From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 56909679E1 for ; Tue, 30 Jan 2024 11:59:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706615996; cv=none; b=l+KVhEDLjD6/fvs32sEoHSJRjJUsWfQVrGgi2ZQDqE960sr6NER8OpJ25HC23slUXGVT7IEL4sqsPV5y1dgGZVQn+WMlIEqVyJyUkcJd81U01UjXyC83frKkjswKLvn7nLy8XGfvuIuCBz2CupAkVzu4j52rCiWE/T6ZCLjqHlM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706615996; c=relaxed/simple; bh=8r2/KbsEwLQFFXWCMvjcirM7mtvKvinGsBcE5VaeylY=; h=Message-ID:Date:MIME-Version:Subject:To:References:From: In-Reply-To:Content-Type; b=l6La3NDHbkgPHlwTRKJpo+v4y8IwdgYD0C9HIYBXOhcAwdKOeH8pulXmw2h/y+hKLKuRnrK5Hz/gM9TgKSO18VPlBznQqFuTaZphU8rwqhFLVSR3p1b/oXZhVbAM+aMgGTv2MSZA9QIT2y5aFbW9Qn5+cQ5RxiODrQBnE/YwhaM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=vOhfac8q; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="vOhfac8q" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 506B8C433C7; Tue, 30 Jan 2024 11:59:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1706615995; bh=8r2/KbsEwLQFFXWCMvjcirM7mtvKvinGsBcE5VaeylY=; h=Date:Subject:To:References:From:In-Reply-To:From; b=vOhfac8qmjPtdhwb+TANPJcodABVG4+pyJaFh8AEYMjUznM7qdFyGG3fCsBTVOr8z 4RNFcWkTLtpSbyTHMxpAI3MuPQh0R8mh2fdyVWkvmtnXF8JR3rRFmsi8ckmFnZHcXb w42pm7RQrCAKXfKqvW6v/lfir9uqKY9sQia3TrtdxnzpFwd/tJs5bq9X6S1WDX4+PS Nn6GfSldipa6zY20nIc+oulE/Vlqi9ISBKJ/V9EI7JmZA3wHRNKIRMWli5qO+kxj3p PMmijjaZ7T/dxOzxU0uSVRv8lSqL4bvGlSV7HpKPXbXKGuq9Aebbi+NyO/NUeSdlWS BnyVziyeOCv5Q== Message-ID: <39a0fa5f-03e2-4ef3-90b7-decd8971905b@kernel.org> Date: Tue, 30 Jan 2024 12:59:53 +0100 Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH mptcp-net] mptcp: fix data re-injection from stale subflow To: Paolo Abeni , mptcp@lists.linux.dev References: <35875ef9cb7194563b580e14c71cc8cb065f846c.1706043786.git.pabeni@redhat.com> Content-Language: en-GB, fr-BE From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Paolo, Mat, On 23/01/2024 22:03, Paolo Abeni wrote: > When the MPTCP PM detects that a subflow is stale, all the packet > scheduler must re-inject all the mptcp-level unacked data. To avoid > acquiring unneeded locks, it first try to check if any unacked data > is present at all in the RTX queue, but such check is currently > broken, as it uses TCP-specific helper on an MPTCP socket. > > Funnily enough fuzzers and static checkers are happy, as the accessed > memory still belongs to the mptcp_sock struct, and even from a > functional perspective the recovery completed successfully, as > the short-cut test always failed. > > A recent unrelated TCP change - commit d5fed5addb2b ("tcp: reorganize > tcp_sock fast path variables") - exposed the issue, as the tcp field > reorganization makes the mptcp code always skip the re-inection. > > Fix the issue dropping the bogus call: we are on a slow path, the early > optimization proved once again to be evil. > > Fixes: 1e1d9d6f119c ("mptcp: handle pending data on closed subflow") > Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/468 > Signed-off-by: Paolo Abeni Thank you for the patch and the review! Any ideas how to prevent such issues? Changing the signature of the TCP-specific functions? Adding a custom check for our CI on our side? New patches for t/upstream-net and t/upstream: - 359966180a29: mptcp: fix data re-injection from stale subflow - Results: d2cf5db9b409..ca82f8ccb3cc (export-net) - Results: 171302925a80..4b8f1ec22243 (export) Tests are now in progress: https://cirrus-ci.com/github/multipath-tcp/mptcp_net-next/export-net/20240130T115340 https://cirrus-ci.com/github/multipath-tcp/mptcp_net-next/export/20240130T115340 Cheers, Matt -- Sponsored by the NGI0 Core fund.