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

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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>
This commit is contained in:
Richard Cochran
2016-04-06 17:00:53 -04:00
committed by Rafael J. Wysocki
parent e9df69ccd1
commit ca42489d9e
1 changed files with 3 additions and 4 deletions
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7
drivers/idle/intel_idle.c
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@@ -1002,7 +1002,7 @@ static int __init intel_idle_probe(void)
/* /*
* intel_idle_cpuidle_devices_uninit() * intel_idle_cpuidle_devices_uninit()
* unregister, free cpuidle_devices * Unregisters the cpuidle devices.
*/ */
static void intel_idle_cpuidle_devices_uninit(void) 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); dev = per_cpu_ptr(intel_idle_cpuidle_devices, i);
cpuidle_unregister_device(dev); cpuidle_unregister_device(dev);
} }
free_percpu(intel_idle_cpuidle_devices);
return;
} }
/* /*
@@ -1231,6 +1228,7 @@ static int __init intel_idle_init(void)
if (retval) { if (retval) {
cpu_notifier_register_done(); cpu_notifier_register_done();
cpuidle_unregister_driver(&intel_idle_driver); cpuidle_unregister_driver(&intel_idle_driver);
free_percpu(intel_idle_cpuidle_devices);
return retval; return retval;
} }
} }
@@ -1253,6 +1251,7 @@ static void __exit intel_idle_exit(void)
cpu_notifier_register_done(); cpu_notifier_register_done();
cpuidle_unregister_driver(&intel_idle_driver); cpuidle_unregister_driver(&intel_idle_driver);
free_percpu(intel_idle_cpuidle_devices);
} }
module_init(intel_idle_init); module_init(intel_idle_init);