firmware: qcom: uefisecapp: fix efivars registration race

Since the conversion to using the TZ allocator, the efivars service is
registered before the memory pool has been allocated, something which
can lead to a NULL-pointer dereference in case of a racing EFI variable
access.

Make sure that all resources have been set up before registering the
efivars.

Fixes: 6612103 ("firmware: qcom: qseecom: convert to using the TZ allocator")
Cc: stable@vger.kernel.org	# 6.11
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Reviewed-by: Maximilian Luz <luzmaximilian@gmail.com>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Link: https://lore.kernel.org/r/20250120151000.13870-1-johan+linaro@kernel.org
Signed-off-by: Bjorn Andersson <andersson@kernel.org>

drivers/firmware/qcom/qcom_qseecom_uefisecapp.c

@@ -814,15 +814,6 @@ static int qcom_uefisecapp_probe(struct auxiliary_device *aux_dev,
 
 	qcuefi->client = container_of(aux_dev, struct qseecom_client, aux_dev);
 
-	auxiliary_set_drvdata(aux_dev, qcuefi);
-	status = qcuefi_set_reference(qcuefi);
-	if (status)
-		return status;
-
-	status = efivars_register(&qcuefi->efivars, &qcom_efivar_ops);
-	if (status)
-		qcuefi_set_reference(NULL);
-
 	memset(&pool_config, 0, sizeof(pool_config));
 	pool_config.initial_size = SZ_4K;
 	pool_config.policy = QCOM_TZMEM_POLICY_MULTIPLIER;
@@ -833,6 +824,15 @@ static int qcom_uefisecapp_probe(struct auxiliary_device *aux_dev,
 	if (IS_ERR(qcuefi->mempool))
 		return PTR_ERR(qcuefi->mempool);
 
+	auxiliary_set_drvdata(aux_dev, qcuefi);
+	status = qcuefi_set_reference(qcuefi);
+	if (status)
+		return status;
+
+	status = efivars_register(&qcuefi->efivars, &qcom_efivar_ops);
+	if (status)
+		qcuefi_set_reference(NULL);
+
 	return status;
 }