Re: [PATCH v3] vduse: Fix off by one in vduse_dev_mmap()

[Cindy Lu]

On Thu, Feb 29, 2024 at 3:19 AM Stefan Hajnoczi <stefanha@xxxxxxxxx> wrote:
>
> On Wed, 28 Feb 2024 at 13:24, Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
> >
> > The dev->vqs[] array has "dev->vq_num" elements.  It's allocated in
> > vduse_dev_init_vqs().  Thus, this > comparison needs to be >= to avoid
> > reading one element beyond the end of the array.
> >
> > Add an array_index_nospec() as well to prevent speculation issues.
> >
> > Fixes: 316ecd1346b0 ("vduse: Add file operation for mmap")
> > Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> > ---
> > v2: add array_index_nospec()
> > v3: I accidentally corrupted v2.  Try again.
> >
Thanks for fix this
> >  drivers/vdpa/vdpa_user/vduse_dev.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
>
> Reviewed-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx>
Reviewed-by:  Cindy Lu <lulu@xxxxxxxxxx>
> > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> > index b7a1fb88c506..eb914084c650 100644
> > --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> > @@ -1532,9 +1532,10 @@ static int vduse_dev_mmap(struct file *file, struct vm_area_struct *vma)
> >         if ((vma->vm_flags & VM_SHARED) == 0)
> >                 return -EINVAL;
> >
> > -       if (index > dev->vq_num)
> > +       if (index >= dev->vq_num)
> >                 return -EINVAL;
> >
> > +       index = array_index_nospec(index, dev->vq_num);
> >         vq = dev->vqs[index];
> >         vaddr = vq->vdpa_reconnect_vaddr;
> >         if (vaddr == 0)
> > --
> > 2.43.0
> >
> >
>