avcodec/speexdec: Check frames_per_packet more completely

Fixes: signed integer overflow: 2105344 * 539033345 cannot be represented in type 'int'
Fixes: out of array write
Fixes: 39956/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_SPEEX_fuzzer-4766419250708480
Fixes: 40293/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_SPEEX_fuzzer-5219910217760768

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/speexdec.c

@@ -1423,7 +1423,9 @@ static int parse_speex_extradata(AVCodecContext *avctx,
         return AVERROR_INVALIDDATA;
     s->vbr = bytestream_get_le32(&buf);
     s->frames_per_packet = bytestream_get_le32(&buf);
-    if (s->frames_per_packet <= 0)
+    if (s->frames_per_packet <= 0 ||
+        s->frames_per_packet > 64 ||
+        s->frames_per_packet >= INT32_MAX / s->nb_channels / s->frame_size)
         return AVERROR_INVALIDDATA;
     s->extra_headers = bytestream_get_le32(&buf);