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 9D5A9266571; Mon, 14 Jul 2025 16:42:08 +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=1752511328; cv=none; b=gaZnl1aHKzXWQTtK0CKEgBLM5NF3RMFxW+RdUd/hPEJ0x6/KA5qC+uqAbzyF2K0e57725sCQGn+lysANZeBR84LMl47pKXIXCwOVf9LEi+Otu33DCVH5CIkPC/H25IbNmw1Pz1FEKs8C9yG9DpvHYU10H8lCdohp0iB0TpHGROg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752511328; c=relaxed/simple; bh=1N7+GeRvg3UlhrQNvi0MzXHzXlGklkvNQD2n2ZPlph0=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=Ik0bUBHDNR4KJR4vVLYmL7wNO71K2czqRjbqhHCQ0D7WG0aaro/w8YToQQzCl7wMWXLuXL7R9+Bo8dlz7ZkMGppVN6Hs8Ej+fNKwGvEKxXZufxb4DjlGC8ErGJqZBZoHWNge4BTas4/5bbgf28QHNY5LGjZGfBmEeEJnAFXHuIs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=pWe8IheH; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="pWe8IheH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 21763C4CEED; Mon, 14 Jul 2025 16:42:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752511328; bh=1N7+GeRvg3UlhrQNvi0MzXHzXlGklkvNQD2n2ZPlph0=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=pWe8IheHYI0DOKkc6IvgLlhe0xFiK3bUyYa+43WIUQ89a/NR0SQkrtc3VOjv6IWAD ibCIUX30Odfewdkm9HJJiXll0L+DqSFmyvFGt03L0qa1HOZVxoMy2keQD7BS0NNUeO 6uqo5bXsoW9pmt91VhogxjiCfbmfxmiOTFzPLLDLCvAqFM6Zm5jOYpGM60yEeT8eM/ fqoUcZb+zvShhRMO6clllWcD3/ycL1+1LQkendAecvDj1CAV9kbe1LqoTsfH9lSP+d HobSkNHGjYtiRUPC8bDptauPUCm2tG+RwIj87azWMn/GopRA2wZ4FwzzEdN3jZ9QH2 XQrHcTQfEj4MA== From: "Matthieu Baerts (NGI0)" Date: Mon, 14 Jul 2025 18:41:46 +0200 Subject: [PATCH net 3/3] mptcp: reset fallback status gracefully at disconnect() time Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20250714-net-mptcp-fallback-races-v1-3-391aff963322@kernel.org> References: <20250714-net-mptcp-fallback-races-v1-0-391aff963322@kernel.org> In-Reply-To: <20250714-net-mptcp-fallback-races-v1-0-391aff963322@kernel.org> To: mptcp@lists.linux.dev, Mat Martineau , Geliang Tang , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "Matthieu Baerts (NGI0)" , stable@vger.kernel.org X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=1498; i=matttbe@kernel.org; h=from:subject:message-id; bh=gfDHvhkpq8awEepc0HtZrNS8nkt/GbmvMC5YwhaAY2I=; b=owGbwMvMwCVWo/Th0Gd3rumMp9WSGDJKjUNNt1vzCmyOOG/gm3qv/POWFp+o3uyDydIKLRxC7 TZlk1w6SlkYxLgYZMUUWaTbIvNnPq/iLfHys4CZw8oEMoSBi1MAJjJ1L8P/RNtv0/58nJMsWvSO S8noSHyQ4gy1ilLdiJVfXV8fbrbkYGTYL1rs1a3lVaGnV6kpfcU+xsalbflMS0/HnJlapuF9tTw A X-Developer-Key: i=matttbe@kernel.org; a=openpgp; fpr=E8CB85F76877057A6E27F77AF6B7824F4269A073 From: Paolo Abeni mptcp_disconnect() clears the fallback bit unconditionally, without touching the associated flags. The bit clear is safe, as no fallback operation can race with that -- all subflow are already in TCP_CLOSE status thanks to the previous FASTCLOSE -- but we need to consistently reset all the fallback related status. Also acquire the relevant lock, to avoid fouling static analyzers. Fixes: b29fcfb54cd7 ("mptcp: full disconnect implementation") Cc: stable@vger.kernel.org Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) --- net/mptcp/protocol.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index bf92cee9b5cee39e2b0831b6f7e06ce013fb6913..6a817a13b1549c3397e8fa2e315448ce2770e195 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -3142,7 +3142,16 @@ static int mptcp_disconnect(struct sock *sk, int flags) * subflow */ mptcp_destroy_common(msk, MPTCP_CF_FASTCLOSE); + + /* The first subflow is already in TCP_CLOSE status, the following + * can't overlap with a fallback anymore + */ + spin_lock_bh(&msk->fallback_lock); + msk->allow_subflows = true; + msk->allow_infinite_fallback = true; WRITE_ONCE(msk->flags, 0); + spin_unlock_bh(&msk->fallback_lock); + msk->cb_flags = 0; msk->recovery = false; WRITE_ONCE(msk->can_ack, false); -- 2.48.1