net/virtio: fix dangling pointer on failure

[ upstream commit 7dee8c7 ]

When eth_virtio_dev_init() is cleaning up, it does not correctly set
the mac_addrs variable to NULL, which will lead to a double free.

Found during unit-test fixes.

Fixes: 43d1876 ("net/virtio: fix memory leak on failure")

Reported-by: Michael Santana <msantana@redhat.com>
Signed-off-by: Aaron Conole <aconole@redhat.com>
Reviewed-by: Tiwei Bie <tiwei.bie@intel.com>

drivers/net/virtio/virtio_ethdev.c

@@ -1708,6 +1708,7 @@ eth_virtio_dev_init(struct rte_eth_dev *eth_dev)
 
 out:
 	rte_free(eth_dev->data->mac_addrs);
+	eth_dev->data->mac_addrs = NULL;
 	return ret;
 }