gpgsm_sign (void *engine, gpgme_data_t in, gpgme_data_t out,
	    gpgme_sig_mode_t mode, int use_armor, int use_textmode,
	    int include_certs, gpgme_ctx_t ctx /* FIXME */)
{
  engine_gpgsm_t gpgsm = engine;
  gpgme_error_t err;
  char *assuan_cmd;
  int i;
  gpgme_key_t key;

  if (!gpgsm)
    return gpg_error (GPG_ERR_INV_VALUE);

  /* FIXME: This does not work as RESET does not reset it so we can't
     revert back to default.  */
  if (include_certs != GPGME_INCLUDE_CERTS_DEFAULT)
    {
      /* FIXME: Make sure that if we run multiple operations, that we
	 can reset any previously set value in case the default is
	 requested.  */

      if (asprintf (&assuan_cmd, "OPTION include-certs %i", include_certs) < 0)
	return gpg_error_from_syserror ();
      err = gpgsm_assuan_simple_command (gpgsm->assuan_ctx, assuan_cmd,
                                         NULL, NULL);
      free (assuan_cmd);
      if (err)
	return err;
    }

  for (i = 0; (key = gpgme_signers_enum (ctx, i)); i++)
    {
      const char *s = key->subkeys ? key->subkeys->fpr : NULL;
      if (s && strlen (s) < 80)
	{
          char buf[100];

          strcpy (stpcpy (buf, "SIGNER "), s);
          err = gpgsm_assuan_simple_command (gpgsm->assuan_ctx, buf,
                                             gpgsm->status.fnc,
                                             gpgsm->status.fnc_value);
	}
      else
        err = gpg_error (GPG_ERR_INV_VALUE);
      gpgme_key_unref (key);
      if (err)
        return err;
    }

  gpgsm->input_cb.data = in;
  err = gpgsm_set_fd (gpgsm, INPUT_FD, map_data_enc (gpgsm->input_cb.data));
  if (err)
    return err;
  gpgsm->output_cb.data = out;
  err = gpgsm_set_fd (gpgsm, OUTPUT_FD, use_armor ? "--armor"
		      : map_data_enc (gpgsm->output_cb.data));
  if (err)
    return err;
  gpgsm_clear_fd (gpgsm, MESSAGE_FD);
  gpgsm->inline_data = NULL;

  err = start (gpgsm, mode == GPGME_SIG_MODE_DETACH
	       ? "SIGN --detached" : "SIGN");
  return err;
}

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.