h265_parse: skip zero sized NAL units

Avoids extra error checks later on and/or invalid reads.
Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>

libavcodec/h2645_parse.c

@@ -333,7 +333,7 @@ int ff_h2645_packet_split(H2645Packet *pkt, const uint8_t *buf, int length,
             ret = hevc_parse_nal_header(nal, logctx);
         else
             ret = h264_parse_nal_header(nal, logctx);
-        if (ret <= 0) {
+        if (ret <= 0 || nal->size <= 0) {
             if (ret < 0) {
                 av_log(logctx, AV_LOG_ERROR, "Invalid NAL unit %d, skipping.\n",
                        nal->type);