[PATCH v2] regulator: core: fix race condition in regulator_put()

[Ashay Jaiswal]

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 <ash...@codeaurora.org>
---
 Changes:
 V1-->V2:
        - Updated comment on top of _regulator_put function
        - Updated lock region

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

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index c2554d8..f70a02c 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -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);
 }
--
Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
hosted by The Linux Foundation

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/