linux-kernel - [PATCH] cpufreq: apple-soc: Fix possible null-ptr-deref for cpufreq_cpu_get

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Message-ID: <20241230035714.72780-1-hanchunchao@inspur.com>
Date: Mon, 30 Dec 2024 11:57:14 +0800
From: Charles Han <hanchunchao@...pur.com>
To: <marcan@...can.st>, <sven@...npeter.dev>, <alyssa@...enzweig.io>,
	<rafael@...nel.org>, <viresh.kumar@...aro.org>, <maz@...nel.org>
CC: <asahi@...ts.linux.dev>, <linux-arm-kernel@...ts.infradead.org>,
	<linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Charles Han
	<hanchunchao@...pur.com>
Subject: [PATCH] cpufreq: apple-soc: Fix possible null-ptr-deref for cpufreq_cpu_get_raw()

cpufreq_cpu_get_raw() may return NULL if the cpu is not in
policy->cpus cpu mask and it will cause null pointer dereference.
But this returned value in apple_soc_cpufreq_get_rate() is not
checked. Add NULL check in apple_soc_cpufreq_get_rate(), to handle
kernel NULL pointer dereference error.

Fixes: 6286bbb40576 ("cpufreq: apple-soc: Add new driver to control Apple SoC CPU P-states")
Signed-off-by: Charles Han <hanchunchao@...pur.com>
---
 drivers/cpufreq/apple-soc-cpufreq.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/cpufreq/apple-soc-cpufreq.c b/drivers/cpufreq/apple-soc-cpufreq.c
index 4dcacab9b4bf..1c6d81355b41 100644
--- a/drivers/cpufreq/apple-soc-cpufreq.c
+++ b/drivers/cpufreq/apple-soc-cpufreq.c
@@ -104,6 +104,9 @@ static const struct of_device_id apple_soc_cpufreq_of_match[] __maybe_unused = {
 static unsigned int apple_soc_cpufreq_get_rate(unsigned int cpu)
 {
 	struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
+	if (unlikely(!policy))
+		return 0;
+
 	struct apple_cpu_priv *priv = policy->driver_data;
 	struct cpufreq_frequency_table *p;
 	unsigned int pstate;
-- 
2.31.1