)
         bytestream2_seek(&s->gb, cbpz_chunk, SEEK_SET);
         chunk_size = bytestream2_get_be32(&s->gb);
 
+        if (chunk_size > MAX_CODEBOOK_SIZE - s->next_codebook_buffer_index) {
+            av_log(s->avctx, AV_LOG_ERROR, "cbpz chunk too large (%u bytes)\n",
+                   chunk_size);
+            return AVERROR_INVALIDDATA;
+        }
+
         /* accumulate partial codebook */
         bytestream2_get_buffer(&s->gb, &s->next_codebook_buffer[s->next_codebook_buffer_index],
                                chunk_size);