linux-kernel - [PATCH v2 2/2] cpufreq: scpi: Fix null-ptr-deref in scpi_cpufreq_get

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Message-Id: <20250408150354.104532-3-bsdhenrymartin@gmail.com>
Date: Tue,  8 Apr 2025 23:03:54 +0800
From: Henry Martin <bsdhenrymartin@...il.com>
To: sudeep.holla@....com,
	cristian.marussi@....com,
	rafael@...nel.org,
	viresh.kumar@...aro.org
Cc: arm-scmi@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Henry Martin <bsdhenrymartin@...il.com>
Subject: [PATCH v2 2/2] cpufreq: scpi: Fix null-ptr-deref in scpi_cpufreq_get_rate()

cpufreq_cpu_get_raw() can return NULL when the target CPU is not present
in the policy->cpus mask. scpi_cpufreq_get_rate() does not check for
this case, which results in a NULL pointer dereference.

Fixes: 343a8d17fa8d ("cpufreq: scpi: remove arm_big_little dependency")
Signed-off-by: Henry Martin <bsdhenrymartin@...il.com>
---
V1 -> V2: Use `if (unlikely(!policy))` instead of `if (!policy)`

 drivers/cpufreq/scpi-cpufreq.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/cpufreq/scpi-cpufreq.c b/drivers/cpufreq/scpi-cpufreq.c
index 17cda84f00df..dcbb0ae7dd47 100644
--- a/drivers/cpufreq/scpi-cpufreq.c
+++ b/drivers/cpufreq/scpi-cpufreq.c
@@ -29,9 +29,16 @@ static struct scpi_ops *scpi_ops;
 
 static unsigned int scpi_cpufreq_get_rate(unsigned int cpu)
 {
-	struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
-	struct scpi_data *priv = policy->driver_data;
-	unsigned long rate = clk_get_rate(priv->clk);
+	struct cpufreq_policy *policy;
+	struct scpi_data *priv;
+	unsigned long rate;
+
+	policy = cpufreq_cpu_get_raw(cpu);
+	if (unlikely(!policy))
+		return 0;
+
+	priv = policy->driver_data;
+	rate = clk_get_rate(priv->clk);
 
 	return rate / 1000;
 }
-- 
2.34.1