Check vring size and fail probe if a transmit/receive vring size is
smaller than MAX_SKB_FRAGS + 2.
At the moment, any vring size is accepted. This is problematic because
it may result in attempting to transmit a packet with more fragments
than there are descriptors in the ring.
Furthermore, it leads to an immediate bug:
The condition: (sq->vq->num_free >= 2 + MAX_SKB_FRAGS) in
virtnet_poll_cleantx and virtnet_poll_tx always evaluates to false,
so netif_tx_wake_queue is not called, leading to TX timeouts.
Signed-off-by: Alvaro Karsz <alvaro.karsz@xxxxxxxxxxxxx>
---
drivers/net/virtio_net.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 2396c28c012..59676252c5c 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -3745,6 +3745,26 @@ static int init_vqs(struct virtnet_info *vi)
return ret;
}
+static int virtnet_validate_vqs(struct virtnet_info *vi)
+{
+ u32 i, min_size = roundup_pow_of_two(MAX_SKB_FRAGS + 2);
+
+ /* Transmit/Receive vring size must be at least MAX_SKB_FRAGS + 2
+ * (fragments + linear part + virtio header)
+ */
+ for (i = 0; i < vi->max_queue_pairs; i++) {
+ if (virtqueue_get_vring_size(vi->sq[i].vq) < min_size ||
+ virtqueue_get_vring_size(vi->rq[i].vq) < min_size) {
+ dev_warn(&vi->vdev->dev,
+ "Transmit/Receive virtqueue vring size must be at least %u\n",
+ min_size);
+ return -EINVAL;
+ }
+ }
+
+ return 0;
+}
+
#ifdef CONFIG_SYSFS
static ssize_t mergeable_rx_buffer_size_show(struct netdev_rx_queue *queue,
char *buf)
@@ -4056,6 +4076,10 @@ static int virtnet_probe(struct virtio_device *vdev)
if (err)
goto free;
+ err = virtnet_validate_vqs(vi);
+ if (err)
+ goto free_vqs;
+
#ifdef CONFIG_SYSFS
if (vi->mergeable_rx_bufs)
dev->sysfs_rx_queue_group = &virtio_net_mrg_rx_group;
--
2.34.1
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