From mboxrd@z Thu Jan 1 00:00:00 1970 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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 4FAACC3A59D for ; Tue, 20 Aug 2019 14:30:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 300D4214DA for ; Tue, 20 Aug 2019 14:30:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730135AbfHTOag (ORCPT ); Tue, 20 Aug 2019 10:30:36 -0400 Received: from www62.your-server.de ([213.133.104.62]:48460 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728770AbfHTOaf (ORCPT ); Tue, 20 Aug 2019 10:30:35 -0400 Received: from sslproxy01.your-server.de ([88.198.220.130]) by www62.your-server.de with esmtpsa (TLSv1.2:DHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89_1) (envelope-from ) id 1i059Z-0005CZ-DM; Tue, 20 Aug 2019 16:30:29 +0200 Received: from [178.197.249.40] (helo=pc-63.home) by sslproxy01.your-server.de with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1i059Y-0003x3-U5; Tue, 20 Aug 2019 16:30:29 +0200 Subject: Re: [PATCH bpf-next] xsk: proper socket state check in xsk_poll To: =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= , syzbot+c82697e3043781e08802@syzkaller.appspotmail.com, ast@kernel.org, netdev@vger.kernel.org Cc: bjorn.topel@intel.com, bpf@vger.kernel.org, davem@davemloft.net, hawk@kernel.org, jakub.kicinski@netronome.com, john.fastabend@gmail.com, jonathan.lemon@gmail.com, kafai@fb.com, linux-kernel@vger.kernel.org, magnus.karlsson@intel.com, songliubraving@fb.com, syzkaller-bugs@googlegroups.com, xdp-newbies@vger.kernel.org, yhs@fb.com, hdanton@sina.com References: <0000000000009167320590823a8c@google.com> <20190820100405.25564-1-bjorn.topel@gmail.com> From: Daniel Borkmann Message-ID: Date: Tue, 20 Aug 2019 16:30:27 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20190820100405.25564-1-bjorn.topel@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Authenticated-Sender: daniel@iogearbox.net X-Virus-Scanned: Clear (ClamAV 0.100.3/25547/Tue Aug 20 10:27:49 2019) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/20/19 12:04 PM, Björn Töpel wrote: > From: Björn Töpel > > The poll() implementation for AF_XDP sockets did not perform the > proper state checks, prior accessing the socket umem. This patch fixes > that by performing a xsk_is_bound() check. > > Suggested-by: Hillf Danton > Reported-by: syzbot+c82697e3043781e08802@syzkaller.appspotmail.com > Fixes: 77cd0d7b3f25 ("xsk: add support for need_wakeup flag in AF_XDP rings") > Signed-off-by: Björn Töpel > --- > net/xdp/xsk.c | 14 ++++++++++++-- > 1 file changed, 12 insertions(+), 2 deletions(-) > > diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c > index ee4428a892fa..08bed5e92af4 100644 > --- a/net/xdp/xsk.c > +++ b/net/xdp/xsk.c > @@ -356,13 +356,20 @@ static int xsk_generic_xmit(struct sock *sk, struct msghdr *m, > return err; > } > > +static bool xsk_is_bound(struct xdp_sock *xs) > +{ > + struct net_device *dev = READ_ONCE(xs->dev); > + > + return dev && xs->state == XSK_BOUND; > +} > + > static int xsk_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len) > { > bool need_wait = !(m->msg_flags & MSG_DONTWAIT); > struct sock *sk = sock->sk; > struct xdp_sock *xs = xdp_sk(sk); > > - if (unlikely(!xs->dev)) > + if (unlikely(!xsk_is_bound(xs))) > return -ENXIO; > if (unlikely(!(xs->dev->flags & IFF_UP))) > return -ENETDOWN; > @@ -383,6 +390,9 @@ static unsigned int xsk_poll(struct file *file, struct socket *sock, > struct net_device *dev = xs->dev; > struct xdp_umem *umem = xs->umem; > > + if (unlikely(!xsk_is_bound(xs))) > + return mask; > + > if (umem->need_wakeup) > dev->netdev_ops->ndo_xsk_wakeup(dev, xs->queue_id, > umem->need_wakeup); > @@ -417,7 +427,7 @@ static void xsk_unbind_dev(struct xdp_sock *xs) > { > struct net_device *dev = xs->dev; > > - if (!dev || xs->state != XSK_BOUND) > + if (!xsk_is_bound(xs)) > return; I think I'm a bit confused by your READ_ONCE() usage. ;-/ I can see why you're using it in xsk_is_bound() above, but then at the same time all the other callbacks like xsk_poll() or xsk_unbind_dev() above have a struct net_device *dev = xs->dev right before the test. Could you elaborate? Thanks, Daniel