net/virtio: fix uninitialized RSS key

[ upstream commit 0f7438e ]

This patch fixes an issue that uninitialized old_rss_key
is used for restoring the rss_key.

Coverity issue: 373866
Fixes: 0c9d662 ("net/virtio: support RSS")

Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
Reviewed-by: Chenbo Xia <chenbo.xia@intel.com>

drivers/net/virtio/virtio_ethdev.c

@@ -2028,7 +2028,8 @@ virtio_dev_rss_hash_update(struct rte_eth_dev *dev,
 
 	return 0;
 restore_key:
-	memcpy(hw->rss_key, old_rss_key, VIRTIO_NET_RSS_KEY_SIZE);
+	if (rss_conf->rss_key && rss_conf->rss_key_len)
+		memcpy(hw->rss_key, old_rss_key, VIRTIO_NET_RSS_KEY_SIZE);
 restore_types:
 	hw->rss_hash_types = old_hash_types;