linux-kernel - [PATCH 3.2 33/61] driver core: bus: Fix a potential double free

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Message-ID: <lsq.1511316666.697427939@decadent.org.uk>
Date:   Wed, 22 Nov 2017 02:11:06 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "Christophe JAILLET" <christophe.jaillet@...adoo.fr>
Subject: [PATCH 3.2 33/61] driver core: bus: Fix a potential double free

3.2.96-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Christophe JAILLET <christophe.jaillet@...adoo.fr>

commit 0f9b011d3321ca1079c7a46c18cb1956fbdb7bcb upstream.

The .release function of driver_ktype is 'driver_release()'.
This function frees the container_of this kobject.

So, this memory must not be freed explicitly in the error handling path of
'bus_add_driver()'. Otherwise a double free will occur.

Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/base/bus.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -684,7 +684,7 @@ int bus_add_driver(struct device_driver
 
 out_unregister:
 	kobject_put(&priv->kobj);
-	kfree(drv->p);
+	/* drv->p is freed in driver_release()  */
 	drv->p = NULL;
 out_put_bus:
 	bus_put(bus);