From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 A38A82C82 for ; Thu, 16 Dec 2021 14:34:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1639665254; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=/T5bDPGlZhTkj3fm7orBGfwMxMMUCH7yToTR22nKMfk=; b=UCA54zjG1wgtqD14YQ8XDlSM9ahjG2yp8JBRqm/VoyjxrPnTiYYiZ2xWHebCM9q1uozUet Ya8qHyVF5paO1ckqLdEcopvr5rtdfY1cBwNX91i+5V9SegWQkTYgSieJ2tVMPWuhXNh9Ss gaKTE9kv/DuPKhDkpsyqvSU6F3pndQ0= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-450-LDObtUoRPaOKTUCXyO4FXw-1; Thu, 16 Dec 2021 09:34:11 -0500 X-MC-Unique: LDObtUoRPaOKTUCXyO4FXw-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 0551039393 for ; Thu, 16 Dec 2021 14:34:11 +0000 (UTC) Received: from gerbillo.redhat.com (unknown [10.39.193.243]) by smtp.corp.redhat.com (Postfix) with ESMTP id 66ECD60C7F for ; Thu, 16 Dec 2021 14:34:10 +0000 (UTC) From: Paolo Abeni To: mptcp@lists.linux.dev Subject: [PATCH mptcp-next] Squash-to: "mptcp: cleanup MPJ subflow list handling" Date: Thu, 16 Dec 2021 15:33:37 +0100 Message-Id: <70e15da075bab481ac07ed1ce8c2adc9740403c6.1639665203.git.pabeni@redhat.com> Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pabeni@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="US-ASCII" The self-tests in a loop triggered a UaF similar to: https://github.com/multipath-tcp/mptcp_net-next/issues/250 The critical scenario is actually almost fixed by: "mptcp: cleanup MPJ subflow list handling" with a notable exception: if an MPJ handshake races with mptcp_close(), the subflow enter the join_list and __mptcp_finish_join() is processed at the msk socket lock release in mptcp_close(), the subflow will preserver a danfling reference to the msk sk_socket. Address the issue fragting the subflow only on successful __mptcp_finish_join() Note that issues/250 triggers even before "mptcp: cleanup MPJ subflow list handling", as before such commit the join list was not spliced by mptcp_close(). We could consider a net-only patch to address that. Signed-off-by: Paolo Abeni --- net/mptcp/protocol.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index e81fd46a43c4..e89d7741aa7f 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -810,9 +810,17 @@ void mptcp_data_ready(struct sock *sk, struct sock *ssk) static bool __mptcp_finish_join(struct mptcp_sock *msk, struct sock *ssk) { - if (((struct sock *)msk)->sk_state != TCP_ESTABLISHED) + struct sock *sk = (struct sock *)msk; + + if (sk->sk_state != TCP_ESTABLISHED) return false; + /* attach to msk socket only after we are sure we will deal with it + * at close time + */ + if (sk->sk_socket && !ssk->sk_socket) + mptcp_sock_graft(ssk, sk->sk_socket); + mptcp_propagate_sndbuf((struct sock *)msk, ssk); mptcp_sockopt_sync_locked(msk, ssk); WRITE_ONCE(msk->allow_infinite_fallback, false); @@ -3234,7 +3242,6 @@ bool mptcp_finish_join(struct sock *ssk) struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); struct mptcp_sock *msk = mptcp_sk(subflow->conn); struct sock *parent = (void *)msk; - struct socket *parent_sock; bool ret = true; pr_debug("msk=%p, subflow=%p", msk, subflow); @@ -3278,13 +3285,6 @@ bool mptcp_finish_join(struct sock *ssk) return false; } - /* attach to msk socket only after we are sure he will deal with us - * at close time - */ - parent_sock = READ_ONCE(parent->sk_socket); - if (parent_sock && !ssk->sk_socket) - mptcp_sock_graft(ssk, parent_sock); - subflow->map_seq = READ_ONCE(msk->ack_seq); out: -- 2.33.1