From nobody Sun Dec 14 06:36:32 2025 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 8606D2FB08F; Wed, 3 Dec 2025 13:32:00 +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=1764768720; cv=none; b=BG10rBmUY2LNXkCjD7VLAf3IQWjn4UOiOInbVTaIenLmUYyjdOiAOUISb/c5CPN7gHy9VyrD35itf+B2Grn8BBAvpIv52jC4VP1sorcdwB1Hq4X1avy9370ZX3D3wipKLDhKGKf5PDDutn5kGy8kZ7I8iusY13mXMf9NdGdp2CQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764768720; c=relaxed/simple; bh=uXJDv15SsCAdhA6on8Kcs6NSuijMkmM3ly31Esed8w8=; h=Subject:To:Cc:From:Date:In-Reply-To:Message-ID:MIME-Version: Content-Type; b=Fxi75mrwyEoy+UdAZcGPQKCcsBc4OU/Dg4zSEwY1KsPVXSS7LbWq5D+Vp9MbzGWv24bZ1fORrs4hhWK+R1Mar4iuasewUMYjJy3vPLN6XdwM10q3l/IN38G5KFrcJtdUPTQbCVaTwmz34Nf0zwHbl+keNymdXu1XeOMcTdQB7VE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=WqEVLmrd; 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="WqEVLmrd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 75970C4CEFB; Wed, 3 Dec 2025 13:31:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1764768720; bh=uXJDv15SsCAdhA6on8Kcs6NSuijMkmM3ly31Esed8w8=; h=Subject:To:Cc:From:Date:In-Reply-To:From; b=WqEVLmrdQCyO7ZJbbM3yIC1HE8YIUgI9s1mZCqs5iXQlyobWisqKgTndsdPjV/SPG usl2F60tpGy5VLtIJOKSmXJDeybj+rswdEyUPmZ5xyB0DqYqUhmYq9E8mmt3DPLbJD /IFU7Q+BxgEB8H9AMHAlV4zaMKDqF93zeG6w4rwU= Subject: Patch "mptcp: Fix proto fallback detection with BPF" has been added to the 5.15-stable tree To: gregkh@linuxfoundation.org,jakub@cloudflare.com,jiayuan.chen@linux.dev,martin.lau@kernel.org,matttbe@kernel.org,mptcp@lists.linux.dev Cc: From: Date: Wed, 03 Dec 2025 14:31:37 +0100 In-Reply-To: <20251201112712.3573321-2-matttbe@kernel.org> Message-ID: <2025120337-shakable-coastline-aea3@gregkh> Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-stable: commit X-Patchwork-Hint: ignore Content-Type: text/plain; charset="utf-8" This is a note to let you know that I've just added the patch titled mptcp: Fix proto fallback detection with BPF to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=3Dlinux/kernel/git/stable/stable-queue.git= ;a=3Dsummary The filename of the patch is: mptcp-fix-proto-fallback-detection-with-bpf.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. From stable+bounces-197759-greg=3Dkroah.com@vger.kernel.org Mon Dec 1 12:3= 1:55 2025 From: "Matthieu Baerts (NGI0)" Date: Mon, 1 Dec 2025 12:27:13 +0100 Subject: mptcp: Fix proto fallback detection with BPF To: stable@vger.kernel.org, gregkh@linuxfoundation.org Cc: MPTCP Upstream , Jiayuan Chen , Martin KaFai Lau , Jakub Sitnicki , "Matthieu Baerts (NGI0)" Message-ID: <20251201112712.3573321-2-matttbe@kernel.org> From: Jiayuan Chen commit c77b3b79a92e3345aa1ee296180d1af4e7031f8f upstream. The sockmap feature allows bpf syscall from userspace, or based on bpf sockops, replacing the sk_prot of sockets during protocol stack processing with sockmap's custom read/write interfaces. ''' tcp_rcv_state_process() syn_recv_sock()/subflow_syn_recv_sock() tcp_init_transfer(BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB) bpf_skops_established <=3D=3D sockops bpf_sock_map_update(sk) <=3D=3D call bpf helper tcp_bpf_update_proto() <=3D=3D update sk_prot ''' When the server has MPTCP enabled but the client sends a TCP SYN without MPTCP, subflow_syn_recv_sock() performs a fallback on the subflow, replacing the subflow sk's sk_prot with the native sk_prot. ''' subflow_syn_recv_sock() subflow_ulp_fallback() subflow_drop_ctx() mptcp_subflow_ops_undo_override() ''' Then, this subflow can be normally used by sockmap, which replaces the native sk_prot with sockmap's custom sk_prot. The issue occurs when the user executes accept::mptcp_stream_accept::mptcp_fallback_tcp_ops(). Here, it uses sk->sk_prot to compare with the native sk_prot, but this is incorrect when sockmap is used, as we may incorrectly set sk->sk_socket->ops. This fix uses the more generic sk_family for the comparison instead. Additionally, this also prevents a WARNING from occurring: result from ./scripts/decode_stacktrace.sh: Reviewed-by: Jakub Sitnicki Reviewed-by: Matthieu Baerts (NGI0) ------------[ cut here ]------------ WARNING: CPU: 0 PID: 337 at net/mptcp/protocol.c:68 mptcp_stream_accept \ (net/mptcp/protocol.c:4005) Modules linked in: ... PKRU: 55555554 Call Trace: do_accept (net/socket.c:1989) __sys_accept4 (net/socket.c:2028 net/socket.c:2057) __x64_sys_accept (net/socket.c:2067) x64_sys_call (arch/x86/entry/syscall_64.c:41) do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:9= 4) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) RIP: 0033:0x7f87ac92b83d ---[ end trace 0000000000000000 ]--- Fixes: 0b4f33def7bb ("mptcp: fix tcp fallback crash") Signed-off-by: Jiayuan Chen Signed-off-by: Martin KaFai Lau Reviewed-by: Jakub Sitnicki Reviewed-by: Matthieu Baerts (NGI0) Cc: Link: https://patch.msgid.link/20251111060307.194196-3-jiayuan.chen@linux.d= ev [ Conflicts in protocol.c, because commit 8e2b8a9fa512 ("mptcp: don't overwrite sock_ops in mptcp_is_tcpsk()") is not in this version. It changes the logic on how and where the sock_ops is overridden in case of passive fallback. To fix this, mptcp_is_tcpsk() is modified to use the family, but first, a check of the protocol is required to continue returning 'false' in case of MPTCP socket. ] Signed-off-by: Matthieu Baerts (NGI0) Signed-off-by: Greg Kroah-Hartman --- net/mptcp/protocol.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -77,8 +77,13 @@ static u64 mptcp_wnd_end(const struct mp static bool mptcp_is_tcpsk(struct sock *sk) { struct socket *sock =3D sk->sk_socket; + unsigned short family; =20 - if (unlikely(sk->sk_prot =3D=3D &tcp_prot)) { + if (likely(sk->sk_protocol =3D=3D IPPROTO_MPTCP)) + return false; + + family =3D READ_ONCE(sk->sk_family); + if (unlikely(family =3D=3D AF_INET)) { /* we are being invoked after mptcp_accept() has * accepted a non-mp-capable flow: sk is a tcp_sk, * not an mptcp one. @@ -89,7 +94,7 @@ static bool mptcp_is_tcpsk(struct sock * sock->ops =3D &inet_stream_ops; return true; #if IS_ENABLED(CONFIG_MPTCP_IPV6) - } else if (unlikely(sk->sk_prot =3D=3D &tcpv6_prot)) { + } else if (unlikely(family =3D=3D AF_INET6)) { sock->ops =3D &inet6_stream_ops; return true; #endif Patches currently in stable-queue which might be from matttbe@kernel.org are queue-5.15/x86-boot-compile-boot-code-with-std-gnu11-too.patch queue-5.15/mptcp-disallow-mptcp-subflows-from-sockmap.patch queue-5.15/revert-docs-process-howto-replace-c89-with-c11.patch queue-5.15/mptcp-fix-race-condition-in-mptcp_schedule_work.patch queue-5.15/mptcp-restore-window-probe.patch queue-5.15/mptcp-fix-proto-fallback-detection-with-bpf.patch queue-5.15/mptcp-do-not-fallback-when-ooo-is-present.patch queue-5.15/arch-back-to-std-gnu89-in-v5.18.patch queue-5.15/selftests-mptcp-join-rm-set-backup-flag.patch queue-5.15/selftests-mptcp-connect-fix-fallback-note-due-to-ooo.patch queue-5.15/mptcp-fix-ack-generation-for-fallback-msk.patch queue-5.15/mptcp-pm-in-kernel-c-flag-handle-late-add_addr.patch queue-5.15/mptcp-fix-premature-close-in-case-of-fallback.patch queue-5.15/mptcp-fix-a-race-in-mptcp_pm_del_add_timer.patch queue-5.15/gcov-add-support-for-gcc-15.patch queue-5.15/mptcp-avoid-unneeded-subflow-level-drops.patch