@@ -2765,18 +2765,14 @@ static int32_t virtio_net_flush_tx(VirtIONetQueue *q)
out_sg = elem->out_sg;
if (out_num < 1) {
virtio_error(vdev, "virtio-net header not in first element");
- virtqueue_detach_element(q->tx_vq, elem, 0);
- g_free(elem);
- return -EINVAL;
+ goto detach;
}
if (n->has_vnet_hdr) {
if (iov_to_buf(out_sg, out_num, 0, &vhdr, n->guest_hdr_len) <
n->guest_hdr_len) {
virtio_error(vdev, "virtio-net header incorrect");
- virtqueue_detach_element(q->tx_vq, elem, 0);
- g_free(elem);
- return -EINVAL;
+ goto detach;
}
if (n->needs_vnet_hdr_swap) {
virtio_net_hdr_swap(vdev, (void *) &vhdr);
@@ -2807,6 +2803,11 @@ static int32_t virtio_net_flush_tx(VirtIONetQueue *q)
n->guest_hdr_len, -1);
out_num = sg_num;
out_sg = sg;
+
+ if (out_num < 1) {
+ virtio_error(vdev, "virtio-net nothing to send");
+ goto detach;
+ }
}
ret = qemu_sendv_packet_async(qemu_get_subqueue(n->nic, queue_index),
@@ -2827,6 +2828,11 @@ drop:
}
}
return num_packets;
+
+detach:
+ virtqueue_detach_element(q->tx_vq, elem, 0);
+ g_free(elem);
+ return -EINVAL;
}
static void virtio_net_tx_timer(void *opaque);
Reproducer from https://gitlab.com/qemu-project/qemu/-/issues/1451 creates small packet (1 segment, len=10 == n->guest_hdr_len), destroys queue. "if (n->host_hdr_len != n->guest_hdr_len)" is triggered. There is nothing after guest header, if body creates zero length/zero segment packet. qemu_sendv_packet_async() tries to send it. Packet is discarded inside net_slirp_receive() which returns number of sent bytes which is 0. 0 is propagated upwards and is interpreted as "zero bytes has been sent" which is terrible because queue is being destroyed, nobody is waiting for TX to complete, TX complete hook is _not_ called and assert(async_tx.elem) is eventually triggered. The fix is to discard such phantom packets in virtio_net_flush_tx(). Signed-off-by: Alexey Dobriyan <adobriyan@yandex-team.ru> --- hw/net/virtio-net.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-)