static CURLcode smtp_perform_upgrade_tls(struct connectdata *conn)
{
  CURLcode result = CURLE_OK;
  struct smtp_conn *smtpc = &conn->proto.smtpc;

  /* Start the SSL connection */
  result = Curl_ssl_connect_nonblocking(conn, FIRSTSOCKET, &smtpc->ssldone);

  if(!result) {
    if(smtpc->state != SMTP_UPGRADETLS)
      state(conn, SMTP_UPGRADETLS);

    if(smtpc->ssldone) {
      smtp_to_smtps(conn);
      result = smtp_perform_ehlo(conn);
    }
  }

  return result;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.