linux-kernel - Re: [PATCH net] virtio-net: alloc big buffers also when guest can receive UFO

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20140213051559.GB31352@redhat.com>
Date:	Thu, 13 Feb 2014 07:15:59 +0200
From:	"Michael S. Tsirkin" <mst@...hat.com>
To:	Jason Wang <jasowang@...hat.com>
Cc:	rusty@...tcorp.com.au, virtio-dev@...ts.oasis-open.org,
	virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, Sridhar Samudrala <sri@...ibm.com>
Subject: Re: [PATCH net] virtio-net: alloc big buffers also when guest can
 receive UFO

On Thu, Feb 13, 2014 at 11:02:13AM +0800, Jason Wang wrote:
> On 02/12/2014 07:59 PM, Michael S. Tsirkin wrote:
> > On Wed, Feb 12, 2014 at 01:43:28PM +0800, Jason Wang wrote:
> >> > We should alloc big buffers also when guest can receive UFO
> >> > pakcets. Otherwise the big packets will be truncated when mergeable rx
> >> > buffer is disabled.
> > Not truncated, they will be dropped.
> >
> 
> Why dropped? We enable the ufo on tap0 if VIRTIO_NET_F_GUEST_UFO is
> negotiated. So skb was queued on the receive queue. But since the
> receive buffer is small, it will be truncated during tun_put_user().

Hypervisor shouldn't truncate packets silently - if it does
it's a hypervisor bug. Passing malformed packets to guest is
a bad idea.

-- 
MST
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/