virtio-net: correctly drop truncated packets

When packet is truncated during receiving, we drop the packets but
neither discard the descriptor nor add and signal used
descriptor. This will lead several issues:

- sg mappings are leaked
- rx will be stalled if a lots of packets were truncated

In order to be consistent with vhost, fix by discarding the descriptor
in this case.

Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

(cherry picked from commit 0cf33fb6b49a19de32859e2cdc6021334f448fb3)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

1 files changed, 1 insertions, 7 deletions

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 887a836229..4aa93fb931 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -1086,13 +1086,7 @@ static ssize_t virtio_net_receive(NetClientState *nc, const uint8_t *buf, size_t
          * must have consumed the complete packet.
          * Otherwise, drop it. */
         if (!n->mergeable_rx_bufs && offset < size) {
-#if 0
-            error_report("virtio-net truncated non-mergeable packet: "
-                         "i %zd mergeable %d offset %zd, size %zd, "
-                         "guest hdr len %zd, host hdr len %zd",
-                         i, n->mergeable_rx_bufs,
-                         offset, size, n->guest_hdr_len, n->host_hdr_len);
-#endif
+            virtqueue_discard(q->rx_vq, &elem, total);
             return size;
         }