linux-kernel - [PATCH] cpufreq: apple-soc: Fix possible null pointer dereference

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Message-Id: <20250412160518.1824538-1-chenyuan0y@gmail.com>
Date: Sat, 12 Apr 2025 11:05:18 -0500
From: Chenyuan Yang <chenyuan0y@...il.com>
To: sven@...npeter.dev,
	j@...nau.net,
	alyssa@...enzweig.io,
	neal@...pa.dev,
	rafael@...nel.org,
	viresh.kumar@...aro.org,
	marcan@...can.st,
	maz@...nel.org
Cc: asahi@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org,
	linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Chenyuan Yang <chenyuan0y@...il.com>
Subject: [PATCH] cpufreq: apple-soc: Fix possible null pointer dereference

Check if policy is NULL before dereferencing it.

This is similar to the commit cf7de25878a1
("cppc_cpufreq: Fix possible null pointer dereference").

This is found by our static analysis tool KNighter.

Signed-off-by: Chenyuan Yang <chenyuan0y@...il.com>
Fixes: 6286bbb40576 ("cpufreq: apple-soc: Add new driver to control Apple SoC CPU P-states")
---
 drivers/cpufreq/apple-soc-cpufreq.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/cpufreq/apple-soc-cpufreq.c b/drivers/cpufreq/apple-soc-cpufreq.c
index 4994c86feb57..3de9bb2b0f22 100644
--- a/drivers/cpufreq/apple-soc-cpufreq.c
+++ b/drivers/cpufreq/apple-soc-cpufreq.c
@@ -135,10 +135,14 @@ 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);
-	struct apple_cpu_priv *priv = policy->driver_data;
+	struct apple_cpu_priv *priv;
 	struct cpufreq_frequency_table *p;
 	unsigned int pstate;
 
+	if (!policy)
+		return 0;
+	priv = policy->driver_data;
+
 	if (priv->info->cur_pstate_mask) {
 		u32 reg = readl_relaxed(priv->reg_base + APPLE_DVFS_STATUS);
 
-- 
2.34.1