[PATCH 3.14 24/33] regulator: core: fix race condition in regulator_put()

Greg Kroah-Hartman
2015-02-03T23:18:42Z

From: Ashay Jaiswal <ashayj@codeaurora.org>

commit 83b0302d347a49f951e904184afe57ac3723476e upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/regulator/core.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1479,7 +1479,7 @@ struct regulator *regulator_get_optional
}
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;
@@ -1494,12 +1494,14 @@ static void _regulator_put(struct regula
/* 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);
}