On Sat, Jun 28, 2025 at 8:48 AM Jakub Kicinski <k...@kernel.org> wrote:
>
> On Thu, 26 Jun 2025 10:14:45 +0800 Jason Wang wrote:
> > --- a/drivers/vhost/net.c
> > +++ b/drivers/vhost/net.c
> > @@ -690,13 +690,13 @@ static int vhost_net_build_xdp(struct
> > vhost_net_virtqueue *nvq,
> > if (unlikely(!buf))
> > return -ENOMEM;
> >
> > - copied = copy_from_iter(buf, sock_hlen, from);
> > - if (copied != sock_hlen) {
> > + copied = copy_from_iter(buf + pad - sock_hlen, len, from);
> > + if (copied != len) {
> > ret = -EFAULT;
> > goto err;
> > }
> >
> > - gso = buf;
> > + gso = buf + pad - sock_hlen;
> >
> > if (!sock_hlen)
> > memset(buf, 0, pad);
> > @@ -715,12 +715,8 @@ static int vhost_net_build_xdp(struct
> > vhost_net_virtqueue *nvq,
> > }
> > }
> >
> > - len -= sock_hlen;
>
> we used to adjust @len here, now we don't..
>
> > - copied = copy_from_iter(buf + pad, len, from);
> > - if (copied != len) {
> > - ret = -EFAULT;
> > - goto err;
> > - }
> > + /* pad contains sock_hlen */
> > + memcpy(buf, buf + pad - sock_hlen, sock_hlen);
> >
> > xdp_init_buff(xdp, buflen, NULL);
> > xdp_prepare_buff(xdp, buf, pad, len, true);
>
> .. yet we still use len as the packet size here.
Exactly, it should be len - sock_hlen here.
Thanks
> --
> pw-bot: cr
>
