Re: [Qemu-devel] [PULL 08/22] virtio-pci: Proxy for virtio-pmem

[Peter Maydell <peter.maydell@linaro.org>]

On Tue, 2 Jul 2019 at 16:07, Michael S. Tsirkin <mst@redhat.com> wrote:
>
> From: Pankaj Gupta <pagupta@redhat.com>
>
> We need a proxy device for virtio-pmem, and this device has to be the
> actual memory device so we can cleanly hotplug it.
>
> Forward memory device class functions either to the actual device or use
> properties of the virtio-pmem device to implement these in the proxy.
>
> virtio-pmem will only be compiled for selected, supported architectures
> (that can deal with virtio/pci devices being memory devices). An
> architecture that is prepared for that can simply enable
> CONFIG_VIRTIO_PMEM to make it work.
>
> As not all architectures support memory devices (and CONFIG_VIRTIO_PMEM
> will be enabled per supported architecture), we have to move the PCI proxy
> to a separate file.
>
> Signed-off-by: Pankaj Gupta <pagupta@redhat.com>
> [ split up patches, memory-device changes, move pci proxy]
> Signed-off-by: David Hildenbrand <david@redhat.com>
> Message-Id: <20190619094907.10131-5-pagupta@redhat.com>
> Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---

Hi; Coverity spotted a bug here (CID 1403010):

> +static uint64_t virtio_pmem_pci_get_plugged_size(const MemoryDeviceState *md,
> +                                                 Error **errp)
> +{
> +    VirtIOPMEMPCI *pci_pmem = VIRTIO_PMEM_PCI(md);
> +    VirtIOPMEM *pmem = VIRTIO_PMEM(&pci_pmem->vdev);
> +    VirtIOPMEMClass *vpc = VIRTIO_PMEM_GET_CLASS(pmem);
> +    MemoryRegion *mr = vpc->get_memory_region(pmem, errp);
> +
> +    /* the plugged size corresponds to the region size */
> +    return mr ? 0 : memory_region_size(mr);

This looks like maybe the arguments to ?: have been put
the wrong way round? If mr is non-NULL we'll return 0
and if it is NULL then we'll crash because memory_region_size()
dereferences mr...

> +}

thanks
-- PMM