firmware: arm_scmi: Harden accesses to the sensor domains

Accessing sensor domains descriptors by the index upon the SCMI drivers
requests through the SCMI sensor operations interface can potentially
lead to out-of-bound violations if the SCMI driver misbehave.

Add an internal consistency check before any such domains descriptors
accesses.

Link: https://lore.kernel.org/r/20220817172731.1185305-4-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

Author: cris-ma

drivers/firmware/arm_scmi/sensors.c

@@ -762,6 +762,10 @@ static int scmi_sensor_config_get(const struct scmi_protocol_handle *ph,
 {
 	int ret;
 	struct scmi_xfer *t;
+	struct sensors_info *si = ph->get_priv(ph);
+
+	if (sensor_id >= si->num_sensors)
+		return -EINVAL;
 
 	ret = ph->xops->xfer_get_init(ph, SENSOR_CONFIG_GET,
 				      sizeof(__le32), sizeof(__le32), &t);
@@ -771,7 +775,6 @@ static int scmi_sensor_config_get(const struct scmi_protocol_handle *ph,
 	put_unaligned_le32(sensor_id, t->tx.buf);
 	ret = ph->xops->do_xfer(ph, t);
 	if (!ret) {
-		struct sensors_info *si = ph->get_priv(ph);
 		struct scmi_sensor_info *s = si->sensors + sensor_id;
 
 		*sensor_config = get_unaligned_le64(t->rx.buf);
@@ -788,6 +791,10 @@ static int scmi_sensor_config_set(const struct scmi_protocol_handle *ph,
 	int ret;
 	struct scmi_xfer *t;
 	struct scmi_msg_sensor_config_set *msg;
+	struct sensors_info *si = ph->get_priv(ph);
+
+	if (sensor_id >= si->num_sensors)
+		return -EINVAL;
 
 	ret = ph->xops->xfer_get_init(ph, SENSOR_CONFIG_SET,
 				      sizeof(*msg), 0, &t);
@@ -800,7 +807,6 @@ static int scmi_sensor_config_set(const struct scmi_protocol_handle *ph,
 
 	ret = ph->xops->do_xfer(ph, t);
 	if (!ret) {
-		struct sensors_info *si = ph->get_priv(ph);
 		struct scmi_sensor_info *s = si->sensors + sensor_id;
 
 		s->sensor_config = sensor_config;
@@ -831,8 +837,11 @@ static int scmi_sensor_reading_get(const struct scmi_protocol_handle *ph,
 	int ret;
 	struct scmi_xfer *t;
 	struct scmi_msg_sensor_reading_get *sensor;
+	struct scmi_sensor_info *s;
 	struct sensors_info *si = ph->get_priv(ph);
-	struct scmi_sensor_info *s = si->sensors + sensor_id;
+
+	if (sensor_id >= si->num_sensors)
+		return -EINVAL;
 
 	ret = ph->xops->xfer_get_init(ph, SENSOR_READING_GET,
 				      sizeof(*sensor), 0, &t);
@@ -841,6 +850,7 @@ static int scmi_sensor_reading_get(const struct scmi_protocol_handle *ph,
 
 	sensor = t->tx.buf;
 	sensor->id = cpu_to_le32(sensor_id);
+	s = si->sensors + sensor_id;
 	if (s->async) {
 		sensor->flags = cpu_to_le32(SENSOR_READ_ASYNC);
 		ret = ph->xops->do_xfer_with_response(ph, t);
@@ -895,9 +905,13 @@ scmi_sensor_reading_get_timestamped(const struct scmi_protocol_handle *ph,
 	int ret;
 	struct scmi_xfer *t;
 	struct scmi_msg_sensor_reading_get *sensor;
+	struct scmi_sensor_info *s;
 	struct sensors_info *si = ph->get_priv(ph);
-	struct scmi_sensor_info *s = si->sensors + sensor_id;
 
+	if (sensor_id >= si->num_sensors)
+		return -EINVAL;
+
+	s = si->sensors + sensor_id;
 	if (!count || !readings ||
 	    (!s->num_axis && count > 1) || (s->num_axis && count > s->num_axis))
 		return -EINVAL;