regulator: core: fix race condition in regulator_put()

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>
[lizf: Backported to 3.4:
 - adjust context
 - no need to change the comment]
Signed-off-by: Zefan Li <lizefan@huawei.com>

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index c18f0fd1577fd446b3d986f5823717a6c5af2242..0d71557cf7a3f7a561f05601d104c35060b8a373 100644 (file)
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1395,12 +1395,14 @@ void regulator_put(struct regulator *regulator)
                device_remove_file(regulator->dev, &regulator->dev_attr);
                kfree(regulator->dev_attr.attr.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);
        mutex_unlock(&regulator_list_mutex);