Re: [PATCH net 2/2] vhost: do not try to access device IOTLB when not initialized

[Michael S. Tsirkin]

On Tue, Jan 23, 2018 at 05:27:26PM +0800, Jason Wang wrote:
> The code will try to access dev->iotlb when processing
> VHOST_IOTLB_INVALIDATE even if it was not initialized which may lead
> to NULL pointer dereference. Fixes this by check dev->iotlb before.
> 
> Fixes: 6b1e6cc7855b0 ("vhost: new device IOTLB API")
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>

Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>

> ---
>  drivers/vhost/vhost.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index 549771a..5727b18 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -1015,6 +1015,10 @@ static int vhost_process_iotlb_msg(struct vhost_dev *dev,
>  		vhost_iotlb_notify_vq(dev, msg);
>  		break;
>  	case VHOST_IOTLB_INVALIDATE:
> +		if (!dev->iotlb) {
> +			ret = -EFAULT;
> +			break;
> +		}
>  		vhost_vq_meta_reset(dev);
>  		vhost_del_umem_range(dev->iotlb, msg->iova,
>  				     msg->iova + msg->size - 1);
> -- 
> 2.7.4