Messages in this thread Patch in this message | | | From | Pavel Skripkin <> | Subject | [PATCH v4 2/2] phy: mdio: fix memory leak | Date | Thu, 30 Sep 2021 20:50:28 +0300 |
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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 Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Pavel Skripkin <paskripkin@gmail.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
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