[PATCH 2/2] tee: optee: don't enumerate services if there ain't any

[Jens Wiklander]

On Wed, Nov 29, 2023 at 1:37 PM Etienne Carriere
<etienne.carriere at foss.st.com> wrote:
>
> Change optee driver service enumeration to not enumerate (and
> allocate a zero sized shared memory buffer) when OP-TEE
> reports that there is no service to enumerate.
>
> This change fixes an existing issue that occurs when the such zero
> sized shared memory buffer allocated from malloc() has a physical
> address of offset 0 of a physical 4kB page. In such case, OP-TEE
> secure world refuses to register the zero-sized shared memory
> area and makes U-Boot optee service enumeration to fail.
>
> Fixes: 94ccfb78a4d6 ("drivers: tee: optee: discover OP-TEE services")
> Signed-off-by: Etienne Carriere <etienne.carriere at foss.st.com>
> ---
>  drivers/tee/optee/core.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)

Reviewed-by: Jens Wiklander <jens.wiklander at linaro.org>

Thanks,
Jens

>
> diff --git a/drivers/tee/optee/core.c b/drivers/tee/optee/core.c
> index 5308dd58ce..47f845cffe 100644
> --- a/drivers/tee/optee/core.c
> +++ b/drivers/tee/optee/core.c
> @@ -139,6 +139,11 @@ static int enum_services(struct udevice *dev, struct tee_shm **shm, size_t *coun
>         if (ret)
>                 return ret;
>
> +       if (!shm_size) {
> +               *count = 0;
> +               return 0;
> +       }
> +
>         ret = tee_shm_alloc(dev, shm_size, 0, shm);
>         if (ret) {
>                 dev_err(dev, "Failed to allocated shared memory: %d\n", ret);
> @@ -185,14 +190,15 @@ static int bind_service_drivers(struct udevice *dev)
>
>         ret = enum_services(dev, &service_list, &service_count, tee_sess,
>                             PTA_CMD_GET_DEVICES);
> -       if (!ret)
> +       if (!ret && service_count)
>                 ret = bind_service_list(dev, service_list, service_count);
>
>         tee_shm_free(service_list);
> +       service_list = NULL;
>
>         ret2 = enum_services(dev, &service_list, &service_count, tee_sess,
>                              PTA_CMD_GET_DEVICES_SUPP);
> -       if (!ret2)
> +       if (!ret2 && service_count)
>                 ret2 = bind_service_list(dev, service_list, service_count);
>
>         tee_shm_free(service_list);
> --
> 2.25.1
>