Re: [PATCH] net: mdiobus: Fix memory leak in __mdiobus_register

[Xu, Yanfei]

On 9/28/21 11:48 PM, Dongliang Mu wrote:
> [Please note: This e-mail is from an EXTERNAL e-mail address]
>
> On Tue, Sep 28, 2021 at 11:41 PM Russell King (Oracle)
> <linux@xxxxxxxxxxxxxxx> 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.

Sorry for my patch, it is my bad. :( And thanks for Pavel's v2 which 
help to revert mine.

Regards,
Yanfei

> > > > 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
>
> > --
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