linux-kernel - [PATCH 4.4 23/65] i2c-dev: dont get i2c adapter via i2c

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Date:   Tue, 26 May 2020 20:52:42 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Viresh Kumar <viresh.kumar@...aro.org>,
        Jean Delvare <jdelvare@...e.de>,
        Wolfram Sang <wsa@...-dreams.de>,
        Ben Hutchings <ben.hutchings@...ethink.co.uk>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.4 23/65] i2c-dev: dont get i2c adapter via i2c_dev

From: viresh kumar <viresh.kumar@...aro.org>

commit 5136ed4fcb05cd4981cc6034a11e66370ed84789 upstream.

There is no code protecting i2c_dev to be freed after it is returned
from i2c_dev_get_by_minor() and using it to access the value which we
already have (minor) isn't safe really.

Avoid using it and get the adapter directly from 'minor'.

Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
Reviewed-by: Jean Delvare <jdelvare@...e.de>
Tested-by: Jean Delvare <jdelvare@...e.de>
Signed-off-by: Wolfram Sang <wsa@...-dreams.de>
Signed-off-by: Ben Hutchings <ben.hutchings@...ethink.co.uk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/i2c/i2c-dev.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index e5cd307ebfc9..5543b49e2e05 100644
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -492,13 +492,8 @@ static int i2cdev_open(struct inode *inode, struct file *file)
 	unsigned int minor = iminor(inode);
 	struct i2c_client *client;
 	struct i2c_adapter *adap;
-	struct i2c_dev *i2c_dev;
-
-	i2c_dev = i2c_dev_get_by_minor(minor);
-	if (!i2c_dev)
-		return -ENODEV;
 
-	adap = i2c_get_adapter(i2c_dev->adap->nr);
+	adap = i2c_get_adapter(minor);
 	if (!adap)
 		return -ENODEV;
 
-- 
2.25.1