From: "Michael S. Tsirkin" <mst@redhat.com>
To: Pranjal Kumar Singh <pranjalksingh92@gmail.com>
Cc: cve@kernel.org, netdev <netdev@vger.kernel.org>,
Pablo Neira Ayuso <pablo@netfilter.org>,
Jozsef Kadlecsik <kadlec@netfilter.org>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Willem de Bruijn <willemb@google.com>,
Paulos Yibelo <habte.yibelo@gmail.com>,
openvswitch <dev@openvswitch.org>,
stable@vger.kernel.org, "fw@strlen.de" <fw@strlen.de>
Subject: Re: Kernel bug report: unguarded deferred skb_checksum_help() writes corrupt the previously-validated IPv6 fixed header (IPv6 counterpart of commit 6785011f8b16, "ipv4: validate checksum_start before completing checksum")
Date: Mon, 19 Oct 2026 04:50:10 -0400 [thread overview]
Message-ID: <20261019044815-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <CA+UYBZDMpqq989aWq318+T2j4+PU7giVpO8ZffrkDFwqaoKjJw@mail.gmail.com>
On Mon, Oct 19, 2026 at 02:13:04PM +0530, Pranjal Kumar Singh wrote:
> Hello Security Team,
>
> The IPv4 part of this was fixed some time ago in commit 6785011f8b16
> ("ipv4: validate checksum_start before completing checksum"): a packet
> whose virtio_net_hdr csum metadata points its checksum start inside the
> IP header makes skb_checksum_help() (the deferred csum completion)
> rewrite the header the stack has already validated (fixed checksum
> offset-width write at csum_start + csum_offset). The IPv6 paths were
> not covered, and they still are not: a 2-patch series mirroring that
> commit for IPv4->IPv6, including its remaining not-yet-IPv6-guarded
> sinks, is reproduced below and attached as patches/0001 and 0002.
Thanks, I think this has been reported already. Just to clarify, the effect
is just packet header corruption past validation, right?
See [PATCH net-next v2 0/7] more virtio-net csum hardening
for WIP fixes.
--
MST
next prev parent reply other threads:[~2026-10-19 8:50 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-19 8:43 Kernel bug report: unguarded deferred skb_checksum_help() writes corrupt the previously-validated IPv6 fixed header (IPv6 counterpart of commit 6785011f8b16, "ipv4: validate checksum_start before completing checksum") Pranjal Kumar Singh
2026-10-19 8:50 ` Michael S. Tsirkin [this message]
[not found] ` <CA+UYBZCEe3C2HuqgZSZ9Xa7MUxCNy=9ckBmA1Kyjmt882ZRQBA@mail.gmail.com>
2026-10-19 10:09 ` Michael S. Tsirkin
2026-10-19 8:54 ` Greg KH
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