linux-kernel - Re: [PATCH] net-sysfs: Fix memory leak in netdev_register

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Date:   Tue, 19 Mar 2019 12:30:37 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     "wanghai (M)" <wanghai26@...wei.com>
Cc:     Stephen Hemminger <stephen@...workplumber.org>,
        davem@...emloft.net, idosch@...lanox.com,
        alexander.h.duyck@...el.com, tyhicks@...onical.com,
        f.fainelli@...il.com, amritha.nambiar@...el.com, joe@...ches.com,
        dmitry.torokhov@...il.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net-sysfs: Fix memory leak in netdev_register_kobject

On Tue, Mar 19, 2019 at 11:19:24AM +0800, wanghai (M) wrote:
> 
> 在 2019/3/19 0:19, Andy Shevchenko 写道:
> > On Mon, Mar 18, 2019 at 08:57:24AM -0700, Stephen Hemminger wrote:
> > > On Tue, 19 Mar 2019 01:06:57 -0400
> > > Wang Hai <wanghai26@...wei.com> wrote:

> > > This looks a bug in device_add() not here.
> > > In general, it is better for an api to clean up after itself.
> > > Since dev->kobj.name is created in device_add and normally freed
> > > in device_del; why is device_add leaving it behind?
> > It's more likely the bug in syzkaller.
> > 
> > Look at the kobject_cleanup() last lines of code...
> If device_add(dev) or register_queue_kobjects(ndev) fails,
> In register_netdevice(), dev-> reg_state = NETREG_UNINITIALIZED and returns
> an error, causing put_device(&dev-> dev) -> ..-> kobject_cleanup() not to be
> called.

OK, that's true, but your patch is wrong.
See error handling in device_create_groups_vargs() for example.

-- 
With Best Regards,
Andy Shevchenko