Commit ca42489d authored Apr 06, 2016 by Richard Cochran Committed by Rafael J. Wysocki Apr 07, 2016

intel_idle: Avoid a double free of the per-CPU data.



The helper function, intel_idle_cpuidle_devices_uninit, frees the
globally allocated per-CPU data.  However, this function is invoked
from the hot plug notifier callback at a time when freeing that data
is not safe.

If the call to cpuidle_register_driver() should fail (say, due to lack
of memory), then the driver will free its per-CPU region.  On the
*next* CPU_ONLINE event, the driver will happily use the region again
and even free it again if the failure repeats.

This patch fixes the issue by moving the call to free_percpu() outside
of the helper function at the two call sites that actually need to
free the per-CPU data.

Signed-off-by: Richard Cochran <rcochran@linutronix.de>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

parent e9df69cc

drivers/idle/intel_idle.c

+3 −4

Original line number	Diff line number	Diff line
		@@ -1002,7 +1002,7 @@ static int __init intel_idle_probe(void)

		/*
		* intel_idle_cpuidle_devices_uninit()
		* unregister, free cpuidle_devices
		* Unregisters the cpuidle devices.
		*/
		static void intel_idle_cpuidle_devices_uninit(void)
		{
		@@ -1013,9 +1013,6 @@ static void intel_idle_cpuidle_devices_uninit(void)
		dev = per_cpu_ptr(intel_idle_cpuidle_devices, i);
		cpuidle_unregister_device(dev);
		}

		free_percpu(intel_idle_cpuidle_devices);
		return;
		}

		/*
		@@ -1231,6 +1228,7 @@ static int __init intel_idle_init(void)
		if (retval) {
		cpu_notifier_register_done();
		cpuidle_unregister_driver(&intel_idle_driver);
		free_percpu(intel_idle_cpuidle_devices);
		return retval;
		}
		}
		@@ -1253,6 +1251,7 @@ static void __exit intel_idle_exit(void)
		cpu_notifier_register_done();

		cpuidle_unregister_driver(&intel_idle_driver);
		free_percpu(intel_idle_cpuidle_devices);
		}

		module_init(intel_idle_init);