From: Jakub Kicinski <kuba@kernel.org>
To: Michael Bommarito <michael.bommarito@gmail.com>
Cc: Taehee Yoo <ap420073@gmail.com>,
"David S . Miller" <davem@davemloft.net>,
Paolo Abeni <pabeni@redhat.com>,
Eric Dumazet <edumazet@google.com>,
Andrew Lunn <andrew+netdev@lunn.ch>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH net v2] amt: don't read the IP source address from a reallocated skb header
Date: Sun, 21 Jun 2026 15:00:11 -0700 [thread overview]
Message-ID: <20260621150011.33c2fe80@kernel.org> (raw)
In-Reply-To: <20260617123443.3586930-1-michael.bommarito@gmail.com>
On Wed, 17 Jun 2026 08:34:43 -0400 Michael Bommarito wrote:
> amt_update_handler() caches iph = ip_hdr(skb) and then calls
> pskb_may_pull(). pskb_may_pull() can reallocate the skb head: the new
> head is allocated and the old one is freed. The cached iph is not
> refreshed, so the following tunnel lookup reads iph->saddr from the
> freed head. On an AMT relay this lookup runs for every incoming
> membership update, before the update's nonce and response MAC are
> validated.
>
> The sibling handlers amt_multicast_data_handler() and
> amt_membership_query_handler() re-read ip_hdr() after the pull and are
> not affected; only amt_update_handler() keeps the pre-pull pointer.
Sashikos point out a bunch more of these in AMT:
https://sashiko.dev/#/patchset/20260617123443.3586930-1-michael.bommarito@gmail.com
https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260617123443.3586930-1-michael.bommarito@gmail.com
Let's fix them all with one patch?
--
pw-bot: cr
prev parent reply other threads:[~2026-06-21 22:00 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-17 12:34 [PATCH net v2] amt: don't read the IP source address from a reallocated skb header Michael Bommarito
2026-06-21 22:00 ` Jakub Kicinski [this message]
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