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patch "thermal: cpu_cooling: Avoid accessing potentially freed structures" added to thermal-soc tree

PATCH Eduardo Valentin 1 participant 1 message May 24, 2017

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This is a simple automated notification to let you know that I've just added the patch titled

thermal: cpu_cooling: Avoid accessing potentially freed structures

to my thermal-soc git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/evalenti/linux-soc-thermal.git
in the linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will also be merged in the next major kernel release during the merge window.

If you have any questions about this process, please let me know.

All the best,

Eduardo Valentin

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Quoted 1 line

From 2e5103b6131932cad8f6bfc28c1940bd3c2b9ca9 Mon Sep 17 00:00:00 2001

From: Viresh Kumar <[email protected]>
Date: Tue, 25 Apr 2017 15:57:08 +0530
Subject: thermal: cpu_cooling: Avoid accessing potentially freed structures

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.

Cc 4.2+ <[email protected]> # 4.2+
Fixes 02373d7c69b4 ("thermal: cpu_cooling: fix lockdep problems in cpu_cooling")
---
 drivers/thermal/cpu_cooling.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
drivers/thermal/cpu_cooling.c +3 -1
index 69d0f43..be29489 100644
@@ -153,8 +153,10 @@ 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);
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