virtio-net: Avoid indirection_table_mask overflow

We computes indirections_len by adding 1 to indirection_table_mask, but
it may overflow indirection_table_mask is UINT16_MAX. Check if
indirection_table_mask is small enough before adding 1.

Fixes: 590790297c0d ("virtio-net: implement RSS configuration command")
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

hw/net/virtio-net.c

@@ -1406,17 +1406,17 @@ static uint16_t virtio_net_handle_rss(VirtIONet *n,
     n->rss_data.hash_types = virtio_ldl_p(vdev, &cfg.hash_types);
     n->rss_data.indirections_len =
         virtio_lduw_p(vdev, &cfg.indirection_table_mask);
-    n->rss_data.indirections_len++;
     if (!do_rss) {
-        n->rss_data.indirections_len = 1;
+        n->rss_data.indirections_len = 0;
     }
-    if (!is_power_of_2(n->rss_data.indirections_len)) {
-        err_msg = "Invalid size of indirection table";
+    if (n->rss_data.indirections_len >= VIRTIO_NET_RSS_MAX_TABLE_LEN) {
+        err_msg = "Too large indirection table";
         err_value = n->rss_data.indirections_len;
         goto error;
     }
-    if (n->rss_data.indirections_len > VIRTIO_NET_RSS_MAX_TABLE_LEN) {
-        err_msg = "Too large indirection table";
+    n->rss_data.indirections_len++;
+    if (!is_power_of_2(n->rss_data.indirections_len)) {
+        err_msg = "Invalid size of indirection table";
         err_value = n->rss_data.indirections_len;
         goto error;
     }