From: Simon Horman <horms@kernel.org>
To: "Jérémy Jean" <Jeremy.Jean@oss.cyber.gouv.fr>
Cc: "David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] net: gue: reject invalid REMCSUM offsets
Date: Mon, 24 Aug 2026 13:27:06 +0100 [thread overview]
Message-ID: <20260824122706.GR265046@horms.kernel.org> (raw)
In-Reply-To: <20260820220210.3122690-2-Jeremy.Jean@oss.cyber.gouv.fr>
On Thu, Aug 20, 2026 at 10:02:10PM +0000, Jérémy Jean wrote:
> The REMCSUM option carries an absolute checksum start and checksum field
> offset. gue_remcsum() passes them to skb_remcsum_process(), whose
> partial path stores offset - start in the u16 skb->csum_offset. If
> offset is less than start, this underflows (for example, 1/0 becomes
> 0xffff).
>
> A forwarded packet can retain CHECKSUM_PARTIAL and reach a
> NETIF_F_HW_CSUM driver which trusts the metadata, leading
> skb_copy_and_csum_dev() to write two bytes about 64 KiB beyond the
> destination buffer.
>
> Reject reversed tuples in both normal and GRO receive paths.
>
> Fixes: fe881ef11cf0 ("gue: Use checksum partial with remote checksum offload")
> Assisted-by: Codex:gpt-5
> Signed-off-by: Jérémy Jean <Jeremy.Jean@oss.cyber.gouv.fr>
Reviewed-by: Simon Horman <horms@kernel.org>
next prev parent reply other threads:[~2026-08-24 12:27 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-20 22:02 [PATCH] net: gue: reject invalid REMCSUM offsets Jérémy Jean
2026-08-24 12:27 ` Simon Horman [this message]
2026-08-24 13:38 ` Eric Dumazet
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260824122706.GR265046@horms.kernel.org \
--to=horms@kernel.org \
--cc=Jeremy.Jean@oss.cyber.gouv.fr \
--cc=davem@davemloft.net \
--cc=edumazet@google.com \
--cc=kuba@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=pabeni@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.