Re: [Qemu-devel] [PATCH V5 for 3.1 5/5] virtio-net-test: add large tx buffer test

[Thomas Huth]

On 2018-12-04 04:53, Jason Wang wrote:
> This test tries to build a packet whose size is greater than INT_MAX
> which tries to trigger integer overflow in qemu_net_queue_append_iov()
> which may result OOB.
> 
> Signed-off-by: Jason Wang <address@hidden>
> ---
>  tests/virtio-net-test.c | 46 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 46 insertions(+)
> 
> diff --git a/tests/virtio-net-test.c b/tests/virtio-net-test.c
> index bdd6af9999..e9783e6707 100644
> --- a/tests/virtio-net-test.c
> +++ b/tests/virtio-net-test.c
> @@ -245,6 +245,48 @@ static void pci_basic(gconstpointer data)
>      g_free(dev);
>      qtest_shutdown(qs);
>  }
> +
> +static void large_tx(gconstpointer data)
> +{
> +    QVirtioPCIDevice *dev;
> +    QOSState *qs;
> +    QVirtQueuePCI *tx, *rx;
> +    QVirtQueue *vq;
> +    uint64_t req_addr;
> +    uint32_t free_head;
> +    size_t alloc_size = (size_t)data / 64;
> +    int i;
> +
> +    qs = pci_test_start("-netdev hubport,id=hp0,hubid=0 "
> +                        "-device virtio-net-pci,netdev=hp0");
> +    dev = virtio_net_pci_init(qs->pcibus, PCI_SLOT);
> +
> +    rx = (QVirtQueuePCI *)qvirtqueue_setup(&dev->vdev, qs->alloc, 0);
> +    tx = (QVirtQueuePCI *)qvirtqueue_setup(&dev->vdev, qs->alloc, 1);
> +
> +    driver_init(&dev->vdev);
> +    vq = &tx->vq;
> +
> +    /* Bypass the limitation by pointing several descriptors to a single
> +     * smaller area */
> +    req_addr = guest_alloc(qs->alloc, alloc_size);
> +    free_head = qvirtqueue_add(vq, req_addr, alloc_size, false, true);
> +
> +    for (i = 0; i < 64; i++) {
> +        qvirtqueue_add(vq, req_addr, alloc_size, false, i != 63);
> +    }
> +    qvirtqueue_kick(&dev->vdev, vq, free_head);
> +
> +    qvirtio_wait_used_elem(&dev->vdev, vq, free_head, NULL,
> +                           QVIRTIO_NET_TIMEOUT_US);
> +
> +    qvirtqueue_cleanup(dev->vdev.bus, &tx->vq, qs->alloc);
> +    qvirtqueue_cleanup(dev->vdev.bus, &rx->vq, qs->alloc);
> +    qvirtio_pci_device_disable(dev);
> +    g_free(dev->pdev);
> +    g_free(dev);
> +    qtest_shutdown(qs);
> +}
>  #endif
>  
>  static void hotplug(void)
> @@ -270,6 +312,10 @@ int main(int argc, char **argv)
>      qtest_add_data_func("/virtio/net/pci/basic", send_recv_test, pci_basic);
>      qtest_add_data_func("/virtio/net/pci/rx_stop_cont",
>                          stop_cont_test, pci_basic);
> +    qtest_add_data_func("/virtio/net/pci/large_tx_uint_max",
> +                        (gconstpointer)UINT_MAX, large_tx);
> +    qtest_add_data_func("/virtio/net/pci/large_tx_net_bufsize",
> +                        (gconstpointer)NET_BUFSIZE, large_tx);
>  #endif
>      qtest_add_func("/virtio/net/pci/hotplug", hotplug);
>  
> 

Looks reasonable to me. In case you respin again, it might maybe be a
good idea to set the RAM size of the guest ("-m 256" or something
similar), but AFAIK all off the guests where we run this test have
enough memory by default, so this should not be an issue.

Reviewed-by: Thomas Huth <address@hidden>