linux-kernel - [PATCH] regulator: fix use after free issue

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Date:   Sun, 24 Nov 2019 22:58:35 +0800
From:   Wen Yang <wenyang@...ux.alibaba.com>
To:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>
Cc:     Wen Yang <wenyang@...ux.alibaba.com>, linux-kernel@...r.kernel.org
Subject: [PATCH] regulator: fix use after free issue

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
---
 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 679ad3d..09a3550 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1938,8 +1938,8 @@ 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;
 	}
 
@@ -2063,13 +2063,13 @@ 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);
 }
 
 /**
-- 
1.8.3.1