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

[Ilias Apalodimas]

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.apalodi...@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