From: Henry Willard Date: Wed, 15 Aug 2018 00:01:02 +0000 (-0700) Subject: cpufreq: governor: Avoid accessing invalid governor_data X-Git-Tag: android-x86-8.1-r1~398^2^2 X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=2a3eb51e30b9ac66fe1b75877627a7e4aaeca24a;p=android-x86%2Fkernel.git cpufreq: governor: Avoid accessing invalid governor_data If cppc_cpufreq.ko is deleted at the same time that tuned-adm is changing profiles, there is a small chance that a race can occur between cpufreq_dbs_governor_exit() and cpufreq_dbs_governor_limits() resulting in a system failure when the latter tries to use policy->governor_data that has been freed by the former. This patch uses gov_dbs_data_mutex to synchronize access. Fixes: e788892ba3cc (cpufreq: governor: Get rid of governor events) Signed-off-by: Henry Willard [ rjw: Subject, minor white space adjustment ] Cc: 4.8+ # 4.8+ Signed-off-by: Rafael J. Wysocki --- diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c index 1d50e97d49f1..6d53f7d9fc7a 100644 --- a/drivers/cpufreq/cpufreq_governor.c +++ b/drivers/cpufreq/cpufreq_governor.c @@ -555,12 +555,20 @@ EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_stop); void cpufreq_dbs_governor_limits(struct cpufreq_policy *policy) { - struct policy_dbs_info *policy_dbs = policy->governor_data; + struct policy_dbs_info *policy_dbs; + + /* Protect gov->gdbs_data against cpufreq_dbs_governor_exit() */ + mutex_lock(&gov_dbs_data_mutex); + policy_dbs = policy->governor_data; + if (!policy_dbs) + goto out; mutex_lock(&policy_dbs->update_mutex); cpufreq_policy_apply_limits(policy); gov_update_sample_delay(policy_dbs, 0); - mutex_unlock(&policy_dbs->update_mutex); + +out: + mutex_unlock(&gov_dbs_data_mutex); } EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_limits);