cpufreq: Initialize policy before making it available for others to use (5a7e56a5) · Commits · 戴 / test

Policy must be fully initialized before it is being made available for use by others. Otherwise cpufreq_cpu_get() would be able to grab a half initialized policy structure that might not have affected_cpus (for example) populated. Then, anybody accessing those fields will get a wrong value and that will lead to unpredictable results. In order to fix this, do all the necessary initialization before we make the policy structure available via cpufreq_cpu_get(). That will guarantee that any code accessing fields of the policy will get correct data from them. Reported-by:

Saravana Kannan <skannan@codeaurora.org> Signed-off-by:

Viresh Kumar <viresh.kumar@linaro.org> [rjw: Changelog] Signed-off-by:

Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/cpufreq.c

+14 −14

Original line number	Diff line number	Diff line
		@@ -1109,6 +1109,20 @@ static int __cpufreq_add_dev(struct device dev, struct subsys_interface sif,
		goto err_set_policy_cpu;
		}

		/* related cpus should atleast have policy->cpus */
		cpumask_or(policy->related_cpus, policy->related_cpus, policy->cpus);

		/*
		* affected cpus must always be the one, which are online. We aren't
		* managing offline cpus here.
		*/
		cpumask_and(policy->cpus, policy->cpus, cpu_online_mask);

		if (!frozen) {
		policy->user_policy.min = policy->min;
		policy->user_policy.max = policy->max;
		}

		write_lock_irqsave(&cpufreq_driver_lock, flags);
		for_each_cpu(j, policy->cpus)
		per_cpu(cpufreq_cpu_data, j) = policy;
		@@ -1162,20 +1176,6 @@ static int __cpufreq_add_dev(struct device dev, struct subsys_interface sif,
		}
		}

		/* related cpus should atleast have policy->cpus */
		cpumask_or(policy->related_cpus, policy->related_cpus, policy->cpus);

		/*
		* affected cpus must always be the one, which are online. We aren't
		* managing offline cpus here.
		*/
		cpumask_and(policy->cpus, policy->cpus, cpu_online_mask);

		if (!frozen) {
		policy->user_policy.min = policy->min;
		policy->user_policy.max = policy->max;
		}

		blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
		CPUFREQ_START, policy);

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