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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 2B1E2C352AA for ; Tue, 1 Oct 2019 22:19:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 09D1A21924 for ; Tue, 1 Oct 2019 22:19:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728813AbfJAWT5 (ORCPT ); Tue, 1 Oct 2019 18:19:57 -0400 Received: from www62.your-server.de ([213.133.104.62]:38786 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728254AbfJAWT5 (ORCPT ); Tue, 1 Oct 2019 18:19:57 -0400 Received: from 57.248.197.178.dynamic.dsl-lte-bonding.zhbmb00p-msn.res.cust.swisscom.ch ([178.197.248.57] helo=localhost) by www62.your-server.de with esmtpsa (TLSv1.2:DHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89_1) (envelope-from ) id 1iFQUm-0005we-UW; Wed, 02 Oct 2019 00:19:49 +0200 Date: Wed, 2 Oct 2019 00:19:48 +0200 From: Daniel Borkmann To: Magnus Karlsson Cc: bjorn.topel@intel.com, ast@kernel.org, netdev@vger.kernel.org, jonathan.lemon@gmail.com, bpf@vger.kernel.org Subject: Re: [PATCH bpf] xsk: fix crash in poll when device does not support ndo_xsk_wakeup Message-ID: <20191001221948.GA10044@pc-63.home> References: <1569850212-4035-1-git-send-email-magnus.karlsson@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1569850212-4035-1-git-send-email-magnus.karlsson@intel.com> User-Agent: Mutt/1.12.1 (2019-06-15) X-Authenticated-Sender: daniel@iogearbox.net X-Virus-Scanned: Clear (ClamAV 0.101.4/25589/Tue Oct 1 10:30:33 2019) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, Sep 30, 2019 at 03:30:12PM +0200, Magnus Karlsson wrote: > Fixes a crash in poll() when an AF_XDP socket is opened in copy mode > with the XDP_USE_NEED_WAKEUP flag set and the bound device does not > have ndo_xsk_wakeup defined. Avoid trying to call the non-existing ndo > and instead call the internal xsk sendmsg functionality to send > packets in the same way (from the application's point of view) as > calling sendmsg() in any mode or poll() in zero-copy mode would have > done. The application should behave in the same way independent on if > zero-copy mode or copy-mode is used. > > Fixes: 77cd0d7b3f25 ("xsk: add support for need_wakeup flag in AF_XDP rings") > Reported-by: syzbot+a5765ed8cdb1cca4d249@syzkaller.appspotmail.com > Signed-off-by: Magnus Karlsson Overall looks good, two very small nits: > --- > net/xdp/xsk.c | 33 +++++++++++++++++++++++---------- > 1 file changed, 23 insertions(+), 10 deletions(-) > > diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c > index c2f1af3..a478d8ec 100644 > --- a/net/xdp/xsk.c > +++ b/net/xdp/xsk.c > @@ -327,8 +327,7 @@ static void xsk_destruct_skb(struct sk_buff *skb) > sock_wfree(skb); > } > > -static int xsk_generic_xmit(struct sock *sk, struct msghdr *m, > - size_t total_len) > +static int xsk_generic_xmit(struct sock *sk) > { > u32 max_batch = TX_BATCH_SIZE; > struct xdp_sock *xs = xdp_sk(sk); > @@ -394,22 +393,31 @@ static int xsk_generic_xmit(struct sock *sk, struct msghdr *m, > return err; > } > > -static int xsk_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len) > +static int __xsk_sendmsg(struct socket *sock) > { > - bool need_wait = !(m->msg_flags & MSG_DONTWAIT); > struct sock *sk = sock->sk; > struct xdp_sock *xs = xdp_sk(sk); Can't we just only pass xs as an argument to __xsk_sendmsg()? From below xsk_sendmsg() we eventually fetch xs anyway same as for the xsk_poll(), yet in __xsk_sendmsg() we pass sock (which is otherwise unused) and then we need to refetch sk and xs once again. > - if (unlikely(!xsk_is_bound(xs))) > - return -ENXIO; > if (unlikely(!(xs->dev->flags & IFF_UP))) > return -ENETDOWN; > if (unlikely(!xs->tx)) > return -ENOBUFS; > + > + return xs->zc ? xsk_zc_xmit(sk) : xsk_generic_xmit(sk); > +} > + > +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(!xsk_is_bound(xs))) > + return -ENXIO; > if (need_wait) Not directly related but since you touch this code, need_wait should be marked unlikely() as well. > return -EOPNOTSUPP; > > - return (xs->zc) ? xsk_zc_xmit(sk) : xsk_generic_xmit(sk, m, total_len); > + return __xsk_sendmsg(sock); > } > > static unsigned int xsk_poll(struct file *file, struct socket *sock, > @@ -426,9 +434,14 @@ static unsigned int xsk_poll(struct file *file, struct socket *sock, > dev = xs->dev; > umem = xs->umem; > > - if (umem->need_wakeup) > - dev->netdev_ops->ndo_xsk_wakeup(dev, xs->queue_id, > - umem->need_wakeup); > + if (umem->need_wakeup) { > + if (dev->netdev_ops->ndo_xsk_wakeup) > + dev->netdev_ops->ndo_xsk_wakeup(dev, xs->queue_id, > + umem->need_wakeup); > + else > + /* Poll needs to drive Tx also in copy mode */ > + __xsk_sendmsg(sock); > + } > > if (xs->rx && !xskq_empty_desc(xs->rx)) > mask |= POLLIN | POLLRDNORM; > -- > 2.7.4 >