On Mon, 2018-01-29 at 13:57 +0100, Greg Kroah-Hartman wrote:
> 4.4-stable review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: Mike Maloney <maloney@xxxxxxxxxx>
>
>
> [ Upstream commit 749439bfac6e1a2932c582e2699f91d329658196 ]
[...]
> --- a/net/ipv6/ip6_output.c
> +++ b/net/ipv6/ip6_output.c
> @@ -1246,14 +1246,16 @@ static int ip6_setup_cork(struct sock *s
> v6_cork->tclass = tclass;
> if (rt->dst.flags & DST_XFRM_TUNNEL)
> mtu = np->pmtudisc >= IPV6_PMTUDISC_PROBE ?
> - rt->dst.dev->mtu : dst_mtu(&rt->dst);
> + READ_ONCE(rt->dst.dev->mtu) : dst_mtu(&rt->dst);
> else
> mtu = np->pmtudisc >= IPV6_PMTUDISC_PROBE ?
> - rt->dst.dev->mtu : dst_mtu(rt->dst.path);
> + READ_ONCE(rt->dst.dev->mtu) : dst_mtu(rt->dst.path);
> if (np->frag_size < mtu) {
> if (np->frag_size)
> mtu = np->frag_size;
> }
> + if (mtu < IPV6_MIN_MTU)
> + return -EINVAL;
This error path appears to leak a reference to rt->dst.
Ben.
> cork->base.fragsize = mtu;
> if (dst_allfrag(rt->dst.path))
> cork->base.flags |= IPCORK_ALLFRAG;
>
>
>
--
Ben Hutchings
Software Developer, Codethink Ltd.