From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E9FD941F5EE; Wed, 5 Aug 2026 10:34:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785926100; cv=none; b=HFcoG1tYQaJM5fHy2aeSekWRQXvknWz+v5n9xkDmIVN89LZ71PPPifj5IeQy/UjjIK1kqXdzQBHjsZAPPsi+Yzbj2E5jAllTnL99pYBpvrqMMkL+kHh/dW1IvEERs0kuFKmxmx2sH0uMKddaOiVeloyKuRRKrt94MKlkXQn88BU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785926100; c=relaxed/simple; bh=6yhnC/JB9zpHR98EjGt6/BBOLbeswDUkp+NkaIi6r5Y=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=gCvHhltcbpP+gHsMqebwyxWGx6VRZeDZju41JtC5mVP9wVYDuIdQyOW0X/ncQgaNnxjG5qe+Wl1KDr+l0sPENjhuFDUKNoiGw3fxX0y3JA6cD+l2vDgVFFAXqsEQ2+1YrU3F+lvDjgSVEAfzBXZgtjgUU10ubdiJiM9Zji3RZEM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ab1fxJ66; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ab1fxJ66" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2B8631F000E9; Wed, 5 Aug 2026 10:34:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785926091; bh=fJaUVTxoVSLFYtIDACf5QAyWVCuC9LHzgmitQoJw2UY=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=ab1fxJ66dgNjk8KUt7iazikxK9rs4TvkYuICwdUVa9V1VaMpVQWvxIwHvui4kW0sk mvHX9hSeJFvi+3vuUsWEbREAVDuDEAGHm7U3anF8pxMNLuhP/5OAuuL+n03R0DRtGG jayja7GKqvWX0/01+bYJCnls0h38hKkL5swvZocp33awSbQB7KmifLhDdgFeOx7Hpf uUPmb+49CXZf4AttmQQfDsoXAPEnPy0qU8POfhN/fWr2efvE8EZe/gLMSPp79+dUwb eKJbV0mPaQgVOn28odlif0G9VJBLZ2qBZHx42G/ad7s0PLt6AWyHV6qbbAzoNGz/L7 qGcJdxVy3wEXA== Message-ID: <57e21541-ba97-42f7-9b93-29d443ff1fd3@kernel.org> Date: Wed, 5 Aug 2026 12:34:43 +0200 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [PATCH net] mptcp: hold msk reference when cloning request sockets Content-Language: fr To: Yuan Tan , Kyle Zeng , David Lee Cc: Dominik 'Disconnect3d' Czarnota , geliang@kernel.org, horms@kernel.org, kuniyu@google.com, netdev@vger.kernel.org, mptcp@lists.linux.dev, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Ren Wei , yifanwucs@gmail.com, tomapufckgml@gmail.com, bird@lzu.edu.cn, caoruide123@gmail.com, enjou1224z@gmail.com, Vega , martineau@kernel.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, ncardwell@google.com References: <20260804095051.715355-1-david.lee@trailofbits.com> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit Hi Yuan, Thank you for your reply. On 05/08/2026 10:52, Yuan Tan wrote: > On Tue, Aug 4, 2026 at 11:00 AM Matthieu Baerts wrote: >> >> Hi David, Kyle, >> >> (+cc Vega's people) >> >> On 04/08/2026 11:50, David Lee wrote: >>> From: Kyle Zeng >>> >>> An MP_JOIN request owns the reference stored in subflow_req->msk. >>> inet_reqsk_clone() byte-copies that pointer when migrating a request, >>> but does not acquire a reference for the clone. The original and cloned >>> request destructors can consequently drop the same reference, leaving >>> one request with a dangling msk pointer. >>> >>> Let cloned MPTCP requests take their own msk reference. The source >>> request still owns its reference while it is being cloned, so sock_hold() >>> is safe. The clone's normal destructor balances the new reference on >>> both successful and failed migration paths. >>> >>> Fixes: c905dee62232 ("tcp: Migrate TCP_NEW_SYN_RECV requests at retransmitting SYN+ACKs.") >> >> Thank you for this patch. It looks like it is similar to this one sent a >> few months ago, but where changes have been requested: >> >> https://lore.kernel.org/40fd38e7a368e5b7bc9bc83364a32241f977d53f.1778404619.git.caoruide123@gmail.com >> >> Do you mind checking what they did, and explaining the different approach, please? >> >> It seems there are two issues the Vega's team tried to solve: one with >> MP_JOIN requests (what you are trying to fix here) and with MP_CAPABLE. >> For me, it is fine to split that in two patches. I also don't mind who >> is writing the final patch(es), as long as credits are given. If you, >> David/Kyle, are doing that, it might be OK to add a: >> >> Reported-by: Vega >> Closes: https://lore.kernel.org/40fd38e7a368e5b7bc9bc83364a32241f977d53f.1778404619.git.caoruide123@gmail.com >> >> @Vega's team: OK with that? Or are you actively working on a v3? > > We seem to have lost track of this patch, and we sincerely apologize. > > Our patch addresses two issues: one involving MP_JOIN requests and the > other involving MP_CAPABLE. > > I reviewed Kyle and David’s fix for the MP_JOIN issue, and it looks > reasonable to me. Please note that Clashiko reported an issue. A new version *might* be required: https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260804095051.715355-1-david.lee%40trailofbits.com Note that both Clashiko and Sashiko are mentioning the other existing issue with MP_CAPABLE, that the Vega's team tried to fix in their v2: https://sashiko.dev/#/patchset/20260804095051.715355-1-david.lee%40trailofbits.com I think the fix can be done in two parts. > Ruide and I also do not have a preference regarding whose patch is accepted. > > If David/Kyle' patch is accepted, please add: > > Reported-by: Vega > Reported-by: Ruide Cao > Closes: https://lore.kernel.org/40fd38e7a368e5b7bc9bc83364a32241f977d53f.1778404619.git.caoruide123@gmail.com If a new version is required, please sync on who is doing what. Let's wait for Kyle and David's reply. (In case of "timeout" (after a few days), feel free to work on the v3.) Cheers, Matt -- Sponsored by the NGI0 Core fund.