[PATCH v1] cpufreq: scpi: Fix null-ptr-deref in scpi_cpufreq_get_rate()

[PATCH v1] cpufreq: scpi: Fix null-ptr-deref in scpi_cpufreq_get_rate()

[Henry Martin]

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@gmail.com>
---
 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..8f0da2a86e4b 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 (!policy)
+		return 0;
+
+	priv = policy->driver_data;
+	rate = clk_get_rate(priv->clk);
 
 	return rate / 1000;
 }
-- 
2.34.1

Re: [PATCH] cpufreq: scpi: Fix null-ptr-deref in scpi_cpufreq_get_rate()

[Markus Elfring]

> 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.

See also once more:
https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.15-rc1#n94


Can any other summary phrase variant become more desirable accordingly?

Regards,
Markus