[PATCH 4.4 23/65] i2c-dev: dont get i2c adapter via i2c_dev

From: Greg Kroah-Hartman
Date: Tue May 26 2020 - 14:55:31 EST

From: viresh kumar <viresh.kumar@xxxxxxxxxx>

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@xxxxxxxxxx>
Reviewed-by: Jean Delvare <jdelvare@xxxxxxx>
Tested-by: Jean Delvare <jdelvare@xxxxxxx>
Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben.hutchings@xxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
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;