netdev - [PATCH v4 2/2] phy: mdio: fix memory leak

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <eceae1429fbf8fa5c73dd2a0d39d525aa905074d.1633024062.git.paskripkin@gmail.com>
Date:   Thu, 30 Sep 2021 20:50:28 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     andrew@...n.ch, hkallweit1@...il.com, linux@...linux.org.uk,
        davem@...emloft.net, kuba@...nel.org, buytenh@...vell.com,
        afleming@...escale.com
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Pavel Skripkin <paskripkin@...il.com>,
        syzbot+398e7dc692ddbbb4cfec@...kaller.appspotmail.com,
        Dan Carpenter <dan.carpenter@...cle.com>
Subject: [PATCH v4 2/2] phy: mdio: fix memory leak

Syzbot reported memory leak in MDIO bus interface, the problem was in
wrong state logic.

MDIOBUS_ALLOCATED indicates 2 states:
	1. Bus is only allocated
	2. Bus allocated and __mdiobus_register() fails, but
	   device_register() was called

In case of device_register() has been called we should call put_device()
to correctly free the memory allocated for this device, but mdiobus_free()
calls just kfree(dev) in case of MDIOBUS_ALLOCATED state

To avoid this behaviour we need to set bus->state to MDIOBUS_UNREGISTERED
_before_ calling device_register(), because put_device() should be
called even in case of device_register() failure.

Link: https://lore.kernel.org/netdev/YVMRWNDZDUOvQjHL@shell.armlinux.org.uk/
Fixes: 46abc02175b3 ("phylib: give mdio buses a device tree presence")
Reported-and-tested-by: syzbot+398e7dc692ddbbb4cfec@...kaller.appspotmail.com
Reviewed-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Pavel Skripkin <paskripkin@...il.com>
---

Changes in v4:
	Fixed typo in comment, thanks to Wong Vee Khee

Changes in v3:
	s/==/=/
	Added Dan's Reviewed-by tag

Changes in v2:
	Removed new state, since MDIOBUS_UNREGISTERED can be used. Also, moved
	bus->state initialization _before_ device_register() call, because
	Yanfei's patch is reverted in [v2 1/2]

---
 drivers/net/phy/mdio_bus.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 53f034fc2ef7..fca8e335d750 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -534,6 +534,13 @@ int __mdiobus_register(struct mii_bus *bus, struct module *owner)
 	bus->dev.groups = NULL;
 	dev_set_name(&bus->dev, "%s", bus->id);
 
+	/* We need to set state to MDIOBUS_UNREGISTERED to correctly release
+	 * the device in mdiobus_free()
+	 *
+	 * State will be updated later in this function in case of success
+	 */
+	bus->state = MDIOBUS_UNREGISTERED;
+
 	err = device_register(&bus->dev);
 	if (err) {
 		pr_err("mii_bus %s failed to register\n", bus->id);
-- 
2.33.0