Re: Resource leak in unshare

From: Eric Dumazet
Date: Mon Nov 02 2015 - 20:08:54 EST


From: Eric Dumazet <edumazet@xxxxxxxxxx>

sit0 device allocates its percpu storage twice :
- One time in ipip6_tunnel_init()
- One time in ipip6_fb_tunnel_init()

Thus we leak 48 bytes per possible cpu per network namespace dismantle.

ipip6_fb_tunnel_init() can be much simpler and does not
return an error, and should be called after register_netdev()

Note that ipip6_tunnel_clone_6rd() also needs to be called
after register_netdev() (calling ipip6_tunnel_init())

Fixes: ebe084aafb7e ("sit: Use ipip6_tunnel_init as the ndo_init function.")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
---

net/ipv6/sit.c | 26 ++++----------------------
1 file changed, 4 insertions(+), 22 deletions(-)

diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index 94428fd85b2f..dcccae86190f 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -1394,34 +1394,20 @@ static int ipip6_tunnel_init(struct net_device *dev)
return 0;
}

-static int __net_init ipip6_fb_tunnel_init(struct net_device *dev)
+static void __net_init ipip6_fb_tunnel_init(struct net_device *dev)
{
struct ip_tunnel *tunnel = netdev_priv(dev);
struct iphdr *iph = &tunnel->parms.iph;
struct net *net = dev_net(dev);
struct sit_net *sitn = net_generic(net, sit_net_id);

- tunnel->dev = dev;
- tunnel->net = dev_net(dev);
-
iph->version = 4;
iph->protocol = IPPROTO_IPV6;
iph->ihl = 5;
iph->ttl = 64;

- dev->tstats = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats);
- if (!dev->tstats)
- return -ENOMEM;
-
- tunnel->dst_cache = alloc_percpu(struct ip_tunnel_dst);
- if (!tunnel->dst_cache) {
- free_percpu(dev->tstats);
- return -ENOMEM;
- }
-
dev_hold(dev);
rcu_assign_pointer(sitn->tunnels_wc[0], tunnel);
- return 0;
}

static int ipip6_validate(struct nlattr *tb[], struct nlattr *data[])
@@ -1831,23 +1817,19 @@ static int __net_init sit_init_net(struct net *net)
*/
sitn->fb_tunnel_dev->features |= NETIF_F_NETNS_LOCAL;

- err = ipip6_fb_tunnel_init(sitn->fb_tunnel_dev);
- if (err)
- goto err_dev_free;
-
- ipip6_tunnel_clone_6rd(sitn->fb_tunnel_dev, sitn);
err = register_netdev(sitn->fb_tunnel_dev);
if (err)
goto err_reg_dev;

+ ipip6_tunnel_clone_6rd(sitn->fb_tunnel_dev, sitn);
+ ipip6_fb_tunnel_init(sitn->fb_tunnel_dev);
+
t = netdev_priv(sitn->fb_tunnel_dev);

strcpy(t->parms.name, sitn->fb_tunnel_dev->name);
return 0;

err_reg_dev:
- dev_put(sitn->fb_tunnel_dev);
-err_dev_free:
ipip6_dev_free(sitn->fb_tunnel_dev);
err_alloc_dev:
return err;


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