Messages in this thread | | | Subject | Re: [PATCH bpf-next] xsk: proper socket state check in xsk_poll | From | Daniel Borkmann <> | Date | Tue, 20 Aug 2019 16:30:27 +0200 |
| |
On 8/20/19 12:04 PM, Björn Töpel wrote: > From: Björn Töpel <bjorn.topel@intel.com> > > 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 <hdanton@sina.com> > 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 <bjorn.topel@intel.com> > --- > 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
| |