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From:   Cristian Marussi <cristian.marussi@arm.com>
To:     linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Cc:     sudeep.holla@arm.com, cristian.marussi@arm.com
Subject: [PATCH 3/6] firmware: arm_scmi: Harden accesses to Sensor domains
Date:   Wed, 17 Aug 2022 18:27:28 +0100
Message-Id: <20220817172731.1185305-4-cristian.marussi@arm.com>
In-Reply-To: <20220817172731.1185305-1-cristian.marussi@arm.com>
References: <20220817172731.1185305-1-cristian.marussi@arm.com>
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Accessing Sensor domains descriptors by index upon 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 in front of such domains descriptors
accesses.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
---
 drivers/firmware/arm_scmi/sensors.c | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/firmware/arm_scmi/sensors.c b/drivers/firmware/arm_scmi/sensors.c
index 7d0c7476d206..0b5853fa9d87 100644
--- a/drivers/firmware/arm_scmi/sensors.c
+++ b/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;
-- 
2.32.0