linux-kernel - Re: [PATCH 1/2] vfio: platform: Fix reset module leak in error path

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Date:   Mon, 26 Feb 2018 10:47:41 +0100
From:   Auger Eric <eric.auger@...hat.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Geert Uytterhoeven <geert+renesas@...der.be>,
        Baptiste Reynal <b.reynal@...tualopensystems.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        KVM list <kvm@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] vfio: platform: Fix reset module leak in error path

Hi Geert,

On 21/02/18 17:07, Geert Uytterhoeven wrote:
> Hi Eric,
> 
> On Wed, Feb 14, 2018 at 10:32 AM, Geert Uytterhoeven
> <geert@...ux-m68k.org> wrote:
>> On Wed, Feb 14, 2018 at 9:36 AM, Auger Eric <eric.auger@...hat.com> wrote:
>>> If I am not wrong we also leak the reset_module if
>>> vfio_platform_get_reset() fails to find the reset function (of_reset ==
>>> NULL), in which case we should do the module_put() in
>>> vfio_platform_get_reset().
>>
>> Correct. Will look into fixing it...
> 
> Upon second look, I don't think there's a leak in vfio_platform_get_reset().
> 
> If try_module_get() succeeded, there will always be a valid reset function
> (unless someone registered a vfio_reset_handler with a NULL reset function).
Hum yes, you are right. So the code is fine as is. Sorry for the noise.

Thanks

Eric


> 
> Or do you mean the call to request_module()?
> That one doesn't do a module_get(), it merely tries to load a module.
> Hence there's no need to do a module_put() afterwards.
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds
>