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 E8D24481FDF; Tue, 4 Aug 2026 18:00:53 +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=1785866455; cv=none; b=TodLYNO5QA5b/jYyH+ZK1e9jcdqz60hQGAuVjgIFbBqm3a+2R/TFMLZJaemfrGBa0nMoJL3MLdwAzPVG5a3+DS7IO4nscsAQGMT0MB/ldue+fXCJcLqJ4Zpe+pWR+VmrmQjCzQZMfYef4yytdtKaMn3+MhH9pVWNvfjlKqkErSE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785866455; c=relaxed/simple; bh=iYbz8ptwNvphLEpaCX5NMpJJCU8tvPOhVm0UJfyvN1c=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=UOEcOTf03p04szUFsLKDhqoFJo57qiCyB3DqEIclm+1Qp8ck4jkHJL6gVSAz5f36LD+Bbyp062bdZJNp2itveJ2lKRDRCfJ7xIwUjNezCVyzGRepvF5p81VynUrdWbUId7/MXhobRJefk0uYszYOmXHKuobyDgZPNYHWwb3qPdY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=lH2Q/ph9; 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="lH2Q/ph9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 29F6A1F000E9; Tue, 4 Aug 2026 18:00:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785866453; bh=Ol4u73S6iewdfvEZtCXNgbQ1k86m1sgo4EC26jm0nDs=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=lH2Q/ph9dte98Ehh3x/G9+ZuCkl9gy7qofZqnmouUTacoGXpTDkAJ06Wrpp5/PzRF 5amPgP7rnoYCm30u45mG8J7HEyiLUkTnzKkNDOxaxBsXG+5xbzB0W41er6rkvG7i8W JBQOnms5HzDkBdRtij1ILtJNNnzf5jHCT27rvTXgaA/jWuRHeXA3CjBbneYp7WNoIh taLVGOoBhR8TjXUn3xxyVoMlqpaWZP0Z5CRgQwnP9Fhw/mNO63vruTWi52wMU25HNx Jsn+buyNdmKCKk2dt1jnr3VX7KcRVfsXhTG3pfrBurvr1wVPpHl6f+5VlgWHziUB2x qB/r6ihDMk8Xw== Message-ID: Date: Tue, 4 Aug 2026 20:00:43 +0200 Precedence: bulk X-Mailing-List: linux-kernel@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: David Lee , Kyle Zeng 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 , yuantan098@gmail.com, yifanwucs@gmail.com, tomapufckgml@gmail.com, bird@lzu.edu.cn, caoruide123@gmail.com, enjou1224z@gmail.com, Ren Wei , yuantan098@gmail.com, 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: 7bit 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? One last thing: it looks like your patch is conflicting with this one: https://lore.kernel.org/netdev/20260803061739.134737-1-jiayuan.chen@linux.dev/ > Cc: stable@vger.kernel.org > Assisted-by: Codex:gpt-5.6-sol Codex:gpt-5.5-cyber > Signed-off-by: Kyle Zeng > Co-developed-by: David Lee > Signed-off-by: David Lee > --- > Bug found and triaged by OpenAI Security Research and > validated by Trail of Bits. > > Trail of Bits has a reproducer for this bug that triggers a > KASAN use-after-free and can share if needed. I think it would be good to include the (decoded) KASAN warning in the commit message. Regarding the reproducer, if it is with packetdrill, I think it is always useful to share it. For others, don't hesitate to share it to the same people: it can help better understanding the issue. Maybe remove the mailing list when doing that if it is security related? Cheers, Matt -- Sponsored by the NGI0 Core fund.