avcodec/opus_parser: Check payload_len in parse_opus_ts_header()

Fixes: clusterfuzz-testcase-minimized-6134545979277312
Fixes: crbug 797469

Reported-by: Matt Wolenetz <wolenetz@google.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 1bcd7fefcb)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/opus_parser.c

@@ -43,6 +43,7 @@ static const uint8_t *parse_opus_ts_header(const uint8_t *start, int *payload_le
     const uint8_t *buf = start + 1;
     int start_trim_flag, end_trim_flag, control_extension_flag, control_extension_length;
     uint8_t flags;
+    uint64_t payload_len_tmp;
 
     GetByteContext gb;
     bytestream2_init(&gb, buf, buf_len);
@@ -52,11 +53,11 @@ static const uint8_t *parse_opus_ts_header(const uint8_t *start, int *payload_le
     end_trim_flag          = (flags >> 3) & 1;
     control_extension_flag = (flags >> 2) & 1;
 
-    *payload_len = 0;
+    payload_len_tmp = *payload_len = 0;
     while (bytestream2_peek_byte(&gb) == 0xff)
-        *payload_len += bytestream2_get_byte(&gb);
+        payload_len_tmp += bytestream2_get_byte(&gb);
 
-    *payload_len += bytestream2_get_byte(&gb);
+    payload_len_tmp += bytestream2_get_byte(&gb);
 
     if (start_trim_flag)
         bytestream2_skip(&gb, 2);
@@ -67,6 +68,11 @@ static const uint8_t *parse_opus_ts_header(const uint8_t *start, int *payload_le
         bytestream2_skip(&gb, control_extension_length);
     }
 
+    if (bytestream2_tell(&gb) + payload_len_tmp > buf_len)
+        return NULL;
+
+    *payload_len = payload_len_tmp;
+
     return buf + bytestream2_tell(&gb);
 }
 
@@ -104,6 +110,10 @@ static int opus_find_frame_end(AVCodecParserContext *ctx, AVCodecContext *avctx,
             state = (state << 8) | payload[i];
             if ((state & OPUS_TS_MASK) == OPUS_TS_HEADER) {
                 payload = parse_opus_ts_header(payload, &payload_len, buf_size - i);
+                if (!payload) {
+                    av_log(avctx, AV_LOG_ERROR, "Error parsing Ogg TS header.\n");
+                    return AVERROR_INVALIDDATA;
+                }
                 *header_len = payload - buf;
                 start_found = 1;
                 break;