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 94CF54B3382 for ; Thu, 3 Sep 2026 14:13:06 +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=1788444798; cv=none; b=ZjdJNCahyVfrFDi8KP6dj3OiRre0mTDM+Zljk1fKE0EQsGdKm1YWUHAyo51sPGTF1IVREnyI866ClInQMIGkiU/fDaBmmN5PnHzJAvXKmMMCx6PWE9ojPo4g8ahzcNCJBrnLmyka80UTzKDe+wwtK8rNRH46hnmQiRPv3wWaisk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788444798; c=relaxed/simple; bh=zLyKl17DAY502ydfq09Rvs+jvptSVtnuRH4ltx1yX2E=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=GPXqjCPAiYlKcxGyVnwau1p+Y+42FZXwwll3c9/Nfw8vhjkiw1ls4CcQ5IUrg2TE/MMUvHi65L/P9TqAB59AXrIYqEtcgcKDnbt1pKXzGMDlvOW4hS7jYKp2/GGj+LD9ZQwWdGUiYDtKTcBuNJ03ckDJVCEARaLyX8NXb3uxA8A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=CyNMEsjq; 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="CyNMEsjq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 519881F00A3A; Thu, 3 Sep 2026 14:13:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788444784; bh=ACw6fPO7Q3c0UtFXLT3zNNHxZu+s6UpYc9EkqyC982Q=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=CyNMEsjq+Hlu1CtR74gsAd90X9ByPjRKXxNbBL0zjKK9mcGTp15MaLkjsGq7CKCxy ehrMAMgSOe2vrg5n+Qbp1UhI7nqWhF/CWqtZzNxmHYn5YZwsD1msuoLhH5Wli0Txay +1HPvl7Z0HwMRc/ZDgdQW9bsUESQDuPiROZTqZdMO1ZKjl2ZJ5765zh4I7F+EsTm7E DEElmTGMuOeziVGIPe7fe9f9LCCK7pBgEiaSCdy4yiltfpzrfFBdkC9EgeP1azHQt6 hHV82R8H/dfhYbWVPwv8m2uumxsxSyJRJ35gzfkd68uMD0Kb9G9FgFneODbFQ+cBm2 P1QwKQMVjhwGw== Message-ID: Date: Thu, 3 Sep 2026 16:13:01 +0200 Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [PATCH mptcp-next v2 3/3] mptcp: pm: userspace: cap extra_subflows on Netlink subflow creation Content-Language: fr To: Tao Cui , mptcp@lists.linux.dev, quanyeyang@proton.me Cc: geliang@kernel.org, cuitao@kylinos.cn References: <20260903131416.1112393-1-cui.tao@linux.dev> <20260903131416.1112393-4-cui.tao@linux.dev> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Tao, Quanye, On 03/09/2026 15:14, Tao Cui wrote: > From: Quanye Yang > > mptcp_pm_nl_subflow_create_doit() also increments the u8 extra_subflows > counter without any limit: a client with CAP_NET_ADMIN can create more > than 255 extra subflows via Netlink and wrap the counter back to 0, > with the same effects as the MP_JOIN path now bounded separately: > the underflow guards warn on the next subflow close, and > mptcpi_subflows_total reported to userspace is corrupted. > > Refuse the subflow creation with -ENOSPC once the counter has reached > U8_MAX, and clean up the local address entry in that case as well. > > Fixes: 77e4b94a3de6 ("mptcp: update userspace pm infos") > Link: https://lore.kernel.org/all/20260902-mptcp-pm-extra-subflows-v1-1-68540a866e5a@proton.me/ > Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/629 > (no empty line here) > Signed-off-by: Quanye Yang > Signed-off-by: Tao Cui > --- > net/mptcp/pm_userspace.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/net/mptcp/pm_userspace.c b/net/mptcp/pm_userspace.c > index b94fbb483bf9..3371e17d01b9 100644 > --- a/net/mptcp/pm_userspace.c > +++ b/net/mptcp/pm_userspace.c > @@ -417,6 +417,12 @@ int mptcp_pm_nl_subflow_create_doit(struct sk_buff *skb, struct genl_info *info) > local.ifindex = entry.ifindex; > > spin_lock_bh(&msk->pm.lock); > + if (msk->pm.extra_subflows == U8_MAX) { > + spin_unlock_bh(&msk->pm.lock); > + GENL_SET_ERR_MSG(info, "too many extra subflows"); > + err = -ENOSPC; > + goto delete_addr; > + } > msk->pm.extra_subflows++; > spin_unlock_bh(&msk->pm.lock); > > @@ -424,9 +430,11 @@ int mptcp_pm_nl_subflow_create_doit(struct sk_buff *skb, struct genl_info *info) > err = __mptcp_subflow_connect(sk, &local, &addr_r); > release_sock(sk); > > - if (err) { > + if (err) > GENL_SET_ERR_MSG_FMT(info, "connect error: %d", err); > > +delete_addr: Can you not have the label inside the if-statement? if (err) { GENL_SET_ERR_MSG_FMT(info, "connect error: %d", err); delete_addr: (...) > + if (err) { > spin_lock_bh(&msk->pm.lock); > mptcp_userspace_pm_delete_local_addr(msk, &entry); Maybe you can add something in the commit message for the reviewers: The same error path is followed after mptcp_userspace_pm_append_new_local_addr, which should probably not delete the local address unconditionally, but this is a pre-existing issue that will be addressed separately. > spin_unlock_bh(&msk->pm.lock); Cheers, Matt -- Sponsored by the NGI0 Core fund.