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Date:   Tue, 28 Sep 2021 16:41:36 +0100
From:   "Russell King (Oracle)" <linux@armlinux.org.uk>
To:     Dan Carpenter <dan.carpenter@oracle.com>
Cc:     Pavel Skripkin <paskripkin@gmail.com>,
        Yanfei Xu <yanfei.xu@windriver.com>,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>,
        andrew@lunn.ch, hkallweit1@gmail.com, 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
Message-ID: <YVM3sFBIHzEnshvd@shell.armlinux.org.uk>
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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.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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