netdev - Re: [PATCH] net: mdiobus: Fix memory leak in __mdiobus

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Message-ID: <63b18426-c39e-d898-08fb-8bfd05b7be9e@gmail.com>
Date:   Tue, 28 Sep 2021 13:46:56 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     Yanfei Xu <yanfei.xu@...driver.com>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        andrew@...n.ch, hkallweit1@...il.com, linux@...linux.org.uk,
        davem@...emloft.net, kuba@...nel.org, p.zabel@...gutronix.de,
        syzbot+398e7dc692ddbbb4cfec@...kaller.appspotmail.com,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        Dongliang Mu <mudongliangabcd@...il.com>
Subject: Re: [PATCH] net: mdiobus: Fix memory leak in __mdiobus_register

On 9/28/21 13:39, Dan Carpenter wrote:
> No, the syzbot link was correct.
> 

Link is correct, but Yanfei's patch does not fix this bug. Syzbot 
reported leak, that you described below, not the Yanfei one.

> You gave me that link again but I think you must be complaining about
> a different bug which involves mdiobus_free().  Your bug is something
> like this:
> 
> drivers/staging/netlogic/xlr_net.c
>     838          err = mdiobus_register(priv->mii_bus);
>     839          if (err) {
>     840                  mdiobus_free(priv->mii_bus);
> 
> This error path will leak.
> 
>     841                  pr_err("mdio bus registration failed\n");
>     842                  return err;
>     843          }
> 
> Your patch is more complicated than necessary...  Just do:
> 
> diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
> index ee8313a4ac71..c380a30a77bc 100644
> --- a/drivers/net/phy/mdio_bus.c
> +++ b/drivers/net/phy/mdio_bus.c
> @@ -538,6 +538,7 @@ int __mdiobus_register(struct mii_bus *bus, struct module *owner)
>   	bus->dev.groups = NULL;
>   	dev_set_name(&bus->dev, "%s", bus->id);
>   
> +	bus->state = MDIOBUS_UNREGISTERED;
>   	err = device_register(&bus->dev);
>   	if (err) {
>   		pr_err("mii_bus %s failed to register\n", bus->id);
> 
> 
yep, it's the same as mine, but I thought, that MDIOBUS_UNREGISTERED is 
not correct name for this state :) Anyway, thank you for suggestion



With regards,
Pavel Skripkin