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 <20190729164226.22632-1-navid.emamdoost@gmail.com> <20190910113521.GA9895@unicorn.suse.cz>
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From:   Navid Emamdoost <navid.emamdoost@gmail.com>
Date:   Wed, 16 Oct 2019 21:17:21 -0500
Message-ID: <CAEkB2ES8rc4kkPwA+okfMa9CpFoDqmt=tx8H8vHZKBCfw9L_tg@mail.gmail.com>
Subject: Re: [PATCH v2] nbd_genl_status: null check for nla_nest_start
To:     Michal Kubecek <mkubecek@suse.cz>
Cc:     Josef Bacik <josef@toxicpanda.com>, Kangjie Lu <kjlu@umn.edu>,
        Stephen McCamant <smccaman@umn.edu>, secalert@redhat.com,
        Navid Emamdoost <emamd001@umn.edu>,
        Jens Axboe <axboe@kernel.dk>, linux-block@vger.kernel.org,
        nbd@other.debian.org, LKML <linux-kernel@vger.kernel.org>
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Hi Michal, please check v3 at https://lore.kernel.org/patchwork/patch/1126650/


Thanks,
Navid.

On Tue, Sep 10, 2019 at 6:35 AM Michal Kubecek <mkubecek@suse.cz> wrote:
>
> (Just stumbled upon this patch when link to it came with a CVE bug report.)
>
> On Mon, Jul 29, 2019 at 11:42:26AM -0500, Navid Emamdoost wrote:
> > nla_nest_start may fail and return NULL. The check is inserted, and
> > errno is selected based on other call sites within the same source code.
> > Update: removed extra new line.
> >
> > Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
> > Reviewed-by: Bob Liu <bob.liu@oracle.com>
> > ---
> >  drivers/block/nbd.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
> > index 9bcde2325893..2410812d1e82 100644
> > --- a/drivers/block/nbd.c
> > +++ b/drivers/block/nbd.c
> > @@ -2149,6 +2149,11 @@ static int nbd_genl_status(struct sk_buff *skb, struct genl_info *info)
> >       }
> >
> >       dev_list = nla_nest_start_noflag(reply, NBD_ATTR_DEVICE_LIST);
> > +     if (!dev_list) {
> > +             ret = -EMSGSIZE;
> > +             goto out;
> > +     }
> > +
> >       if (index == -1) {
> >               ret = idr_for_each(&nbd_index_idr, &status_cb, reply);
> >               if (ret) {
>
> You should also call nlmsg_free(reply) when you bail out so that you
> don't introduce a memory leak.
>
> Michal Kubecek


-- 
Navid.