Netdev List
 help / color / mirror / Atom feed
From: Paolo Abeni <pabeni@redhat.com>
To: Sanghyun Park <sanghyun.park.cnu@gmail.com>, netdev@vger.kernel.org
Cc: Andrew Lunn <andrew+netdev@lunn.ch>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>,
	David Stevens <dlstevens@us.ibm.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH net] vxlan: use one headroom snapshot for neighbour replies
Date: Tue, 1 Sep 2026 12:10:32 +0200	[thread overview]
Message-ID: <53a67f9a-b8a0-4967-b2c6-be4ee3a09735@redhat.com> (raw)
In-Reply-To: <20260831054614.2069896-2-sanghyun.park.cnu@gmail.com>

On 8/31/26 7:46 AM, Sanghyun Park wrote:
> vxlan_na_create() samples LL_RESERVED_SPACE() to size the reply skb and then
> samples it again to reserve headroom. A concurrent vxlan_changelink() can
> update needed_headroom between the two reads, creating a TOCTOU race. The
> second value can exceed the allocation and make the Ethernet header write out
> of bounds.
> 
> Snapshot the headroom once and use that value for both allocation and
> reservation.
> 
> Fixes: 4b29dba9c085 ("vxlan: fix nonfunctional neigh_reduce()")
> Signed-off-by: Sanghyun Park <sanghyun.park.cnu@gmail.com>
The patch LGTM, but the changelog needs some improvements: if you have
can observe a splat on the unpatched kernel, please include it,
otherwise please explain whythe issue is not just a theoretical one.
Also please specify if some LLM has been used.

Thanks,

Paolo


  reply	other threads:[~2026-09-01 10:10 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-08-31  5:46 [PATCH net] vxlan: use one headroom snapshot for neighbour replies Sanghyun Park
2026-09-01 10:10 ` Paolo Abeni [this message]
2026-09-02  6:59   ` Sanghyun Park

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=53a67f9a-b8a0-4967-b2c6-be4ee3a09735@redhat.com \
    --to=pabeni@redhat.com \
    --cc=andrew+netdev@lunn.ch \
    --cc=davem@davemloft.net \
    --cc=dlstevens@us.ibm.com \
    --cc=edumazet@google.com \
    --cc=kuba@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --cc=sanghyun.park.cnu@gmail.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox