On Wed, Apr 11, 2018 at 12:25:24AM +0200, Greg Kroah-Hartman wrote:
> 4.14-stable review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: Jason Wang <jasowang@xxxxxxxxxx>
>
>
> [ Upstream commit d65026c6c62e7d9616c8ceb5a53b68bcdc050525 ]
>
> Vq log_base is the userspace address of bitmap which has nothing to do
> with IOTLB. So it needs to be validated unconditionally otherwise we
> may try use 0 as log_base which may lead to pin pages that will lead
> unexpected result (e.g trigger BUG_ON() in set_bit_to_user()).
>
> Fixes: 6b1e6cc7855b0 ("vhost: new device IOTLB API")
> Reported-by: syzbot+6304bf97ef436580fede@xxxxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> ---
> drivers/vhost/vhost.c | 14 ++++++--------
> 1 file changed, 6 insertions(+), 8 deletions(-)
>
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -1252,14 +1252,12 @@ static int vq_log_access_ok(struct vhost
> /* Caller should have vq mutex and device mutex */
> int vhost_vq_access_ok(struct vhost_virtqueue *vq)
> {
> - if (vq->iotlb) {
> - /* When device IOTLB was used, the access validation
> - * will be validated during prefetching.
> - */
> - return 1;
> - }
> - return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used) &&
> - vq_log_access_ok(vq, vq->log_base);
> + int ret = vq_log_access_ok(vq, vq->log_base);
> +
> + if (ret || vq->iotlb)
That's a bug, davem just queued a patch to fix this upstream.
> + return ret;
> +
> + return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used);
> }
> EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
>
>