[PATCH 06/10] intel_idle: Avoid a double free of the per-CPU data.
From: Richard Cochran
Date: Tue Mar 29 2016 - 09:17:02 EST
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.
Cc: Len Brown <lenb@xxxxxxxxxx>
Cc: linux-pm@xxxxxxxxxxxxxxx
Signed-off-by: Richard Cochran <rcochran@xxxxxxxxxxxxx>
---
drivers/idle/intel_idle.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index 5dd741f..0b56872 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -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);
--
2.1.4