virtio-net: Ensure queue index fits with RSS

Ensure the queue index points to a valid queue when software RSS
enabled. The new calculation matches with the behavior of Linux's TAP
device with the RSS eBPF program.

Fixes: 4474e37a5b3a ("virtio-net: implement RX RSS processing")
Reported-by: Zhibin Hu <huzhibin5@huawei.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
(cherry picked from commit f1595ceb9aad36a6c1da95bcb77ab9509b38822d)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Fixes: CVE-2024-6505

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 3644bfd91bcb4b55523cacf8a91c8c4da84f7c14..f48588638dc393f0488b80ddb7bc2cc6247affa1 100644 (file)
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -1949,7 +1949,8 @@ static ssize_t virtio_net_receive_rcu(NetClientState *nc, const uint8_t *buf,
     if (!no_rss && n->rss_data.enabled && n->rss_data.enabled_software_rss) {
         int index = virtio_net_process_rss(nc, buf, size);
         if (index >= 0) {
-            NetClientState *nc2 = qemu_get_subqueue(n->nic, index);
+            NetClientState *nc2 =
+                qemu_get_subqueue(n->nic, index % n->curr_queue_pairs);
             return virtio_net_receive_rcu(nc2, buf, size, true);
         }
     }