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From: Pavel Skripkin <paskripkin@gmail.com>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Yanfei Xu <yanfei.xu@windriver.com>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	andrew@lunn.ch, hkallweit1@gmail.com, linux@armlinux.org.uk,
	davem@davemloft.net, kuba@kernel.org, p.zabel@pengutronix.de,
	syzbot+398e7dc692ddbbb4cfec@syzkaller.appspotmail.com,
	linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
	Dongliang Mu <mudongliangabcd@gmail.com>
Subject: Re: [PATCH] net: mdiobus: Fix memory leak in __mdiobus_register
Date: Tue, 28 Sep 2021 14:45:39 +0300	[thread overview]
Message-ID: <c86fecd6-6412-fec8-1dce-81e99c059e38@gmail.com> (raw)
In-Reply-To: <20210928113055.GN2083@kadam>

On 9/28/21 14:30, Dan Carpenter wrote:
> On Tue, Sep 28, 2021 at 02:09:06PM +0300, Pavel Skripkin wrote:
>> On 9/28/21 14:06, Pavel Skripkin wrote:
>> > > It's not actually the same.  The state has to be set before the
>> > > device_register() or there is still a leak.
>> > > 
>> > Ah, I see... I forgot to handle possible device_register() error. Will
>> > send v2 soon, thank you
>> > 
>> > 
>> > 
>> Wait... Yanfei's patch is already applied to net tree and if I understand
>> correctly, calling put_device() 2 times will cause UAF or smth else.
>> 
> 
> Yes.  It causes a UAF.
> 
> Huh...  You're right that the log should say "failed to register".  But
> I don't think that's the correct syzbot link for your patch either
> because I don't think anyone calls mdiobus_free() if
> __devm_mdiobus_register() fails.  I have looked at these callers.  It
> would be a bug as well.
> 

mdiobus_free() is called in case of ->probe() failure, because devres 
clean up function for bus is devm_mdiobus_free(). It simply calls 
mdiobus_free().


So, i imagine following calltrace:

ax88772_bind
   ax88772_init_mdio
     devm_mdiobus_alloc() <- bus registered as devres
     devm_mdiobus_register() <- fail (->probe failure)

...

devres_release_all
   mdiobus_free()


Also, syzbot has tested my patch :)

> Anyway, your patch is required and the __devm_mdiobus_register()
> function has leaks as well.  And perhaps there are more bugs we have not
> discovered.
> 
> regards,
> dan carpenter
> 



With regards,
Pavel Skripkin

  reply	other threads:[~2021-09-28 11:45 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-26  4:53 [PATCH] net: mdiobus: Fix memory leak in __mdiobus_register Yanfei Xu
2021-09-26 15:34 ` Andrew Lunn
2021-09-27 12:30 ` patchwork-bot+netdevbpf
2021-09-28  8:55 ` Dan Carpenter
2021-09-28  9:26   ` Dan Carpenter
2021-09-28  9:45     ` Pavel Skripkin
2021-09-28 10:39       ` Dan Carpenter
2021-09-28 10:46         ` Pavel Skripkin
2021-09-28 10:55           ` Dan Carpenter
2021-09-28 11:04             ` Pavel Skripkin
2021-09-28 10:59           ` Dan Carpenter
2021-09-28 11:06             ` Pavel Skripkin
2021-09-28 11:09               ` Pavel Skripkin
2021-09-28 11:30                 ` Dan Carpenter
2021-09-28 11:45                   ` Pavel Skripkin [this message]
2021-09-28 12:23                     ` Dan Carpenter
2021-09-28 12:58                   ` Russell King (Oracle)
2021-09-28 13:52                     ` Dan Carpenter
2021-09-28 15:41                       ` Russell King (Oracle)
2021-09-28 15:48                         ` Dongliang Mu
2021-09-29  2:05                           ` Xu, Yanfei
2021-09-28 13:11 ` Russell King (Oracle)
2021-09-29 21:31 ` Denis Efremov

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