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

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Date:   Sun, 4 Apr 2021 20:01:34 +0200
From:   Ilya Maximets <i.maximets@....org>
To:     Ilya Maximets <i.maximets@....org>,
        Pravin B Shelar <pshelar@....org>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Yi-Hung Wei <yihung.wei@...il.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, ovs dev <dev@...nvswitch.org>
Subject: Re: [PATCH net] openvswitch: fix send of uninitialized stack memory
 in ct limit reply

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@....org>
> ---
>  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,
> +	};
>  
>  	return nla_put_nohdr(reply, sizeof(zone_limit), &zone_limit);
>  }
>