Commit 83b0302d authored Jan 08, 2015 by Ashay Jaiswal Committed by Mark Brown Jan 08, 2015

regulator: core: fix race condition in regulator_put()



The regulator framework maintains a list of consumer regulators
for a regulator device and protects it from concurrent access using
the regulator device's mutex lock.

In the case of regulator_put() the consumer is removed and regulator
device's parameters are updated without holding the regulator device's
mutex. This would lead to a race condition between the regulator_put()
and any function which traverses the consumer list or modifies regulator
device's parameters.
Fix this race condition by holding the regulator device's mutex in case
of regulator_put.

Signed-off-by: Ashay Jaiswal <ashayj@codeaurora.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org

parent 97bf6af1

drivers/regulator/core.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -1488,7 +1488,7 @@ struct regulator regulator_get_optional(struct device dev, const char *id)
		}
		EXPORT_SYMBOL_GPL(regulator_get_optional);

		/* Locks held by regulator_put() */
		/* regulator_list_mutex lock held by regulator_put() */
		static void _regulator_put(struct regulator *regulator)
		{
		struct regulator_dev *rdev;
		@@ -1503,12 +1503,14 @@ static void _regulator_put(struct regulator *regulator)
		/* remove any sysfs entries */
		if (regulator->dev)
		sysfs_remove_link(&rdev->dev.kobj, regulator->supply_name);
		mutex_lock(&rdev->mutex);
		kfree(regulator->supply_name);
		list_del(&regulator->list);
		kfree(regulator);

		rdev->open_count--;
		rdev->exclusive = 0;
		mutex_unlock(&rdev->mutex);

		module_put(rdev->owner);
		}

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