linux-kernel - Re: [PATCH] nvmem: core: fix leaks on registration errors

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Date:   Wed, 17 May 2017 10:51:05 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Andrey Smirnov <andrew.smirnov@...il.com>
Cc:     Johan Hovold <johan@...nel.org>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        stable <stable@...r.kernel.org>, Andrew Lunn <andrew@...n.ch>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject: Re: [PATCH] nvmem: core: fix leaks on registration errors

On Tue, May 16, 2017 at 02:28:28PM -0700, Andrey Smirnov wrote:
> On Tue, May 16, 2017 at 6:44 AM, Johan Hovold <johan@...nel.org> wrote:
> > Make sure to deregister and release the nvmem device and underlying
> > memory on registration errors.
> >
> > Note that the private data must be freed using put_device() once the
> > struct device has been initialised.
> >
> > Also note that there's a related reference leak in the deregistration
> > function as reported by Mika Westerberg which is being fixed separately.
> >
> > Fixes: b6c217ab9be6 ("nvmem: Add backwards compatibility support for older EEPROM drivers.")
> > Fixes: eace75cfdcf7 ("nvmem: Add a simple NVMEM framework for nvmem providers")
> > Cc: stable <stable@...r.kernel.org>     # 4.3
> > Cc: Andrew Lunn <andrew@...n.ch>
> > Cc: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
> > Cc: Mika Westerberg <mika.westerberg@...ux.intel.com>
> > Signed-off-by: Johan Hovold <johan@...nel.org>
> > ---
> 
> I submitted identical patch to fix this about a month ago here:
> 
> lkml.kernel.org/r/20170418142454.23921-1-andrew.smirnov@...il.com

Oh, and you fixed up both the registration and deregistration leaks in
your series too. Looks like the maintainer is on vacation now so perhaps
we'll see a third independent fix for these bugs soon. ;) 

As for your series, I prefer this version for nvmem_register due to the
difference in error label naming (named after what they do rather than
where they are used), but as I also mentioned to Mika, I think just
adding the missing put_device to nvmem_unregister as you did is
preferred.

But the important thing is that this gets fixed.

> so, FWIW,
> 
> Acked-by: Andrey Smirnov <andrew.smirnov@...il.com>

Thanks,
Johan

> >  drivers/nvmem/core.c | 13 ++++++++-----
> >  1 file changed, 8 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
> > index 8c830a80a648..6cf916d9db6d 100644
> > --- a/drivers/nvmem/core.c
> > +++ b/drivers/nvmem/core.c
> > @@ -489,21 +489,24 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
> >
> >         rval = device_add(&nvmem->dev);
> >         if (rval)
> > -               goto out;
> > +               goto err_put_device;
> >
> >         if (config->compat) {
> >                 rval = nvmem_setup_compat(nvmem, config);
> >                 if (rval)
> > -                       goto out;
> > +                       goto err_device_del;
> >         }
> >
> >         if (config->cells)
> >                 nvmem_add_cells(nvmem, config);
> >
> >         return nvmem;
> > -out:
> > -       ida_simple_remove(&nvmem_ida, nvmem->id);
> > -       kfree(nvmem);
> > +
> > +err_device_del:
> > +       device_del(&nvmem->dev);
> > +err_put_device:
> > +       put_device(&nvmem->dev);
> > +
> >         return ERR_PTR(rval);
> >  }
> >  EXPORT_SYMBOL_GPL(nvmem_register);
> > --
> > 2.13.0
> >