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From: Dan Carpenter <dan.carpenter@oracle.com>
To: Anders Roxell <anders.roxell@linaro.org>
Cc: erico.nunes@datacom.ind.br, wsa@the-dreams.de,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: BUG: KASAN: i2c dev use after free
Date: Mon, 4 Mar 2019 18:37:14 +0300	[thread overview]
Message-ID: <20190304153714.GD13452@kadam> (raw)
In-Reply-To: <CADYN=9KkjPSP4KJ+AzG=Njq49zJ5fbWNZ4V_jOvHkq_kt0biyA@mail.gmail.com>

I wasn't trying to fix anything so complicated as this, it was a
more obvious use after free.  It does feel intuitively that we should
call device_destroy() before the cdev_del() so that it's in the reverse
order from how it was allocated but I don't see any reason to think
that will make a difference.

---
 drivers/i2c/i2c-dev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index 3f7b9af11137..7e85e2cf26c1 100644
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -687,9 +687,9 @@ static int i2cdev_detach_adapter(struct device *dev, void *dummy)
 	if (!i2c_dev) /* attach_adapter must have failed */
 		return 0;
 
+	device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
 	cdev_del(&i2c_dev->cdev);
 	put_i2c_dev(i2c_dev);
-	device_destroy(i2c_dev_class, MKDEV(I2C_MAJOR, adap->nr));
 
 	pr_debug("i2c-dev: adapter [%s] unregistered\n", adap->name);
 	return 0;
-- 
2.17.1


  reply	other threads:[~2019-03-04 15:37 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-04 14:11 BUG: KASAN: i2c dev use after free Anders Roxell
2019-03-04 15:37 ` Dan Carpenter [this message]
2019-03-06 17:28   ` Anders Roxell
2020-03-22 16:18 ` Wolfram Sang

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