netdev - Re: [PATCH net 1/2] openvswitch: check for null return for nla_nest

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Date:   Wed, 18 Jul 2018 23:49:07 -0700
From:   Pravin Shelar <pshelar@....org>
To:     Stephen Hemminger <stephen@...workplumber.org>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        ovs dev <dev@...nvswitch.org>,
        Stephen Hemminger <sthemmin@...rosoft.com>
Subject: Re: [PATCH net 1/2] openvswitch: check for null return for nla_nest_start

On Wed, Jul 18, 2018 at 9:12 AM, Stephen Hemminger
<stephen@...workplumber.org> wrote:
> The call to nla_nest_start in conntrack can lead to a NULL
> return so it's possible for attr to become NULL and we can potentially
> get a NULL pointer dereference on attr.  Fix this by checking for
> a NULL return.
>
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=200533
> Fixes: 11efd5cb04a1 ("openvswitch: Support conntrack zone limit")
> Signed-off-by: Stephen Hemminger <stephen@...workplumber.org>
> ---
>  net/openvswitch/conntrack.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
> index 284aca2a252d..2e316f641df8 100644
> --- a/net/openvswitch/conntrack.c
> +++ b/net/openvswitch/conntrack.c
> @@ -2132,6 +2132,8 @@ static int ovs_ct_limit_cmd_get(struct sk_buff *skb, struct genl_info *info)
>                 return PTR_ERR(reply);
>
>         nla_reply = nla_nest_start(reply, OVS_CT_LIMIT_ATTR_ZONE_LIMIT);
> +       if (!nla_reply)
> +               return PRT_ERR(-EMSGSIZE);
>
>         if (a[OVS_CT_LIMIT_ATTR_ZONE_LIMIT]) {
>                 err = ovs_ct_limit_get_zone_limit(
> --
Acked-by: Pravin B Shelar <pshelar@....org>

Thanks.