linux-kernel - [PATCH v2] cpufreq: amd-pstate: add check for cpufreq_cpu

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Message-Id: <20240826133842.5519-1-abelova@astralinux.ru>
Date: Mon, 26 Aug 2024 16:38:41 +0300
From: Anastasia Belova <abelova@...ralinux.ru>
To: Huang Rui <ray.huang@....com>
Cc: Anastasia Belova <abelova@...ralinux.ru>,
	"Gautham R. Shenoy" <gautham.shenoy@....com>,
	Mario Limonciello <mario.limonciello@....com>,
	Perry Yuan <perry.yuan@....com>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	lvc-project@...uxtesting.org
Subject: [PATCH v2] cpufreq: amd-pstate: add check for cpufreq_cpu_get's return value

cpufreq_cpu_get may return NULL. To avoid NULL-dereference check it
and return in case of error.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Anastasia Belova <abelova@...ralinux.ru>
---
v2: remove mixing code and declarations
 drivers/cpufreq/amd-pstate.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 68c616b572f2..f8d474168430 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -656,7 +656,12 @@ static void amd_pstate_adjust_perf(unsigned int cpu,
 	unsigned long max_perf, min_perf, des_perf,
 		      cap_perf, lowest_nonlinear_perf;
 	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
-	struct amd_cpudata *cpudata = policy->driver_data;
+	struct amd_cpudata *cpudata;
+
+	if (!policy)
+		return;
+
+	cpudata = policy->driver_data;
 
 	if (policy->min != cpudata->min_limit_freq || policy->max != cpudata->max_limit_freq)
 		amd_pstate_update_min_max_limit(policy);
@@ -870,11 +875,16 @@ static void amd_pstate_init_prefcore(struct amd_cpudata *cpudata)
 static void amd_pstate_update_limits(unsigned int cpu)
 {
 	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
-	struct amd_cpudata *cpudata = policy->driver_data;
+	struct amd_cpudata *cpudata;
 	u32 prev_high = 0, cur_high = 0;
 	int ret;
 	bool highest_perf_changed = false;
 
+	if (!policy)
+		return;
+
+	cpudata = policy->driver_data;
+
 	mutex_lock(&amd_pstate_driver_lock);
 	if ((!amd_pstate_prefcore) || (!cpudata->hw_prefcore))
 		goto free_cpufreq_put;
-- 
2.30.2