Re: [PATCH vhost v3 3/4] virtio_pci: add check for common cfg size

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On Tue, Oct 10, 2023 at 3:58 PM Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote:
>
> On Tue, 10 Oct 2023 14:41:39 +0800, Jason Wang <jasowang@xxxxxxxxxx> wrote:
> > On Tue, Oct 10, 2023 at 11:11 AM Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote:
> > >
> > > Some buggy devices, the common cfg size may not match the features.
> > >
> > > This patch checks the common cfg size for the
> > > features(VIRTIO_F_NOTIF_CONFIG_DATA, VIRTIO_F_RING_RESET). When the
> > > common cfg size does not match the corresponding feature, we fail the
> > > probe and print error message.
> > >
> > > Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
> > > ---
> > >  drivers/virtio/virtio_pci_modern.c     | 36 ++++++++++++++++++++++++++
> > >  drivers/virtio/virtio_pci_modern_dev.c |  2 +-
> > >  include/linux/virtio_pci_modern.h      |  1 +
> > >  3 files changed, 38 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
> > > index d6bb68ba84e5..6a8f5ff05636 100644
> > > --- a/drivers/virtio/virtio_pci_modern.c
> > > +++ b/drivers/virtio/virtio_pci_modern.c
> > > @@ -39,6 +39,39 @@ static void vp_transport_features(struct virtio_device *vdev, u64 features)
> > >                 __virtio_set_bit(vdev, VIRTIO_F_RING_RESET);
> > >  }
> > >
> > > +static int __vp_check_common_size_one_feature(struct virtio_device *vdev, u32 fbit,
> > > +                                           u32 offset, const char *fname)
> > > +{
> > > +       struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> > > +
> > > +       if (!__virtio_test_bit(vdev, fbit))
> > > +               return 0;
> > > +
> > > +       if (likely(vp_dev->mdev.common_len >= offset))
> > > +               return 0;
> > > +
> > > +       dev_err(&vdev->dev,
> > > +               "virtio: common cfg size(%ld) does not match the feature %s\n",
> > > +               vp_dev->mdev.common_len, fname);
> > > +
> > > +       return -EINVAL;
> > > +}
> > > +
> > > +#define vp_check_common_size_one_feature(vdev, fbit, field) \
> > > +       __vp_check_common_size_one_feature(vdev, fbit, \
> > > +               offsetofend(struct virtio_pci_modern_common_cfg, field), #fbit)
> > > +
> > > +static int vp_check_common_size(struct virtio_device *vdev)
> > > +{
> > > +       if (vp_check_common_size_one_feature(vdev, VIRTIO_F_NOTIF_CONFIG_DATA, queue_notify_data))
> > > +               return -EINVAL;
> > > +
> > > +       if (vp_check_common_size_one_feature(vdev, VIRTIO_F_RING_RESET, queue_reset))
> > > +               return -EINVAL;
> >
> > Do we need to at least check the offset of the queue_device as well here?
>
>
> Not need.
>
>
> /*
>  * vp_modern_map_capability - map a part of virtio pci capability
>  * @mdev: the modern virtio-pci device
>  * @off: offset of the capability
>  * @minlen: minimal length of the capability
>  * @align: align requirement
>  * @start: start from the capability
>  * @size: map size
>  * @len: the length that is actually mapped
>  * @pa: physical address of the capability
>  *
>  * Returns the io address of for the part of the capability
>  */
> static void __iomem *
> vp_modern_map_capability(struct virtio_pci_modern_device *mdev, int off,
>                          size_t minlen, u32 align, u32 start, u32 size,
>                          size_t *len, resource_size_t *pa)
>
>
>
> caller:
>         mdev->common = vp_modern_map_capability(mdev, common,
>                                       sizeof(struct virtio_pci_common_cfg), 4,
>                                       0, sizeof(struct virtio_pci_modern_common_cfg),
>                                       &mdev->common_len, NULL);
>
>
> We pass the sizeof(struct virtio_pci_common_cfg) as the minlen.
>
> So we do not need to check the common cfg size is smaller then
> sizeof(struct virtio_pci_common_cfg).

Great.

Acked-by: Jason Wang <jasowang@xxxxxxxxxx>

Thanks

>
> Thanks.
>
> >
> > Thanks
> >
> > > +
> > > +       return 0;
> > > +}
> > > +
> > >  /* virtio config->finalize_features() implementation */
> > >  static int vp_finalize_features(struct virtio_device *vdev)
> > >  {
> > > @@ -57,6 +90,9 @@ static int vp_finalize_features(struct virtio_device *vdev)
> > >                 return -EINVAL;
> > >         }
> > >
> > > +       if (vp_check_common_size(vdev))
> > > +               return -EINVAL;
> > > +
> > >         vp_modern_set_features(&vp_dev->mdev, vdev->features);
> > >
> > >         return 0;
> > > diff --git a/drivers/virtio/virtio_pci_modern_dev.c b/drivers/virtio/virtio_pci_modern_dev.c
> > > index 9cb601e16688..33f319da1558 100644
> > > --- a/drivers/virtio/virtio_pci_modern_dev.c
> > > +++ b/drivers/virtio/virtio_pci_modern_dev.c
> > > @@ -292,7 +292,7 @@ int vp_modern_probe(struct virtio_pci_modern_device *mdev)
> > >         mdev->common = vp_modern_map_capability(mdev, common,
> > >                                       sizeof(struct virtio_pci_common_cfg), 4,
> > >                                       0, sizeof(struct virtio_pci_modern_common_cfg),
> > > -                                     NULL, NULL);
> > > +                                     &mdev->common_len, NULL);
> > >         if (!mdev->common)
> > >                 goto err_map_common;
> > >         mdev->isr = vp_modern_map_capability(mdev, isr, sizeof(u8), 1,
> > > diff --git a/include/linux/virtio_pci_modern.h b/include/linux/virtio_pci_modern.h
> > > index 067ac1d789bc..edf62bae0474 100644
> > > --- a/include/linux/virtio_pci_modern.h
> > > +++ b/include/linux/virtio_pci_modern.h
> > > @@ -28,6 +28,7 @@ struct virtio_pci_modern_device {
> > >         /* So we can sanity-check accesses. */
> > >         size_t notify_len;
> > >         size_t device_len;
> > > +       size_t common_len;
> > >
> > >         /* Capability for when we need to map notifications per-vq. */
> > >         int notify_map_cap;
> > > --
> > > 2.32.0.3.g01195cf9f
> > >
> >
> > _______________________________________________
> > Virtualization mailing list
> > Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
> > https://lists.linuxfoundation.org/mailman/listinfo/virtualization
>

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