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From: Pavel Begunkov <asml.silence@gmail.com>
To: Mina Almasry <almasrymina@google.com>, Paolo Abeni <pabeni@redhat.com>
Cc: kuba@kernel.org, kaiyuanz@google.com, willemb@google.com,
	edumazet@google.com, sdf@fomichev.me, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, dev@openvswitch.org,
	davem@davemloft.net, horms@kernel.org, ncardwell@google.com,
	kuniyu@google.com, aconole@redhat.com, echaudro@redhat.com,
	i.maximets@ovn.org, kerneljasonxing@gmail.com,
	bobbyeshleman@gmail.com, fw@strlen.de
Subject: Re: [PATCH net v4 2/2] net: tcp: block mixing readable and unreadable frags
Date: Sat, 22 Aug 2026 11:55:22 +0100	[thread overview]
Message-ID: <f4602941-5010-42de-a59c-4caf3d60b10d@gmail.com> (raw)
In-Reply-To: <CAHS8izPid1ZBEE1PqdUZGi10KK0vPZjza-nSOP65h5Munr9bHQ@mail.gmail.com>

On 8/18/26 19:37, Mina Almasry wrote:
> On Tue, Aug 18, 2026 at 3:26 AM Paolo Abeni <pabeni@redhat.com> wrote:
...>> Note the mixing described in the second direction pre-dates this patch
>> (there was no check at all before); the incorrect predicate and the
>> forced re-segmentation are new.  Reaching this also needs a local
>> privileged setup (dmabuf TX binding plus MD5/AO or IPsec plus an ethtool
>> feature change), and in that configuration a devmem send through the copy
>> path would likely already fail in skb_copy_to_page_nocache() since the
>> iovec holds dmabuf offsets rather than user addresses, so this is stated
>> as an observation rather than a demonstrated corruption path.
> 
> Pre-existing issue I think. We indeed assume binding != NULL means the
> send is devmem and zc is set. We missed that we may not set zc if
> NETIF_F_SG is not enabled. Probably the code setting binding to

Hmm, I flagged this one, I'm going to send out the diff I attached
in the thread for v3.

-- 
Pavel Begunkov


  reply	other threads:[~2026-08-22 10:55 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-08-14 19:13 [PATCH net v4 1/2] net: core: propagate unreadable flag in skb_zerocopy Mina Almasry
2026-08-14 19:13 ` [PATCH net v4 2/2] net: tcp: block mixing readable and unreadable frags Mina Almasry
2026-08-18 10:26   ` Paolo Abeni
2026-08-18 18:37     ` Mina Almasry
2026-08-22 10:55       ` Pavel Begunkov [this message]
2026-08-18 10:25 ` [PATCH net v4 1/2] net: core: propagate unreadable flag in skb_zerocopy Paolo Abeni
2026-08-18 18:36   ` Mina Almasry
2026-08-20 20:30 ` patchwork-bot+netdevbpf
2026-08-21 16:38   ` Mina Almasry

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