linux-kernel - Re: [PATCH v2 02/17] virtio: pci-legacy: Validate queue pfn

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Date:   Fri, 13 Jul 2018 03:36:12 +0300
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Suzuki K Poulose <suzuki.poulose@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kvmarm@...ts.cs.columbia.edu, kvm@...r.kernel.org,
        cdall@...nel.org, marc.zyngier@....com, punit.agrawal@....com,
        will.deacon@....com, catalin.marinas@....com, pbonzini@...hat.com,
        rkrcmar@...hat.com, ard.biesheuvel@...aro.org,
        peter.maydell@...aro.org, kristina.martsenko@....com,
        mark.rutland@....com, Jason Wang <jasowang@...hat.com>,
        Jean-Philippe Brucker <jean-philippe.brucker@....com>
Subject: Re: [PATCH v2 02/17] virtio: pci-legacy: Validate queue pfn

On Tue, Mar 27, 2018 at 05:11:04PM +0300, Michael S. Tsirkin wrote:
> On Tue, Mar 27, 2018 at 02:15:12PM +0100, Suzuki K Poulose wrote:
> > Legacy PCI over virtio uses a 32bit PFN for the queue. If the
> > queue pfn is too large to fit in 32bits, which we could hit on
> > arm64 systems with 52bit physical addresses (even with 64K page
> > size), we simply miss out a proper link to the other side of
> > the queue.
> > 
> > Add a check to validate the PFN, rather than silently breaking
> > the devices.
> > 
> > Cc: "Michael S. Tsirkin" <mst@...hat.com>
> > Cc: Jason Wang <jasowang@...hat.com>
> > Cc: Marc Zyngier <marc.zyngier@....com>
> > Cc: Christoffer Dall <cdall@...nel.org>
> > Cc: Peter Maydel <peter.maydell@...aro.org>
> > Cc: Jean-Philippe Brucker <jean-philippe.brucker@....com>
> > Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
> > ---
> >  drivers/virtio/virtio_pci_legacy.c | 12 ++++++++++--
> >  1 file changed, 10 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/virtio/virtio_pci_legacy.c b/drivers/virtio/virtio_pci_legacy.c
> > index 2780886..4b84a75 100644
> > --- a/drivers/virtio/virtio_pci_legacy.c
> > +++ b/drivers/virtio/virtio_pci_legacy.c
> > @@ -122,6 +122,7 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
> >  	struct virtqueue *vq;
> >  	u16 num;
> >  	int err;
> > +	u64 q_pfn;
> >  
> >  	/* Select the queue we're interested in */
> >  	iowrite16(index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
> > @@ -141,9 +142,15 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
> >  	if (!vq)
> >  		return ERR_PTR(-ENOMEM);
> >  
> > +	q_pfn = virtqueue_get_desc_addr(vq) >> VIRTIO_PCI_QUEUE_ADDR_SHIFT;
> > +	if (q_pfn >> 32) {
> > +		dev_err(&vp_dev->pci_dev->dev, "virtio-pci queue PFN too large\n");
> > +		err = -ENOMEM;
> 
> ENOMEM seems wrong here. E2BIG?
> 
> > +		goto out_del_vq;
> > +	}
> > +
> >  	/* activate the queue */
> > -	iowrite32(virtqueue_get_desc_addr(vq) >> VIRTIO_PCI_QUEUE_ADDR_SHIFT,
> > -		  vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
> > +	iowrite32((u32)q_pfn, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
> 
> Is the cast really necessary here?
> 
> >  
> >  	vq->priv = (void __force *)vp_dev->ioaddr + VIRTIO_PCI_QUEUE_NOTIFY;
> >  
> > @@ -160,6 +167,7 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
> >  
> >  out_deactivate:
> >  	iowrite32(0, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
> > +out_del_vq:
> >  	vring_del_virtqueue(vq);
> >  	return ERR_PTR(err);
> >  }
> > -- 
> > 2.7.4

Ping are you going to address and repost, or should I drop this?

-- 
MST