linux-kernel - [PATCH 5.4 005/165] regulator: fix use after free issue

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Date:   Sat, 11 Jan 2020 10:48:44 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Wen Yang <wenyang@...ux.alibaba.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 005/165] regulator: fix use after free issue

From: Wen Yang <wenyang@...ux.alibaba.com>

[ Upstream commit 4affd79a125ac91e6a53be843ea3960a8fc00cbb ]

This is caused by dereferencing 'rdev' after put_device() in
the _regulator_get()/_regulator_put() functions.
This patch just moves the put_device() down a bit to avoid the
issue.

Signed-off-by: Wen Yang <wenyang@...ux.alibaba.com>
Cc: Liam Girdwood <lgirdwood@...il.com>
Cc: Mark Brown <broonie@...nel.org>
Cc: linux-kernel@...r.kernel.org
Link: https://lore.kernel.org/r/20191124145835.25999-1-wenyang@linux.alibaba.com
Signed-off-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/regulator/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 87bc06b386a0..d66404920976 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1937,8 +1937,8 @@ struct regulator *_regulator_get(struct device *dev, const char *id,
 	regulator = create_regulator(rdev, dev, id);
 	if (regulator == NULL) {
 		regulator = ERR_PTR(-ENOMEM);
-		put_device(&rdev->dev);
 		module_put(rdev->owner);
+		put_device(&rdev->dev);
 		return regulator;
 	}
 
@@ -2059,13 +2059,13 @@ static void _regulator_put(struct regulator *regulator)
 
 	rdev->open_count--;
 	rdev->exclusive = 0;
-	put_device(&rdev->dev);
 	regulator_unlock(rdev);
 
 	kfree_const(regulator->supply_name);
 	kfree(regulator);
 
 	module_put(rdev->owner);
+	put_device(&rdev->dev);
 }
 
 /**
-- 
2.20.1