slimbus: ngd: validate logical address assigned by remote

Validate logical address assigned by remote, in failure cases this value
is all zeors.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/slimbus/qcom-ngd-ctrl.c

@@ -1004,6 +1004,7 @@ static int qcom_slim_ngd_get_laddr(struct slim_controller *ctrl,
 				   struct slim_eaddr *ea, u8 *laddr)
 {
 	struct slim_val_inf msg =  {0};
+	u8 failed_ea[6] = {0, 0, 0, 0, 0, 0};
 	struct slim_msg_txn txn;
 	u8 wbuf[10] = {0};
 	u8 rbuf[10] = {0};
@@ -1034,6 +1035,9 @@ static int qcom_slim_ngd_get_laddr(struct slim_controller *ctrl,
 		return ret;
 	}
 
+	if (!memcmp(rbuf, failed_ea, 6))
+		return -ENXIO;
+
 	*laddr = rbuf[6];
 
 	return ret;