netdev - Re: [PATCH net v3 2/2] net: avoid infinite loop in mpls_gso_segment when mpls

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 9 Mar 2021 09:29:31 -0500
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     Balazs Nemeth <bnemeth@...hat.com>
Cc:     Network Development <netdev@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        David Ahern <dsahern@...il.com>,
        David Miller <davem@...emloft.net>,
        virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH net v3 2/2] net: avoid infinite loop in mpls_gso_segment
 when mpls_hlen == 0

On Tue, Mar 9, 2021 at 6:32 AM Balazs Nemeth <bnemeth@...hat.com> wrote:
>
> A packet with skb_inner_network_header(skb) == skb_network_header(skb)
> and ETH_P_MPLS_UC will prevent mpls_gso_segment from pulling any headers
> from the packet. Subsequently, the call to skb_mac_gso_segment will
> again call mpls_gso_segment with the same packet leading to an infinite
> loop. In addition, ensure that the header length is a multiple of four,
> which should hold irrespective of the number of stacked labels.
>
> Signed-off-by: Balazs Nemeth <bnemeth@...hat.com>

Acked-by: Willem de Bruijn <willemb@...gle.com>

The compiler will convert that modulo into a cheap & (ETH_HLEN - 1)
test for this constant.