lavc/utils: disallow zero sized packets with data set in avcodec_send_packet

Reviewed-by: wm4 <nfxjfg@googlemail.com>
Reviewed-by: Hendrik Leppkes <h.leppkes@gmail.com>
Signed-off-by: Marton Balint <cus@passwd.hu>

libavcodec/utils.c

@@ -2819,6 +2819,9 @@ int attribute_align_arg avcodec_send_packet(AVCodecContext *avctx, const AVPacke
     if (avctx->internal->draining)
         return AVERROR_EOF;
 
+    if (avpkt && !avpkt->size && avpkt->data)
+        return AVERROR(EINVAL);
+
     if (!avpkt || !avpkt->size) {
         avctx->internal->draining = 1;
         avpkt = NULL;