Re: net/ipv6: double free in ipip6_dev_free

From: Cong Wang
Date: Wed Feb 08 2017 - 12:12:09 EST


On Wed, Feb 8, 2017 at 5:56 AM, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote:
> First dev->tstats was freed here:
>
> 1376 static int ipip6_tunnel_init(struct net_device *dev)
> 1377 {
> 1378 struct ip_tunnel *tunnel = netdev_priv(dev);
> 1379 int err;
> 1380
> 1381 tunnel->dev = dev;
> 1382 tunnel->net = dev_net(dev);
> 1383 strcpy(tunnel->parms.name, dev->name);
> 1384
> 1385 ipip6_tunnel_bind_dev(dev);
> 1386 dev->tstats = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats);
> 1387 if (!dev->tstats)
> 1388 return -ENOMEM;
> 1389
> 1390 err = dst_cache_init(&tunnel->dst_cache, GFP_KERNEL);
> 1391 if (err) {
> 1392 free_percpu(dev->tstats);
> 1393 return err;
> 1394 }
> 1395
> 1396 return 0;
> 1397 }
>
> And then again here:
>
> 1342 static void ipip6_dev_free(struct net_device *dev)
> 1343 {
> 1344 struct ip_tunnel *tunnel = netdev_priv(dev);
> 1345
> 1346 dst_cache_destroy(&tunnel->dst_cache);
> 1347 free_percpu(dev->tstats);
> 1348 free_netdev(dev);
> 1349 }

Probably we need to NULL dev->tstats in the ndo_init(),
and ipip6 tunnel seems not the only one missing it.