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 8DB6F6BFAC; Tue, 14 May 2024 10:49:19 +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=1715683759; cv=none; b=A6NtkC/0wj76CVVhfpZ6P0Wgcjrle3tbvfVILNpQLkoB+RWC84kO6+c0bvmF/eEA41d4w6VaG8Tn2dKgM+mH4E2/PoUm/4DXHvJmGFgGz1gw6O50kd2JiaKIcO/b/U4TOzxwBdPrYElyfDFjoZK7w8NQAzwoATiG8/ksj3Q5qeI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715683759; c=relaxed/simple; bh=cLDRri+xzGMaO1HEZDEFyIMG+hCoqs6mjP6NoxCe9z4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=PKj37KiXRJihwvFgtMDPnpgm50vUb8aVwCV+QDpDT4zcf2RxJwIyXja3CmZMA4n1Hs17xY9jLWzpwitPNmBjMKO+buF8PtcpVIbP00gGPfK6OGIXVu5siLeKpigya7s9FwlG2eRBfrH7LdJMJgnQYdkrZmmJRrhM35VyG7hKaNc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=la0dXWd1; 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="la0dXWd1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6DE2CC2BD10; Tue, 14 May 2024 10:49:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1715683759; bh=cLDRri+xzGMaO1HEZDEFyIMG+hCoqs6mjP6NoxCe9z4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=la0dXWd1+T5clU20PdsV2GDDMiSQO9mAFJnucDol2T3qfEkIk3MQQAW7oJth7+B1r Axh/QZnmZYzrQ+lu+o+CdDkeR4QD8B1QFwxk9uUz82Filf0N3F555RRA0xpaeQC5j6 L/K1xK3BFT9yHFiTl+3L+sUAGcmbstvXwZHUvQcs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Christoph Paasch , Paolo Abeni , Mat Martineau , "Matthieu Baerts (NGI0)" , Jakub Kicinski Subject: [PATCH 6.8 269/336] mptcp: ensure snd_nxt is properly initialized on connect Date: Tue, 14 May 2024 12:17:53 +0200 Message-ID: <20240514101048.775591127@linuxfoundation.org> X-Mailer: git-send-email 2.45.0 In-Reply-To: <20240514101038.595152603@linuxfoundation.org> References: <20240514101038.595152603@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.8-stable review patch. If anyone has any objections, please let me know. ------------------ From: Paolo Abeni commit fb7a0d334894206ae35f023a82cad5a290fd7386 upstream. Christoph reported a splat hinting at a corrupted snd_una: WARNING: CPU: 1 PID: 38 at net/mptcp/protocol.c:1005 __mptcp_clean_una+0x4b3/0x620 net/mptcp/protocol.c:1005 Modules linked in: CPU: 1 PID: 38 Comm: kworker/1:1 Not tainted 6.9.0-rc1-gbbeac67456c9 #59 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014 Workqueue: events mptcp_worker RIP: 0010:__mptcp_clean_una+0x4b3/0x620 net/mptcp/protocol.c:1005 Code: be 06 01 00 00 bf 06 01 00 00 e8 a8 12 e7 fe e9 00 fe ff ff e8 8e 1a e7 fe 0f b7 ab 3e 02 00 00 e9 d3 fd ff ff e8 7d 1a e7 fe <0f> 0b 4c 8b bb e0 05 00 00 e9 74 fc ff ff e8 6a 1a e7 fe 0f 0b e9 RSP: 0018:ffffc9000013fd48 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffff8881029bd280 RCX: ffffffff82382fe4 RDX: ffff8881003cbd00 RSI: ffffffff823833c3 RDI: 0000000000000001 RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: fefefefefefefeff R12: ffff888138ba8000 R13: 0000000000000106 R14: ffff8881029bd908 R15: ffff888126560000 FS: 0000000000000000(0000) GS:ffff88813bd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f604a5dae38 CR3: 0000000101dac002 CR4: 0000000000170ef0 Call Trace: __mptcp_clean_una_wakeup net/mptcp/protocol.c:1055 [inline] mptcp_clean_una_wakeup net/mptcp/protocol.c:1062 [inline] __mptcp_retrans+0x7f/0x7e0 net/mptcp/protocol.c:2615 mptcp_worker+0x434/0x740 net/mptcp/protocol.c:2767 process_one_work+0x1e0/0x560 kernel/workqueue.c:3254 process_scheduled_works kernel/workqueue.c:3335 [inline] worker_thread+0x3c7/0x640 kernel/workqueue.c:3416 kthread+0x121/0x170 kernel/kthread.c:388 ret_from_fork+0x44/0x50 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243 When fallback to TCP happens early on a client socket, snd_nxt is not yet initialized and any incoming ack will copy such value into snd_una. If the mptcp worker (dumbly) tries mptcp-level re-injection after such ack, that would unconditionally trigger a send buffer cleanup using 'bad' snd_una values. We could easily disable re-injection for fallback sockets, but such dumb behavior already helped catching a few subtle issues and a very low to zero impact in practice. Instead address the issue always initializing snd_nxt (and write_seq, for consistency) at connect time. Fixes: 8fd738049ac3 ("mptcp: fallback in case of simultaneous connect") Cc: stable@vger.kernel.org Reported-by: Christoph Paasch Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/485 Tested-by: Christoph Paasch Signed-off-by: Paolo Abeni Reviewed-by: Mat Martineau Signed-off-by: Matthieu Baerts (NGI0) Link: https://lore.kernel.org/r/20240429-upstream-net-20240429-mptcp-snd_nxt-init-connect-v1-1-59ceac0a7dcb@kernel.org Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/mptcp/protocol.c | 3 +++ 1 file changed, 3 insertions(+) --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -3703,6 +3703,9 @@ static int mptcp_connect(struct sock *sk MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_TOKENFALLBACKINIT); mptcp_subflow_early_fallback(msk, subflow); } + + WRITE_ONCE(msk->write_seq, subflow->idsn); + WRITE_ONCE(msk->snd_nxt, subflow->idsn); if (likely(!__mptcp_check_fallback(msk))) MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVE);