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From: Florian Westphal <fw@strlen.de>
To: Fernando Fernandez Mancera <fmancera@suse.de>
Cc: netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
	pablo@netfilter.org, phil@nwl.cc
Subject: Re: [PATCH 4/4 nf v2] netfilter: synproxy: fix possible write to stale pointer
Date: Tue, 26 May 2026 15:05:57 +0200	[thread overview]
Message-ID: <ahWatXyiNiBrE9FX@strlen.de> (raw)
In-Reply-To: <4887bf00-d044-4366-8588-a83e4bce0274@suse.de>

Fernando Fernandez Mancera <fmancera@suse.de> wrote:
> > In particular, seqadj and concurrent registration.  As these bugs aren't
> > as severe as patch 4, I think nf-next would be fine as well.
> > 
> > 
> 
> I have been taking a look to this. The seqadj issue isn't real IMHO.

We could be processing a 2nd packet in parallel, in particular reply
direction is a concern.

> The logic here is protected by the TCP state machine. AFAIU, ALGs only 
> look at fully established connections, I don't see how this can happen 
> even for retransmitted packets, the TCP state would remain the same so 
> nf_ct_seqadj_init() should never race with nf_ct_seqadj_set().

Can't we race with nf_ct_seq_adjust(), e.g. for closed state when
connection is reopened?

> FWIW; the concurrent registration issue is real. I am writing a fix.

Thanks.

  reply	other threads:[~2026-05-26 13:06 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-05-25 12:44 [PATCH 0/4 nf v2] netfilter: synproxy: timestamp adjustment fixes Fernando Fernandez Mancera
2026-05-25 12:44 ` [PATCH 1/4 nf v2] netfilter: synproxy: drop packets if timestamp adjustment fails Fernando Fernandez Mancera
2026-05-25 12:44 ` [PATCH 2/4 nf v2] netfilter: synproxy: adjust duplicate timestamp options Fernando Fernandez Mancera
2026-05-25 12:44 ` [PATCH 3/4 nf v2] netfilter: synproxy: fix unaligned memory access in timestamp adjustment Fernando Fernandez Mancera
2026-05-25 12:44 ` [PATCH 4/4 nf v2] netfilter: synproxy: fix possible write to stale pointer Fernando Fernandez Mancera
2026-05-25 13:45   ` Fernando Fernandez Mancera
2026-05-25 18:59     ` Florian Westphal
2026-05-25 19:02       ` Fernando Fernandez Mancera
2026-05-26 10:12       ` Fernando Fernandez Mancera
2026-05-26 13:05         ` Florian Westphal [this message]
2026-05-26 13:12           ` Fernando Fernandez Mancera

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