From: Len Brown <lenb@kernel.org>
To: linux-pm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org,
Richard Cochran <rcochran@linutronix.de>,
Len Brown <len.brown@intel.com>
Subject: [PATCH 07/13] intel_idle: Avoid a double free of the per-CPU data.
Date: Wed, 6 Apr 2016 17:00:53 -0400 [thread overview]
Message-ID: <6c03f13a6f0a7af13deb27fd268a18946cca1ede.1459975717.git.len.brown@intel.com> (raw)
In-Reply-To: <1459976459-2532-1-git-send-email-lenb@kernel.org>
In-Reply-To: <6513da0f2332d2333848af18e374b99f77c124aa.1459975717.git.len.brown@intel.com>
From: Richard Cochran <rcochran@linutronix.de>
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>
---
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 085538a..04fe4df 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -1069,7 +1069,7 @@ 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)
{
@@ -1080,9 +1080,6 @@ 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;
}
/*
@@ -1368,6 +1365,7 @@ 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;
}
}
@@ -1390,6 +1388,7 @@ 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);
--
2.8.0.rc4.16.g56331f8
next prev parent reply other threads:[~2016-04-06 21:01 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-06 21:00 [PATCH 0/13] intel_idle patches ready for upstream Len Brown
2016-04-06 21:00 ` [PATCH 01/13] intel_idle: add BXT support Len Brown
2016-04-06 21:00 ` [PATCH 02/13] intel_idle: remove useless return from void function Len Brown
2016-04-06 21:00 ` [PATCH 03/13] intel_idle: Fix a helper function's return value Len Brown
2016-04-06 21:00 ` [PATCH 04/13] intel_idle: Remove redundant initialization calls Len Brown
2016-04-06 21:00 ` [PATCH 05/13] intel_idle: Fix deallocation order on the driver exit path Len Brown
2016-04-06 21:00 ` [PATCH 06/13] intel_idle: Fix dangling registration on error path Len Brown
2016-04-06 21:00 ` Len Brown [this message]
2016-04-06 21:00 ` [PATCH 08/13] intel_idle: Setup the timer broadcast only on successful driver load Len Brown
2016-04-06 21:00 ` [PATCH 09/13] intel_idle: Don't overreact to a cpuidle registration failure Len Brown
2016-04-06 21:00 ` [PATCH 10/13] intel_idle: Propagate hot plug errors Len Brown
2016-04-06 21:00 ` [PATCH 11/13] intel_idle: Clean up all registered devices on exit Len Brown
2016-04-06 21:00 ` [PATCH 12/13] intel_idle: Add SKX support Len Brown
2016-04-06 21:00 ` [PATCH 13/13] intel_idle: Add KBL support Len Brown
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