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 981063E7640; Tue, 6 Oct 2026 11:59:06 +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=1791287947; cv=none; b=BCxjQ+bZv3Afld/WRXXcjnVTsKhlphxKGpG8V1+bP7qWFDAblMFJUlfa5aTar1T8BCy1ibKzAILCuTwBzfSi374xWi6PEVFi0cmqnqMTKnDHev1TLxteqDWVcJnwsMklyte9gUDwXlBeNFj28e0LwwvTXK0aGmFAhb7bzYEmupU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791287947; c=relaxed/simple; bh=H9bIcuuIXnqAtetpAeZk6HQOWbnm3Kq/l876rTSS+CM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=TSta09IobKolacdb/ljejbvlWJKpxAFfhT2OpeMbo3QB3ROZmbi8yGd7kbKkqWwRGBkuydxSyWhi4iTDF2Hf+/A/H011Z1yvg6kD+fUpApIPNciNHMM3g51iPvC19zeKJ5xYNWdc6YOrDZF2YSLpiULkJxOapkPEuyaEl6UrdpA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=iwMim50w; 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="iwMim50w" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A387A1F000FF; Tue, 6 Oct 2026 11:59:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791287946; bh=TDwArwilkib5VnP7hfeIeZkF7gcbhxu4DwDUiOv/8Ss=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=iwMim50wMjIYXRSq++iaWAAAFoVOsl+Qrb0UhG9zz2/2qp8EL65L/yf7zLaTnaUYP JY6O+zHUnfjnat8Q7ochTrkcKIlQWZpKXaBzNcL46B2V+DY/7Xojp7n53Yrm0sat05 deIaHlZtowPsK+xG1kcvPmZ7kDEa7tNMI6qevb1OC4JI4uF4Xaa2pGqCliMwMTysMM DUlQimiHSnZ6oBYAV/sl9BjVVuZQ+dJCp6EUSzBo+wvJ1/vfribunqxjvHa/m7SPXh eX2EQUCCLHw2zf+spXr+VdNHmyF6Jf5mE7k6+i61RILD++OorAqO9r5WVFYGRYheyo A8sPgxPD/nuUg== Message-ID: <97c651a1-7647-4f12-8b6b-74b949dce575@kernel.org> Date: Tue, 6 Oct 2026 13:59:02 +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: pm: in-kernel: fix C-flag endpoint accounting on family mismatch Content-Language: fr To: Yiming Qian , mptcp@lists.linux.dev Cc: martineau@kernel.org, geliang@kernel.org, netdev@vger.kernel.org, stable@vger.kernel.org, Security Officers References: <20261006114409.117190-1-yimingqian591@gmail.com> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Yiming Qian, On 06/10/2026 13:42, Yiming Qian wrote: > fill_local_addresses_vec_c_flag() clears the endpoint ID bit in > id_avail_bitmap before checking whether the endpoint's address family > matches the remote ADD_ADDR. If it does not match, the loop skips the > endpoint without incrementing local_addr_used, leaving id_avail_bitmap > and local_addr_used inconsistent. > > Removing that SUBFLOW endpoint later calls > __mark_subflow_endp_available(), which sees the cleared bit, expects > local_addr_used to be non-zero, and triggers a WARN and, with > panic_on_warn=1, a panic. > > Keep the endpoints that are skipped during this specific C-flag > iteration available by tracking them in a local bitmap passed to > select_local_address(), instead of clearing their IDs in the per-socket > bitmap. Only IDs of endpoints actually used for a subflow are now > cleared and accounted for. Thank you for the patch. Please do not Cc security@k.o on patches sent to public ML. Here the issue is "just" a WARN produced in some conditions when the user has the rights to delete MPTCP endpoints. (Please remove it from future replies.) > diff --git a/net/mptcp/pm_kernel.c b/net/mptcp/pm_kernel.c > index 1a77508132354..a5952dd0ae125 100644 > --- a/net/mptcp/pm_kernel.c > +++ b/net/mptcp/pm_kernel.c (...) > @@ -574,22 +578,28 @@ fill_local_addresses_vec_c_flag(struct mptcp_sock *msk, > u8 endp_subflow_max = mptcp_pm_get_endp_subflow_max(msk); > struct sock *sk = (struct sock *)msk; > struct mptcp_pm_local *local; > + DECLARE_BITMAP(skip, MPTCP_PM_MAX_ADDR_ID + 1); > int i = 0; > > + bitmap_zero(skip, MPTCP_PM_MAX_ADDR_ID + 1); > + > while (msk->pm.local_addr_used < endp_subflow_max) { > local = &locals[i]; > > - if (!select_local_address(pernet, msk, local)) > + if (!select_local_address(pernet, msk, skip, local)) > break; > > - __clear_bit(local->addr.id, msk->pm.id_avail_bitmap); > - > - if (!mptcp_pm_addr_families_match(sk, &local->addr, remote)) > + if (!mptcp_pm_addr_families_match(sk, &local->addr, remote)) { > + __set_bit(local->addr.id, skip); > continue; > + } > > - if (local->addr.id == msk->mpc_endpoint_id) > + if (local->addr.id == msk->mpc_endpoint_id) { > + __set_bit(local->addr.id, skip); > continue; > + } > > + __clear_bit(local->addr.id, msk->pm.id_avail_bitmap); Why is it not enough to move __clear_bit() to here? Why do you need to modify select_local_address(), etc.? Also, can you also provide a regression test as well, please? Adding a subtest in tools/testing/selftests/net/mptcp/mptcp_join.sh, e.g. in deny_join_id0_tests(), adding a new subcase using "addr_nr_ns2=-1 speed=slow run_tests (...)" to remove the subflow during the connection. Cheers, Matt -- Sponsored by the NGI0 Core fund.