firmware: arm_scmi: Harden perf domain info access

Harden internal accesses to domain info in the SCMI perf protocol.
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20230717161246.1761777-2-cristian.marussi@arm.comSigned-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/firmware/arm_scmi/perf.c

@@ -139,7 +139,7 @@ struct perf_dom_info {
 
 struct scmi_perf_info {
 	u32 version;
-	int num_domains;
+	u16 num_domains;
 	enum scmi_power_scale power_scale;
 	u64 stats_addr;
 	u32 stats_size;
@@ -356,11 +356,26 @@ static int scmi_perf_mb_limits_set(const struct scmi_protocol_handle *ph,
 	return ret;
 }
 
+static inline struct perf_dom_info *
+scmi_perf_domain_lookup(const struct scmi_protocol_handle *ph, u32 domain)
+{
+	struct scmi_perf_info *pi = ph->get_priv(ph);
+
+	if (domain >= pi->num_domains)
+		return ERR_PTR(-EINVAL);
+
+	return pi->dom_info + domain;
+}
+
 static int scmi_perf_limits_set(const struct scmi_protocol_handle *ph,
 				u32 domain, u32 max_perf, u32 min_perf)
 {
 	struct scmi_perf_info *pi = ph->get_priv(ph);
-	struct perf_dom_info *dom = pi->dom_info + domain;
+	struct perf_dom_info *dom;
+
+	dom = scmi_perf_domain_lookup(ph, domain);
+	if (IS_ERR(dom))
+		return PTR_ERR(dom);
 
 	if (PROTOCOL_REV_MAJOR(pi->version) >= 0x3 && !max_perf && !min_perf)
 		return -EINVAL;
@@ -408,8 +423,11 @@ static int scmi_perf_mb_limits_get(const struct scmi_protocol_handle *ph,
 static int scmi_perf_limits_get(const struct scmi_protocol_handle *ph,
 				u32 domain, u32 *max_perf, u32 *min_perf)
 {
-	struct scmi_perf_info *pi = ph->get_priv(ph);
-	struct perf_dom_info *dom = pi->dom_info + domain;
+	struct perf_dom_info *dom;
+
+	dom = scmi_perf_domain_lookup(ph, domain);
+	if (IS_ERR(dom))
+		return PTR_ERR(dom);
 
 	if (dom->fc_info && dom->fc_info[PERF_FC_LIMIT].get_addr) {
 		struct scmi_fc_info *fci = &dom->fc_info[PERF_FC_LIMIT];
@@ -449,8 +467,11 @@ static int scmi_perf_mb_level_set(const struct scmi_protocol_handle *ph,
 static int scmi_perf_level_set(const struct scmi_protocol_handle *ph,
 			       u32 domain, u32 level, bool poll)
 {
-	struct scmi_perf_info *pi = ph->get_priv(ph);
-	struct perf_dom_info *dom = pi->dom_info + domain;
+	struct perf_dom_info *dom;
+
+	dom = scmi_perf_domain_lookup(ph, domain);
+	if (IS_ERR(dom))
+		return PTR_ERR(dom);
 
 	if (dom->fc_info && dom->fc_info[PERF_FC_LEVEL].set_addr) {
 		struct scmi_fc_info *fci = &dom->fc_info[PERF_FC_LEVEL];
@@ -490,8 +511,11 @@ static int scmi_perf_mb_level_get(const struct scmi_protocol_handle *ph,
 static int scmi_perf_level_get(const struct scmi_protocol_handle *ph,
 			       u32 domain, u32 *level, bool poll)
 {
-	struct scmi_perf_info *pi = ph->get_priv(ph);
-	struct perf_dom_info *dom = pi->dom_info + domain;
+	struct perf_dom_info *dom;
+
+	dom = scmi_perf_domain_lookup(ph, domain);
+	if (IS_ERR(dom))
+		return PTR_ERR(dom);
 
 	if (dom->fc_info && dom->fc_info[PERF_FC_LEVEL].get_addr) {
 		*level = ioread32(dom->fc_info[PERF_FC_LEVEL].get_addr);
@@ -574,13 +598,14 @@ static int scmi_dvfs_device_opps_add(const struct scmi_protocol_handle *ph,
 	unsigned long freq;
 	struct scmi_opp *opp;
 	struct perf_dom_info *dom;
-	struct scmi_perf_info *pi = ph->get_priv(ph);
 
 	domain = scmi_dev_domain_id(dev);
 	if (domain < 0)
-		return domain;
+		return -EINVAL;
 
-	dom = pi->dom_info + domain;
+	dom = scmi_perf_domain_lookup(ph, domain);
+	if (IS_ERR(dom))
+		return PTR_ERR(dom);
 
 	for (opp = dom->opp, idx = 0; idx < dom->opp_count; idx++, opp++) {
 		freq = opp->perf * dom->mult_factor;
@@ -603,14 +628,17 @@ static int
 scmi_dvfs_transition_latency_get(const struct scmi_protocol_handle *ph,
 				 struct device *dev)
 {
+	int domain;
 	struct perf_dom_info *dom;
-	struct scmi_perf_info *pi = ph->get_priv(ph);
-	int domain = scmi_dev_domain_id(dev);
 
+	domain = scmi_dev_domain_id(dev);
 	if (domain < 0)
-		return domain;
+		return -EINVAL;
+
+	dom = scmi_perf_domain_lookup(ph, domain);
+	if (IS_ERR(dom))
+		return PTR_ERR(dom);
 
-	dom = pi->dom_info + domain;
 	/* uS to nS */
 	return dom->opp[dom->opp_count - 1].trans_latency_us * 1000;
 }
@@ -618,8 +646,11 @@ scmi_dvfs_transition_latency_get(const struct scmi_protocol_handle *ph,
 static int scmi_dvfs_freq_set(const struct scmi_protocol_handle *ph, u32 domain,
 			      unsigned long freq, bool poll)
 {
-	struct scmi_perf_info *pi = ph->get_priv(ph);
-	struct perf_dom_info *dom = pi->dom_info + domain;
+	struct perf_dom_info *dom;
+
+	dom = scmi_perf_domain_lookup(ph, domain);
+	if (IS_ERR(dom))
+		return PTR_ERR(dom);
 
 	return scmi_perf_level_set(ph, domain, freq / dom->mult_factor, poll);
 }
@@ -630,11 +661,14 @@ static int scmi_dvfs_freq_get(const struct scmi_protocol_handle *ph, u32 domain,
 	int ret;
 	u32 level;
 	struct scmi_perf_info *pi = ph->get_priv(ph);
-	struct perf_dom_info *dom = pi->dom_info + domain;
 
 	ret = scmi_perf_level_get(ph, domain, &level, poll);
-	if (!ret)
+	if (!ret) {
+		struct perf_dom_info *dom = pi->dom_info + domain;
+
+		/* Note domain is validated implicitly by scmi_perf_level_get */
 		*freq = level * dom->mult_factor;
+	}
 
 	return ret;
 }
@@ -643,15 +677,14 @@ static int scmi_dvfs_est_power_get(const struct scmi_protocol_handle *ph,
 				   u32 domain, unsigned long *freq,
 				   unsigned long *power)
 {
-	struct scmi_perf_info *pi = ph->get_priv(ph);
 	struct perf_dom_info *dom;
 	unsigned long opp_freq;
 	int idx, ret = -EINVAL;
 	struct scmi_opp *opp;
 
-	dom = pi->dom_info + domain;
-	if (!dom)
-		return -EIO;
+	dom = scmi_perf_domain_lookup(ph, domain);
+	if (IS_ERR(dom))
+		return PTR_ERR(dom);
 
 	for (opp = dom->opp, idx = 0; idx < dom->opp_count; idx++, opp++) {
 		opp_freq = opp->perf * dom->mult_factor;
@@ -670,10 +703,16 @@ static int scmi_dvfs_est_power_get(const struct scmi_protocol_handle *ph,
 static bool scmi_fast_switch_possible(const struct scmi_protocol_handle *ph,
 				      struct device *dev)
 {
+	int domain;
 	struct perf_dom_info *dom;
-	struct scmi_perf_info *pi = ph->get_priv(ph);
 
-	dom = pi->dom_info + scmi_dev_domain_id(dev);
+	domain = scmi_dev_domain_id(dev);
+	if (domain < 0)
+		return false;
+
+	dom = scmi_perf_domain_lookup(ph, domain);
+	if (IS_ERR(dom))
+		return false;
 
 	return dom->fc_info && dom->fc_info[PERF_FC_LEVEL].set_addr;
 }