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From: Pavel Skripkin <paskripkin@gmail.com>
To: andrew@lunn.ch, hkallweit1@gmail.com, linux@armlinux.org.uk,
	davem@davemloft.net, kuba@kernel.org, buytenh@marvell.com,
	afleming@freescale.com, dan.carpenter@oracle.com
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	Pavel Skripkin <paskripkin@gmail.com>,
	syzbot+398e7dc692ddbbb4cfec@syzkaller.appspotmail.com
Subject: [PATCH v2 2/2] phy: mdio: fix memory leak
Date: Tue, 28 Sep 2021 23:40:15 +0300	[thread overview]
Message-ID: <55e9785e2ae2eae03c4af850a07e3297c5a0b784.1632861239.git.paskripkin@gmail.com> (raw)
In-Reply-To: <2324212c8d0a713eba0aae3c25635b3ca5c5243f.1632861239.git.paskripkin@gmail.com>

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@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
---

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..2d16a93af1ae 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 realese
+	 * 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


  reply	other threads:[~2021-09-28 20:40 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-27 11:20 [PATCH] " Pavel Skripkin
2021-09-27 19:17 ` Pavel Skripkin
2021-09-28 20:39 ` [PATCH v2 1/2] Revert "net: mdiobus: Fix memory leak in __mdiobus_register" Pavel Skripkin
2021-09-28 20:40   ` Pavel Skripkin [this message]
2021-09-29  6:22     ` [PATCH v2 2/2] phy: mdio: fix memory leak Dan Carpenter
2021-09-29 23:48     ` Jakub Kicinski
2021-09-30  5:55       ` Pavel Skripkin
2021-09-29  6:32   ` [PATCH v2 1/2] Revert "net: mdiobus: Fix memory leak in __mdiobus_register" Xu, Yanfei

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