On Thu, Aug 11, 2022 at 01:11:11PM +0000, Eli Cohen wrote:
> > From: Michael S. Tsirkin <mst@xxxxxxxxxx>
> > Sent: Thursday, August 11, 2022 4:09 PM
> > To: Eli Cohen <elic@xxxxxxxxxx>
> > Cc: Dan Carpenter <dan.carpenter@xxxxxxxxxx>; Jason Wang <jasowang@xxxxxxxxxx>; Eugenio Perez Martin
> > <eperezma@xxxxxxxxxx>; virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
> > Subject: Re: [bug report] vdpa/mlx5: Support different address spaces for control and data
> >
> > On Thu, Aug 11, 2022 at 12:40:09PM +0000, Eli Cohen wrote:
> > > > From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> > > > Sent: Thursday, August 11, 2022 1:40 PM
> > > > To: Eli Cohen <elic@xxxxxxxxxx>
> > > > Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
> > > > Subject: [bug report] vdpa/mlx5: Support different address spaces for control and data
> > > >
> > > > Hello Eli Cohen,
> > > >
> > > > The patch d5358cd0e369: "vdpa/mlx5: Support different address spaces
> > > > for control and data" from Jul 14, 2022, leads to the following
> > > > Smatch static checker warning:
> > > >
> > > > drivers/vdpa/mlx5/net/mlx5_vnet.c:2676 mlx5_vdpa_set_map()
> > > > error: uninitialized symbol 'err'.
> > > >
> > > > drivers/vdpa/mlx5/net/mlx5_vnet.c
> > > > 2657 static int mlx5_vdpa_set_map(struct vdpa_device *vdev, unsigned int asid,
> > > > 2658 struct vhost_iotlb *iotlb)
> > > > 2659 {
> > > > 2660 struct mlx5_vdpa_dev *mvdev = to_mvdev(vdev);
> > > > 2661 struct mlx5_vdpa_net *ndev = to_mlx5_vdpa_ndev(mvdev);
> > > > 2662 int err;
> > > > 2663
> > > > 2664 down_write(&ndev->reslock);
> > > > 2665 if (mvdev->group2asid[MLX5_VDPA_DATAVQ_GROUP] == asid) {
> > > > 2666 err = set_map_data(mvdev, iotlb);
> > > > 2667 if (err)
> > > > 2668 goto out;
> > > > 2669 }
> > > > 2670
> > > > 2671 if (mvdev->group2asid[MLX5_VDPA_CVQ_GROUP] == asid)
> > > > 2672 err = set_map_control(mvdev, iotlb);
> > > >
> > > > err not initialized on else path. My guess is that one or both of these
> > > > conditions has to be true and this is a false positive but I don't know
> > > > the code well enough to be sure.
> > >
> > > Thanks for reporting this.
> > > I think it would be better to return an error if the provided asid is not recognized.
> > >
> > > Therefore I am thinking about adding something like this:
> > >
> > > if (asid != mvdev->group2asid[MLX5_VDPA_DATAVQ_GROUP] &&
> > > asid != mvdev->group2asid[MLX5_VDPA_CVQ_GROUP]) {
> > > err = -EINVAL;
> > > goto out;
> > > }
> >
> > I would probably chain the conditions:
> >
> > if (mvdev->group2asid[MLX5_VDPA_DATAVQ_GROUP] == asid) {
> > } else if (mvdev->group2asid[MLX5_VDPA_CVQ_GROUP] == asid) {
> > } else {
> > err = -EINVAL;
> > goto out;
> > }
> >
> >
> > or alternatively initialize err with -EINVAL and be done with it.
> >
> This makes more sense.
> Will send a patch in an hour.
Just making sure, the only result without this patch is that
and iotlb might be created without a mapping.
But nothing terrible bad will happen things just won't work
but this userspace is already buggy.
Right?
> >
> > > >
> > > > 2673
> > > > 2674 out:
> > > > 2675 up_write(&ndev->reslock);
> > > > --> 2676 return err;
> > > > 2677 }
> > > >
> > > > regards,
> > > > dan carpenter
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