Re: [ovs-dev] [PATCH net] openvswitch: fix send of uninitialized stack memory in ct limit reply

[Tonghao Zhang]

On Mon, Apr 5, 2021 at 2:01 AM Ilya Maximets <i.maximets@xxxxxxx> wrote:
>
> CC: ovs-dev
>
> On 4/4/21 7:50 PM, Ilya Maximets wrote:
> > 'struct ovs_zone_limit' has more members than initialized in
> > ovs_ct_limit_get_default_limit().  The rest of the memory is a random
> > kernel stack content that ends up being sent to userspace.
> >
> > Fix that by using designated initializer that will clear all
> > non-specified fields.
> >
> > Fixes: 11efd5cb04a1 ("openvswitch: Support conntrack zone limit")
> > Signed-off-by: Ilya Maximets <i.maximets@xxxxxxx>
> > ---
> >  net/openvswitch/conntrack.c | 8 ++++----
> >  1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
> > index c29b0ef1fc27..cadb6a29b285 100644
> > --- a/net/openvswitch/conntrack.c
> > +++ b/net/openvswitch/conntrack.c
> > @@ -2032,10 +2032,10 @@ static int ovs_ct_limit_del_zone_limit(struct nlattr *nla_zone_limit,
> >  static int ovs_ct_limit_get_default_limit(struct ovs_ct_limit_info *info,
> >                                         struct sk_buff *reply)
> >  {
> > -     struct ovs_zone_limit zone_limit;
> > -
> > -     zone_limit.zone_id = OVS_ZONE_LIMIT_DEFAULT_ZONE;
> > -     zone_limit.limit = info->default_limit;
> > +     struct ovs_zone_limit zone_limit = {
> > +             .zone_id = OVS_ZONE_LIMIT_DEFAULT_ZONE,
> > +             .limit   = info->default_limit,
> > +     };
I review the code, userspace don't use the count of ovs_zone_lime
struct, but this patch looks to to me.
Thanks Ilya.
Acked-by: Tonghao Zhang <xiangxia.m.yue@xxxxxxxxx>
> >       return nla_put_nohdr(reply, sizeof(zone_limit), &zone_limit);
> >  }
> >
>
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-- 
Best regards, Tonghao