Re: [PATCH v2] nbd_genl_status: null check for nla_nest_start

[Navid Emamdoost <navid.emamdoost@xxxxxxxxx>]

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@xxxxxxx> 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@xxxxxxxxx>
> > Reviewed-by: Bob Liu <bob.liu@xxxxxxxxxx>
> > ---
> >  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.