Re: [Qemu-devel] [PATCH for 3.1 4/4] virtio-net-test: add large tx buffer test

[Jason Wang]

On 2018/11/29 下午2:21, Thomas Huth wrote:

On 2018-11-29 04:12, 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 <jasow...@redhat.com>
---
  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 33d26ab079..09c220c2fa 100644
--- a/tests/virtio-net-test.c
+++ b/tests/virtio-net-test.c
@@ -245,6 +245,51 @@ 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;
+    const char *cmd = "-netdev hubport,id=hp0,hubid=0 "
+                      "-device virtio-net-pci,netdev=hp0 ";
+    uint64_t req_addr;
+    uint32_t free_head;
+    size_t alloc_size = UINT_MAX / 64;
+    int i;
+
+    qs = pci_test_start(cmd);
+    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);
+    for (i = 0; i < 64; i ++) {
+        if (i == 0)
+            free_head = qvirtqueue_add(vq, req_addr, alloc_size, false, true);
+        else
+            qvirtqueue_add(vq, req_addr, alloc_size, false, true);

QEMU coding style requires always curly braces. Maybe move the initial
case before the for-loop and then start the for loop with i=1 instead?

Ok, fix and post V2.

Thanks

+    }
+    qvirtqueue_add(vq, req_addr, alloc_size, false, false);
+    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 +315,7 @@ 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", NULL, large_tx);
  #endif
      qtest_add_func("/virtio/net/pci/hotplug", hotplug);

  Thomas