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 48305326D57; Mon, 27 Oct 2025 19:28:58 +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=1761593338; cv=none; b=iELCCzygbjWdwM/FtLcwnielEGRfCJhfrmcGuJNjivty6xV/Dd0vZ0o3Rr9ROVQHLRPxjTEYvbnnIJx4fAm29ZfFxeldIMoNQwqCNqX1AokvEbT/gLsJ5AqDkcMcTMMpz8wO9o5zk32wi6R8/nK5CcaWjTpCW61fzeyJj7XzpmA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761593338; c=relaxed/simple; bh=1U87pk044WuEdTOTzcEjZa5STFnA39Ci48CVt3ZOmrg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Un9gsCdCzf+m61UTnlNK5wghfELsfY+sZJ1jyPDkBHbr8V/3B/QoDDzUvYE+l0G/CUlO8mnVuaOLDRTPD7cYYWRvXY43lQolc0C55+/woeQ0HWqChDEbx901N7XGvGOFhjtSkUeIaQT49ZitAjM7GkYET1ZLktfZQmelSC6zgLs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=qAyD4wx4; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="qAyD4wx4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BCA23C4CEFD; Mon, 27 Oct 2025 19:28:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1761593338; bh=1U87pk044WuEdTOTzcEjZa5STFnA39Ci48CVt3ZOmrg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qAyD4wx4+TpsMm+YsBw2pRjOrBDV1e5dvemVygMiJiJJdiJbvAoi7J//x4uXilHtD n1hb6n2Pdjv+fwFi6hrgUjUeEUzl3lnFbs7oiDMTfUtrkUifAL4wiQa5xUs4pPi2ej Ks2bwqfLBFSfaQROqb98/3rmCHgSP/f5fFrcrS3U= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Geliang Tang , "Matthieu Baerts (NGI0)" , Jakub Kicinski Subject: [PATCH 6.17 101/184] mptcp: pm: in-kernel: C-flag: handle late ADD_ADDR Date: Mon, 27 Oct 2025 19:36:23 +0100 Message-ID: <20251027183517.632948550@linuxfoundation.org> X-Mailer: git-send-email 2.51.1 In-Reply-To: <20251027183514.934710872@linuxfoundation.org> References: <20251027183514.934710872@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.17-stable review patch. If anyone has any objections, please let me know. ------------------ From: Matthieu Baerts (NGI0) commit e84cb860ac3ce67ec6ecc364433fd5b412c448bc upstream. The special C-flag case expects the ADD_ADDR to be received when switching to 'fully-established'. But for various reasons, the ADD_ADDR could be sent after the "4th ACK", and the special case doesn't work. On NIPA, the new test validating this special case for the C-flag failed a few times, e.g. 102 default limits, server deny join id 0 syn rx [FAIL] got 0 JOIN[s] syn rx expected 2 Server ns stats (...) MPTcpExtAddAddrTx 1 MPTcpExtEchoAdd 1 Client ns stats (...) MPTcpExtAddAddr 1 MPTcpExtEchoAddTx 1 synack rx [FAIL] got 0 JOIN[s] synack rx expected 2 ack rx [FAIL] got 0 JOIN[s] ack rx expected 2 join Rx [FAIL] see above syn tx [FAIL] got 0 JOIN[s] syn tx expected 2 join Tx [FAIL] see above I had a suspicion about what the issue could be: the ADD_ADDR might have been received after the switch to the 'fully-established' state. The issue was not easy to reproduce. The packet capture shown that the ADD_ADDR can indeed be sent with a delay, and the client would not try to establish subflows to it as expected. A simple fix is not to mark the endpoints as 'used' in the C-flag case, when looking at creating subflows to the remote initial IP address and port. In this case, there is no need to try. Note: newly added fullmesh endpoints will still continue to be used as expected, thanks to the conditions behind mptcp_pm_add_addr_c_flag_case. Fixes: 4b1ff850e0c1 ("mptcp: pm: in-kernel: usable client side with C-flag") Cc: stable@vger.kernel.org Reviewed-by: Geliang Tang Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20251020-net-mptcp-c-flag-late-add-addr-v1-1-8207030cb0e8@kernel.org Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/mptcp/pm_kernel.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/net/mptcp/pm_kernel.c +++ b/net/mptcp/pm_kernel.c @@ -333,6 +333,10 @@ static void mptcp_pm_create_subflow_or_s } subflow: + /* No need to try establishing subflows to remote id0 if not allowed */ + if (mptcp_pm_add_addr_c_flag_case(msk)) + goto exit; + /* check if should create a new subflow */ while (msk->pm.local_addr_used < local_addr_max && msk->pm.subflows < subflows_max) { @@ -364,6 +368,8 @@ subflow: __mptcp_subflow_connect(sk, &local, &addrs[i]); spin_lock_bh(&msk->pm.lock); } + +exit: mptcp_pm_nl_check_work_pending(msk); }