From patchwork Tue Aug 4 16:31:06 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Abeni X-Patchwork-Id: 262728 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7927BC433DF for ; Tue, 4 Aug 2020 16:32:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 599FA22B42 for ; Tue, 4 Aug 2020 16:32:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="QbaAsRjQ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729703AbgHDQcc (ORCPT ); Tue, 4 Aug 2020 12:32:32 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:49071 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726027AbgHDQcc (ORCPT ); Tue, 4 Aug 2020 12:32:32 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1596558751; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=j9V+gTlssMRevtKd/lBIjqmGOHHv08UaijZNfxpImIc=; b=QbaAsRjQRrFpNZAucxyXu8Hk1BeJZEM1V3FfBnmkwUi40fSUaP6r5oqOGunuk2HquQ6yxC Whv4QY8DtoPvp8aWpSaem7GkNTiq1+rHRxc/Y+DheZs1Gb24mXActSeAIXmRy1oTu6tJHA lWG/0r2WW/VAC9m8VAkMax1KD8Pkgng= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-438-EBmKu7AiPXulOTPglffOXA-1; Tue, 04 Aug 2020 12:32:29 -0400 X-MC-Unique: EBmKu7AiPXulOTPglffOXA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id ED74C1800D42; Tue, 4 Aug 2020 16:32:27 +0000 (UTC) Received: from linux.fritz.box.com (ovpn-114-132.ams2.redhat.com [10.36.114.132]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4C4F072E48; Tue, 4 Aug 2020 16:32:26 +0000 (UTC) From: Paolo Abeni To: netdev@vger.kernel.org Cc: "David S. Miller" , Jakub Kicinski , mptcp@lists.01.org, Nicolas Rybowski Subject: [PATCH net] mptcp: be careful on subflow creation Date: Tue, 4 Aug 2020 18:31:06 +0200 Message-Id: <61e82de664dffde9ff445ed6f776d6809b198693.1596558566.git.pabeni@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Nicolas reported the following oops: [ 1521.392541] BUG: kernel NULL pointer dereference, address: 00000000000000c0 [ 1521.394189] #PF: supervisor read access in kernel mode [ 1521.395376] #PF: error_code(0x0000) - not-present page [ 1521.396607] PGD 0 P4D 0 [ 1521.397156] Oops: 0000 [#1] SMP PTI [ 1521.398020] CPU: 0 PID: 22986 Comm: kworker/0:2 Not tainted 5.8.0-rc4+ #109 [ 1521.399618] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 [ 1521.401728] Workqueue: events mptcp_worker [ 1521.402651] RIP: 0010:mptcp_subflow_create_socket+0xf1/0x1c0 [ 1521.403954] Code: 24 08 89 44 24 04 48 8b 7a 18 e8 2a 48 d4 ff 8b 44 24 04 85 c0 75 7a 48 8b 8b 78 02 00 00 48 8b 54 24 08 48 8d bb 80 00 00 00 <48> 8b 89 c0 00 00 00 48 89 8a c0 00 00 00 48 8b 8b 78 02 00 00 8b [ 1521.408201] RSP: 0000:ffffabc4002d3c60 EFLAGS: 00010246 [ 1521.409433] RAX: 0000000000000000 RBX: ffffa0b9ad8c9a00 RCX: 0000000000000000 [ 1521.411096] RDX: ffffa0b9ae78a300 RSI: 00000000fffffe01 RDI: ffffa0b9ad8c9a80 [ 1521.412734] RBP: ffffa0b9adff2e80 R08: ffffa0b9af02d640 R09: ffffa0b9ad923a00 [ 1521.414333] R10: ffffabc4007139f8 R11: fefefefefefefeff R12: ffffabc4002d3cb0 [ 1521.415918] R13: ffffa0b9ad91fa58 R14: ffffa0b9ad8c9f9c R15: 0000000000000000 [ 1521.417592] FS: 0000000000000000(0000) GS:ffffa0b9af000000(0000) knlGS:0000000000000000 [ 1521.419490] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1521.420839] CR2: 00000000000000c0 CR3: 000000002951e006 CR4: 0000000000160ef0 [ 1521.422511] Call Trace: [ 1521.423103] __mptcp_subflow_connect+0x94/0x1f0 [ 1521.425376] mptcp_pm_create_subflow_or_signal_addr+0x200/0x2a0 [ 1521.426736] mptcp_worker+0x31b/0x390 [ 1521.431324] process_one_work+0x1fc/0x3f0 [ 1521.432268] worker_thread+0x2d/0x3b0 [ 1521.434197] kthread+0x117/0x130 [ 1521.435783] ret_from_fork+0x22/0x30 on some unconventional configuration. The MPTCP protocol is trying to create a subflow for an unaccepted server socket. That is allowed by the RFC, even if subflow creation will likely fail. Unaccepted sockets have still a NULL sk_socket field, avoid the issue by failing earlier. Reported-and-tested-by: Nicolas Rybowski Fixes: 7d14b0d2b9b3 ("mptcp: set correct vfs info for subflows") Signed-off-by: Paolo Abeni --- net/mptcp/subflow.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 3838a0b3a21f..3c31a8160f19 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -1032,6 +1032,12 @@ int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock) struct socket *sf; int err; + /* un-accepted server sockets can reach here - on bad configuration + * bail early to avoid greater trouble later + */ + if (unlikely(!sk->sk_socket)) + return -EINVAL; + err = sock_create_kern(net, sk->sk_family, SOCK_STREAM, IPPROTO_TCP, &sf); if (err)