From: Viresh Kumar <viresh.kumar@linaro.org>
Date: Tue, 25 Apr 2017 10:27:08 +0000 (+0530)
Subject: thermal: cpu_cooling: Avoid accessing potentially freed structures
X-Git-Tag: C0P2-H0.0--20200415~8132
X-Git-Url: https://git.somdevices.com/?a=commitdiff_plain;h=7cd7b56037ae4cbdfe5e7fa9e41b67ba15199d7f;p=linux.git

thermal: cpu_cooling: Avoid accessing potentially freed structures

commit 289d72afddf83440117c35d864bf0c6309c1d011 upstream.

After the lock is dropped, it is possible that the cpufreq_dev gets
freed before we call get_level() and that can cause kernel to crash.

Drop the lock after we are done using the structure.

Fixes: 02373d7c69b4 ("thermal: cpu_cooling: fix lockdep problems in cpu_cooling")
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Tested-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
index 9ce0e9eef923..f49d2989d000 100644
--- a/drivers/thermal/cpu_cooling.c
+++ b/drivers/thermal/cpu_cooling.c
@@ -191,8 +191,10 @@ unsigned long cpufreq_cooling_get_level(unsigned int cpu, unsigned int freq)
 	mutex_lock(&cooling_list_lock);
 	list_for_each_entry(cpufreq_dev, &cpufreq_dev_list, node) {
 		if (cpumask_test_cpu(cpu, &cpufreq_dev->allowed_cpus)) {
+			unsigned long level = get_level(cpufreq_dev, freq);
+
 			mutex_unlock(&cooling_list_lock);
-			return get_level(cpufreq_dev, freq);
+			return level;
 		}
 	}
 	mutex_unlock(&cooling_list_lock);