vhost: do not try to access device IOTLB when not initialized

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@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 549771a0cd8b..5727b186b3ca 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);