linux-kernel - [PATCH] regulator: core: fix race condition in regulator

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Date:	Wed,  7 Jan 2015 19:21:23 +0530
From:	Ashay Jaiswal <ashayj@...eaurora.org>
To:	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>
Cc:	linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
	Anirudh Ghayal <aghayal@...eaurora.org>,
	Ashay Jaiswal <ashayj@...eaurora.org>
Subject: [PATCH] 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 without
holding the regulator device's mutex, resulting in a race condition
between any regulator operation which traverses the consumer list
and regulator_put() which releases the consumer regulator.
Fix this race condition by holding the regulator device's mutex while
removing and releasing the consumer regulator.

Signed-off-by: Ashay Jaiswal <ashayj@...eaurora.org>
---
 drivers/regulator/core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index c2554d8..3845397 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1498,6 +1498,7 @@ static void _regulator_put(struct regulator *regulator)

 	rdev = regulator->rdev;

+	mutex_lock(&rdev->mutex);
 	debugfs_remove_recursive(regulator->debugfs);

 	/* remove any sysfs entries */
@@ -1511,6 +1512,7 @@ static void _regulator_put(struct regulator *regulator)
 	rdev->exclusive = 0;

 	module_put(rdev->owner);
+	mutex_unlock(&rdev->mutex);
 }

 /**
--
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