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> > > - else > > > + vfio_pci_dma_buf_move(vdev, true); > > > + } else { > > > down_write(&vdev->memory_lock); > > > + } > > > > shouldn't we notify move before zapping the bars? otherwise there is > > still a small window in between where the exporter already has the > > mapping cleared while the importer still keeps it... >=20 > zapping the VMA and moving/revoking the DMABUF are independent > operations that can happen in any order. They effect different kinds > of users. The VMA zap prevents CPU access from userspace, the DMABUF > move prevents DMA access from devices. The comment was triggered by the description about UAF in the=20 commit msg. >=20 > The order has to be like the above because vfio_pci_dma_buf_move() > must be called under the memory lock and > vfio_pci_zap_and_down_write_memory_lock() gets the memory lock.. make sense. > > > + down_write(&vdev->memory_lock); > > > + list_for_each_entry_safe(priv, tmp, &vdev->dmabufs, dmabufs_elm) > > > { > > > + if (!get_file_active(&priv->dmabuf->file)) > > > + continue; > > > + > > > + dma_resv_lock(priv->dmabuf->resv, NULL); > > > + list_del_init(&priv->dmabufs_elm); > > > + priv->vdev =3D NULL; > > > + priv->revoked =3D true; > > > + dma_buf_move_notify(priv->dmabuf); > > > + dma_resv_unlock(priv->dmabuf->resv); > > > + vfio_device_put_registration(&vdev->vdev); > > > + fput(priv->dmabuf->file); > > > > dma_buf_put(priv->dmabuf), consistent with other places. >=20 > Someone else said this, I don't agree, the above got the get via >=20 > get_file_active() instead of a dma_buf version.. >=20 > So we should pair with get_file_active() vs fput(). >=20 > Christian rejected the idea of adding a dmabuf wrapper for > get_file_active(), oh well. Okay then vfio_pci_dma_buf_move() should be changed. It uses get_file_active() to pair dma_buf_put().