[PATCH v2] efi_loader: Extra checks while opening an OPTEE session

[Ilias Apalodimas]

Heinrich I found a slightly better way to do it and free teh session
on errors, so we dont have to check it.
I'll send a v3

Cheers
/Ilias


On Wed, 23 Dec 2020 at 13:25, Ilias Apalodimas
<ilias.apalodimas at linaro.org> wrote:
>
> When opening an OP-TEE session we need to check the internal return
> value of OP-TEE call arguments as well the return code of the
> function itself.
> The code was also ignoring to close the OP-TEE session in case the
> shared memory registration failed.
>
> Fixes: f042e47e8fb43 ("efi_loader: Implement EFI variable handling via OP-TEE")
> Signed-off-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
> ---
> changes since v1:
> - add a goto tag and use it on fails
>
>  lib/efi_loader/efi_variable_tee.c | 20 +++++++++++++++-----
>  1 file changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/lib/efi_loader/efi_variable_tee.c b/lib/efi_loader/efi_variable_tee.c
> index be6f3dfad469..b8808fdecad3 100644
> --- a/lib/efi_loader/efi_variable_tee.c
> +++ b/lib/efi_loader/efi_variable_tee.c
> @@ -36,20 +36,29 @@ static int get_connection(struct mm_connection *conn)
>         static const struct tee_optee_ta_uuid uuid = PTA_STMM_UUID;
>         struct udevice *tee = NULL;
>         struct tee_open_session_arg arg;
> -       int rc;
> +       int rc = -ENODEV;
>
>         tee = tee_find_device(tee, NULL, NULL, NULL);
>         if (!tee)
> -               return -ENODEV;
> +               goto out;
>
>         memset(&arg, 0, sizeof(arg));
>         tee_optee_ta_uuid_to_octets(arg.uuid, &uuid);
>         rc = tee_open_session(tee, &arg, 0, NULL);
> -       if (!rc) {
> -               conn->tee = tee;
> -               conn->session = arg.session;
> +       if (rc)
> +               goto out;
> +
> +       /* Check the internal OP-TEE result */
> +       if (arg.ret != TEE_SUCCESS) {
> +               rc = -EIO;
> +               goto out;
>         }
>
> +       conn->tee = tee;
> +       conn->session = arg.session;
> +
> +       return 0;
> +out:
>         return rc;
>  }
>
> @@ -88,6 +97,7 @@ static efi_status_t optee_mm_communicate(void *comm_buf, ulong dsize)
>
>         if (tee_shm_register(conn.tee, comm_buf, buf_size, 0, &shm)) {
>                 log_err("Unable to register shared memory\n");
> +               tee_close_session(conn.tee, conn.session);
>                 return EFI_UNSUPPORTED;
>         }
>
> --
> 2.30.0.rc1
>