coap: don't call memmove with empty source
@@ -1197,8 +1197,8 @@ coap_oscore_serialize_message(void *packet, uint8_t *buffer, bool inner,
if (coap_pkt->payload_len > 0) {
*option = 0xFF;
++option;
- }
memmove(option, coap_pkt->payload, coap_pkt->payload_len);
+ }
OC_DBG("Serialized payload:");
OC_LOGbytes(option, coap_pkt->payload_len);
} else {
