Re: [PATCH] vdpa/mlx5: fix param validation in mlx5_vdpa_get_config()

[Stefano Garzarella]

On Tue, Feb 09, 2021 at 07:43:02AM +0200, Eli Cohen wrote:
> On Mon, Feb 08, 2021 at 05:17:41PM +0100, Stefano Garzarella wrote:
> > It's legal to have 'offset + len' equal to
> > sizeof(struct virtio_net_config), since 'ndev->config' is a
> > 'struct virtio_net_config', so we can safely copy its content under
> > this condition.
> >
> > Fixes: 1a86b377aa21 ("vdpa/mlx5: Add VDPA driver for supported mlx5 devices")
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
>
> Acked-by: Eli Cohen <elic@xxxxxxxxxx>
>
> BTW, same error in vdpa_sim you may want to fix.

Commit 65b709586e22 ("vdpa_sim: add get_config callback in 
vdpasim_dev_attr") unintentionally solved it.

Since it's a simulator, maybe we can avoid solving it in the stable 
branches. Or does it matter?

Thanks,
Stefano

> > ---
> >  drivers/vdpa/mlx5/net/mlx5_vnet.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > index dc88559a8d49..10e9b09932eb 100644
> > --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > @@ -1820,7 +1820,7 @@ static void mlx5_vdpa_get_config(struct vdpa_device *vdev, unsigned int offset,
> >  	struct mlx5_vdpa_dev *mvdev = to_mvdev(vdev);
> >  	struct mlx5_vdpa_net *ndev = to_mlx5_vdpa_ndev(mvdev);
> >
> > -	if (offset + len < sizeof(struct virtio_net_config))
> > +	if (offset + len <= sizeof(struct virtio_net_config))
> >  		memcpy(buf, (u8 *)&ndev->config + offset, len);
> >  }
> >
> > --
> > 2.29.2