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

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

[Dan Carpenter]

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@linaro.org>
---
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:
-- 
2.51.0

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

[Michael S. Tsirkin]

On Sat, Sep 27, 2025 at 03:25:34PM +0300, Dan Carpenter 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@linaro.org>
> ---
> This goes through the kvm tree I think.


Thanks for the patch!

IIUC this was in my tree for next, but more testing
and review found issues (like this one) so I dropped it for now.

>  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:
> -- 
> 2.51.0

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

[Eugenio Perez Martin]

On Sat, Sep 27, 2025 at 2:32 PM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Sat, Sep 27, 2025 at 03:25:34PM +0300, Dan Carpenter 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@linaro.org>
> > ---
> > This goes through the kvm tree I think.
>
>
> Thanks for the patch!
>
> IIUC this was in my tree for next, but more testing
> and review found issues (like this one) so I dropped it for now.
>

Yes, that's fixed in v5.

> >  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:
> > --
> > 2.51.0
>

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@linaro.org> 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@linaro.org>
> ---
> 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.