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Subject[PATCH 4.12 005/196] thermal: cpu_cooling: Avoid accessing potentially freed structures
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4.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Viresh Kumar <viresh.kumar@linaro.org>

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>

---
drivers/thermal/cpu_cooling.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/thermal/cpu_cooling.c
+++ b/drivers/thermal/cpu_cooling.c
@@ -153,8 +153,10 @@ unsigned long cpufreq_cooling_get_level(
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);

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