Subject: Re: [PATCH net 1/4] mpls: validate L2 via address length

From: roopa <[email-masked]>
Date: Fri, 11 Dec 2015 14:51:04 -0800

On 12/10/15, 11:30 AM, Robert Shearman wrote:
> If an L2 via address for an mpls nexthop is specified, the length of
> the L2 address must match that expected by the output device,
> otherwise it could access memory beyond the end of the via address
> buffer in the route.
>
> This check was present prior to commit f8efb73c97e2 ("mpls: multipath
> route support"), but got lost in the refactoring, so add it back,
> applying it to all nexthops in multipath routes.
>
> Fixes: f8efb73c97e2 ("mpls: multipath route support")
> Signed-off-by: Robert Shearman <[email-masked]>
> ---
>  net/mpls/af_mpls.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
> index c70d750148b6..3be29cb1f658 100644
> --- a/net/mpls/af_mpls.c
> +++ b/net/mpls/af_mpls.c
> @@ -534,6 +534,10 @@ static int mpls_nh_assign_dev(struct net *net, struct mpls_route *rt,
>  	if (!mpls_dev_get(dev))
>  		goto errout;
>  
> +	if ((nh->nh_via_table == NEIGH_LINK_TABLE) &&
> +	    (dev->addr_len != nh->nh_via_alen))
> +		goto errout;
> +
>
Robert, seems like the right place for this check is nla_get_via ?