From: Jan Beulich <jbeulich@suse.com>
To: Juergen Gross <jgross@suse.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Stefano Stabellini <sstabellini@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
xen-devel@lists.xenproject.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 5/8] xen/netfront: read response from backend only once
Date: Mon, 17 May 2021 16:20:21 +0200 [thread overview]
Message-ID: <c9f90370-fc02-3f05-0670-35f795c59d95@suse.com> (raw)
In-Reply-To: <20210513100302.22027-6-jgross@suse.com>
On 13.05.2021 12:02, Juergen Gross wrote:
> In order to avoid problems in case the backend is modifying a response
> on the ring page while the frontend has already seen it, just read the
> response into a local buffer in one go and then operate on that buffer
> only.
>
> Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
with one remark:
> @@ -830,24 +830,22 @@ static int xennet_get_extras(struct netfront_queue *queue,
> break;
> }
>
> - extra = (struct xen_netif_extra_info *)
> - RING_GET_RESPONSE(&queue->rx, ++cons);
> + RING_COPY_RESPONSE(&queue->rx, ++cons, &extra);
>
> - if (unlikely(!extra->type ||
> - extra->type >= XEN_NETIF_EXTRA_TYPE_MAX)) {
> + if (unlikely(!extra.type ||
> + extra.type >= XEN_NETIF_EXTRA_TYPE_MAX)) {
> if (net_ratelimit())
> dev_warn(dev, "Invalid extra type: %d\n",
> - extra->type);
> + extra.type);
> err = -EINVAL;
> } else {
> - memcpy(&extras[extra->type - 1], extra,
> - sizeof(*extra));
> + memcpy(&extras[extra.type - 1], &extra, sizeof(extra));
Maybe take the opportunity and switch to (type safe) structure
assignment?
Jan
next prev parent reply other threads:[~2021-05-17 14:22 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-13 10:02 [PATCH 0/8] xen: harden frontends against malicious backends Juergen Gross
2021-05-13 10:02 ` [PATCH 5/8] xen/netfront: read response from backend only once Juergen Gross
2021-05-17 14:20 ` Jan Beulich [this message]
2021-05-17 14:24 ` Juergen Gross
2021-05-13 10:03 ` [PATCH 6/8] xen/netfront: don't read data from request on the ring page Juergen Gross
2021-05-17 15:08 ` Jan Beulich
2021-05-13 10:03 ` [PATCH 7/8] xen/netfront: don't trust the backend response data blindly Juergen Gross
2021-05-17 15:31 ` Jan Beulich
2021-05-21 10:43 ` [PATCH 0/8] xen: harden frontends against malicious backends Marek Marczykowski-Górecki
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