Re: [PATCH] vhost-vdpa: Set s.num in GET_VRING_GROUP

[Eugenio Perez Martin]

On Sat, Sep 27, 2025 at 2:25 PM Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
>
> The group is supposed to be copied to the user, but it wasn't assigned
> until after the copy_to_user().  Move the "s.num = group;" earlier.
>
> Fixes: ffc3634b6696 ("vduse: add vq group support")
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> ---
> This goes through the kvm tree I think.
>
>  drivers/vhost/vdpa.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index 6305382eacbb..25ab4d06e559 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -667,9 +667,9 @@ static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd,
>                 group = ops->get_vq_group(vdpa, idx);
>                 if (group >= vdpa->ngroups || group > U32_MAX || group < 0)
>                         return -EIO;
> -               else if (copy_to_user(argp, &s, sizeof(s)))
> -                       return -EFAULT;
>                 s.num = group;
> +               if (copy_to_user(argp, &s, sizeof(s)))
> +                       return -EFAULT;
>                 return 0;
>         }
>         case VHOST_VDPA_GET_VRING_DESC_GROUP:


Thank you very much for the report Dan! that should be fixed in v5.