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From: Dongliang Mu <mudongliangabcd@gmail.com>
To: "Russell King (Oracle)" <linux@armlinux.org.uk>
Cc: Dan Carpenter <dan.carpenter@oracle.com>,
	Pavel Skripkin <paskripkin@gmail.com>,
	Yanfei Xu <yanfei.xu@windriver.com>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	andrew@lunn.ch, hkallweit1@gmail.com,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	p.zabel@pengutronix.de,
	syzbot <syzbot+398e7dc692ddbbb4cfec@syzkaller.appspotmail.com>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	"open list:NETWORKING [GENERAL]" <netdev@vger.kernel.org>
Subject: Re: [PATCH] net: mdiobus: Fix memory leak in __mdiobus_register
Date: Tue, 28 Sep 2021 23:48:23 +0800	[thread overview]
Message-ID: <CAD-N9QXHcrv+6SJSOz3NyBkAnze2wVf_azYmjbGCVd5Ge_OQng@mail.gmail.com> (raw)
In-Reply-To: <YVM3sFBIHzEnshvd@shell.armlinux.org.uk>

On Tue, Sep 28, 2021 at 11:41 PM Russell King (Oracle)
<linux@armlinux.org.uk> wrote:
>
> On Tue, Sep 28, 2021 at 04:52:07PM +0300, Dan Carpenter wrote:
> > On Tue, Sep 28, 2021 at 01:58:00PM +0100, Russell King (Oracle) wrote:
> > >
> > > This thread seems to be getting out of hand.
> >
> > The thread was closed.  We need to revert Yanfei's patch and apply
> > Pavel's patch.  He's going to resend.
> >
> > > So, I would suggest a simple fix is to set bus->state to
> > > MDIOBUS_UNREGISTERED immediately _after_ the successful
> > > device_register().
> >
> > Not after.  It has to be set to MDIOBUS_UNREGISTERED if device_register()
> > fails, otherwise there will still be a leak.
>
> Ah yes, you are correct - the device name may not be freed. Also...
>
>  * NOTE: _Never_ directly free @dev after calling this function, even
>  * if it returned an error! Always use put_device() to give up your
>  * reference instead.
>
> So yes, we must set to MDIOBUS_UNREGISTERED even if device_register()
> fails.
>

So we have reached an agreement. Pavel's patch fixes the syzbot link
[1], other than Yanfei's patch. However, Yanfei's patch also fixes
another memory link nearby.

Right?

[1] https://syzkaller.appspot.com/bug?id=fa99459691911a0369622248e0f4e3285fcedd97

> --
> RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
> FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

  reply	other threads:[~2021-09-28 15:49 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-26  4:53 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
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 [this message]
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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