From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50309) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ya2ls-00063Y-1Y for qemu-devel@nongnu.org; Mon, 23 Mar 2015 09:52:01 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Ya2lm-0007kI-Vi for qemu-devel@nongnu.org; Mon, 23 Mar 2015 09:51:59 -0400 Date: Mon, 23 Mar 2015 14:51:51 +0100 From: "Michael S. Tsirkin" Message-ID: <20150323145127-mutt-send-email-mst@redhat.com> References: <1426831670-11080-1-git-send-email-jasowang@redhat.com> <20150323132028.GG9268@stefanha-thinkpad.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150323132028.GG9268@stefanha-thinkpad.redhat.com> Subject: Re: [Qemu-devel] [PATCH for 2.3 V2] virtio-net: validate backend queue numbers against bus limitation List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi Cc: Jason Wang , qemu-devel@nongnu.org, qemu-stable On Mon, Mar 23, 2015 at 01:20:28PM +0000, Stefan Hajnoczi wrote: > On Fri, Mar 20, 2015 at 02:07:50PM +0800, Jason Wang wrote: > > We don't validate the backend queue numbers against bus limitation, > > this will easily crash qemu if it exceeds the limitation which will > > hit the abort() in virtio_del_queue(). An example is trying to > > starting a virtio-net device with 256 queues. E.g: > > > > ./qemu-system-x86_64 -netdev tap,id=hn0,queues=256 -device > > virtio-net-pci,netdev=hn0 > > > > Fixing this by doing the validation and fail early. > > > > Cc: Michael S. Tsirkin > > Cc: qemu-stable > > Signed-off-by: Jason Wang > > --- > > Changes from V1: > > Tweak the commit log. > > --- > > hw/net/virtio-net.c | 7 +++++++ > > 1 file changed, 7 insertions(+) > > > > diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c > > index 27adcc5..59f76bc 100644 > > --- a/hw/net/virtio-net.c > > +++ b/hw/net/virtio-net.c > > @@ -1588,6 +1588,13 @@ static void virtio_net_device_realize(DeviceState *dev, Error **errp) > > virtio_init(vdev, "virtio-net", VIRTIO_ID_NET, n->config_size); > > > > n->max_queues = MAX(n->nic_conf.peers.queues, 1); > > + if (n->max_queues * 2 + 1 > VIRTIO_PCI_QUEUE_MAX) { > > + error_setg(errp, "Invalid number of queues (= %" PRIu32 "), " > > + "must be a postive integer less than %d.", > > + n->max_queues, (VIRTIO_PCI_QUEUE_MAX - 1) / 2); > > + virtio_cleanup(vdev); > > + return; > > + } > > If VIRTIO_PCI_QUEUE_MAX is really PCI-only then this is a layering > violation. Virtio devices should not assume a particular transport > (PCI, CCW, etc). > > Either the constant should be renamed if it truly applies to all > transports, or there should be a virtio_get_max_queues() function that > lets the transport pick a value. > > That said, virtio-scsi.c already checks VIRTIO_PCI_QUEUE_MAX so maybe > this patch is fine and a cleanup should be written later: > > Reviewed-by: Stefan Hajnoczi Yes, we need to rename this constant, no problem here.