On Wed, Dec 8, 2021 at 6:34 PM Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
>
> In this function "c->off" is a u32 and "size" is a long. On 64bit systems
> if "c->off" is greater than "size" then "size - c->off" is a negative and
> we always return -E2BIG. But on 32bit systems the subtraction is type
> promoted to a high positive u32 value and basically any "c->len" is
> accepted.
>
> Fixes: 4c8cf31885f6 ("vhost: introduce vDPA-based backend")
> Reported-by: Xie Yongji <xieyongji@xxxxxxxxxxxxx>
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
> ---
> v4: split into a separate patch
>
> drivers/vhost/vdpa.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index 29cced1cd277..e3c4f059b21a 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -197,7 +197,7 @@ static int vhost_vdpa_config_validate(struct vhost_vdpa *v,
> struct vdpa_device *vdpa = v->vdpa;
> long size = vdpa->config->get_config_size(vdpa);
>
> - if (c->len == 0)
> + if (c->len == 0 || c->off > size)
> return -EINVAL;
>
> if (c->len > size - c->off)
> --
> 2.20.1
>
