linux-kernel - Re: [PATCH 1/5] lightnvm: Fix uninitialized pointer in nvm_remove

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Date:   Wed, 29 May 2019 10:12:45 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Matias Bjørling <mb@...htnvm.io>
Cc:     Igor Konopko <igor.j.konopko@...el.com>,
        David Howells <dhowells@...hat.com>,
        "Mohit P . Tahiliani" <tahiliani@...k.edu.in>,
        Takashi Sakamoto <o-takashi@...amocchi.jp>,
        Eran Ben Elisha <eranbe@...lanox.com>,
        Jiri Pirko <jiri@...lanox.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Clemens Ladisch <clemens@...isch.de>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, Joe Perches <joe@...ches.com>,
        Arnd Bergmann <arnd@...db.de>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        linux-block@...r.kernel.org, netdev <netdev@...r.kernel.org>,
        linux-afs@...ts.infradead.org,
        ALSA Development Mailing List <alsa-devel@...a-project.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/5] lightnvm: Fix uninitialized pointer in nvm_remove_tgt()

Hi Matias,

On Wed, May 29, 2019 at 10:08 AM Matias Bjørling <mb@...htnvm.io> wrote:
> On 5/28/19 4:24 PM, Geert Uytterhoeven wrote:
> > With gcc 4.1:
> >
> >      drivers/lightnvm/core.c: In function ‘nvm_remove_tgt’:
> >      drivers/lightnvm/core.c:510: warning: ‘t’ is used uninitialized in this function
> >
> > Indeed, if no NVM devices have been registered, t will be an
> > uninitialized pointer, and may be dereferenced later.  A call to
> > nvm_remove_tgt() can be triggered from userspace by issuing the
> > NVM_DEV_REMOVE ioctl on the lightnvm control device.
> >
> > Fix this by preinitializing t to NULL.
> >
> > Fixes: 843f2edbdde085b4 ("lightnvm: do not remove instance under global lock")
> > Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
> > ---
> >   drivers/lightnvm/core.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/lightnvm/core.c b/drivers/lightnvm/core.c
> > index 0df7454832efe082..aa017f48eb8c588c 100644
> > --- a/drivers/lightnvm/core.c
> > +++ b/drivers/lightnvm/core.c
> > @@ -492,7 +492,7 @@ static void __nvm_remove_target(struct nvm_target *t, bool graceful)
> >    */
> >   static int nvm_remove_tgt(struct nvm_ioctl_remove *remove)
> >   {
> > -     struct nvm_target *t;
> > +     struct nvm_target *t = NULL;
> >       struct nvm_dev *dev;
> >
> >       down_read(&nvm_lock);
> >
>
> Thanks Geert. Would you like me to carry the patch?

Yes please. Thanks!

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