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 30461134C7 for ; Mon, 26 Jun 2023 18:17:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5470AC433C8; Mon, 26 Jun 2023 18:17:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1687803462; bh=rETuzVcX12314GtalFMQien40k2C25yqlrDrg5bOBcM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=w2RSLu/VYjwQd6rJQEvWz421HD5m3VGCYihjDo4wvRjlMyFGaiFA6/9gpykmaHeYY BLF+azllyrvSMpYSTpG4Uh3WL49TOre7b7hmvLQ/JnUHyAocqvBKezj6HBkY61+4YJ rZP5avuiOTyz0hZeWKD6O0Bpy2PIIWKnTgr9ifV8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Paolo Abeni , Christoph Paasch , Matthieu Baerts , Jakub Kicinski Subject: [PATCH 6.3 070/199] mptcp: handle correctly disconnect() failures Date: Mon, 26 Jun 2023 20:09:36 +0200 Message-ID: <20230626180808.600098813@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230626180805.643662628@linuxfoundation.org> References: <20230626180805.643662628@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Paolo Abeni commit c2b2ae3925b65070adb27d5a31a31c376f26dec7 upstream. Currently the mptcp code has assumes that disconnect() can fail only at mptcp_sendmsg_fastopen() time - to avoid a deadlock scenario - and don't even bother returning an error code. Soon mptcp_disconnect() will handle more error conditions: let's track them explicitly. As a bonus, explicitly annotate TCP-level disconnect as not failing: the mptcp code never blocks for event on the subflows. Fixes: 7d803344fdc3 ("mptcp: fix deadlock in fastopen error path") Cc: stable@vger.kernel.org Signed-off-by: Paolo Abeni Tested-by: Christoph Paasch Reviewed-by: Matthieu Baerts Signed-off-by: Matthieu Baerts Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/mptcp/protocol.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -1696,7 +1696,13 @@ static int mptcp_sendmsg_fastopen(struct if (ret && ret != -EINPROGRESS && ret != -ERESTARTSYS && ret != -EINTR) *copied_syn = 0; } else if (ret && ret != -EINPROGRESS) { - mptcp_disconnect(sk, 0); + /* The disconnect() op called by tcp_sendmsg_fastopen()/ + * __inet_stream_connect() can fail, due to looking check, + * see mptcp_disconnect(). + * Attempt it again outside the problematic scope. + */ + if (!mptcp_disconnect(sk, 0)) + sk->sk_socket->state = SS_UNCONNECTED; } return ret; @@ -2360,7 +2366,10 @@ static void __mptcp_close_ssk(struct soc need_push = (flags & MPTCP_CF_PUSH) && __mptcp_retransmit_pending_data(sk); if (!dispose_it) { - tcp_disconnect(ssk, 0); + /* The MPTCP code never wait on the subflow sockets, TCP-level + * disconnect should never fail + */ + WARN_ON_ONCE(tcp_disconnect(ssk, 0)); msk->subflow->state = SS_UNCONNECTED; mptcp_subflow_ctx_reset(subflow); release_sock(ssk); @@ -2787,7 +2796,7 @@ void mptcp_subflow_shutdown(struct sock break; fallthrough; case TCP_SYN_SENT: - tcp_disconnect(ssk, O_NONBLOCK); + WARN_ON_ONCE(tcp_disconnect(ssk, O_NONBLOCK)); break; default: if (__mptcp_check_fallback(mptcp_sk(sk))) { @@ -3047,11 +3056,10 @@ static int mptcp_disconnect(struct sock /* We are on the fastopen error path. We can't call straight into the * subflows cleanup code due to lock nesting (we are already under - * msk->firstsocket lock). Do nothing and leave the cleanup to the - * caller. + * msk->firstsocket lock). */ if (msk->fastopening) - return 0; + return -EBUSY; mptcp_listen_inuse_dec(sk); inet_sk_state_store(sk, TCP_CLOSE);