diff options
author | Willem de Bruijn <willemb@google.com> | 2013-11-13 21:27:38 -0500 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-12-08 07:29:12 -0800 |
commit | 7c9c354a180ab36acfa8ca04c206042ce3d22fb4 (patch) | |
tree | 6d9d1a5c14b9ffc0f3fce58105a76b79ff12a83a /net | |
parent | a9ac5b0bfce3f9777aa5e1512e5e605f61c81b3f (diff) |
sit: fix use after free of fb_tunnel_dev
[ Upstream commit 9434266f2c645d4fcf62a03a8e36ad8075e37943 ]
Bug: The fallback device is created in sit_init_net and assumed to be
freed in sit_exit_net. First, it is dereferenced in that function, in
sit_destroy_tunnels:
struct net *net = dev_net(sitn->fb_tunnel_dev);
Prior to this, rtnl_unlink_register has removed all devices that match
rtnl_link_ops == sit_link_ops.
Commit 205983c43700 added the line
+ sitn->fb_tunnel_dev->rtnl_link_ops = &sit_link_ops;
which cases the fallback device to match here and be freed before it
is last dereferenced.
Fix: This commit adds an explicit .delllink callback to sit_link_ops
that skips deallocation at rtnl_unlink_register for the fallback
device. This mechanism is comparable to the one in ip_tunnel.
It also modifies sit_destroy_tunnels and its only caller sit_exit_net
to avoid the offending dereference in the first place. That double
lookup is more complicated than required.
Test: The bug is only triggered when CONFIG_NET_NS is enabled. It
causes a GPF only when CONFIG_DEBUG_SLAB is enabled. Verified that
this bug exists at the mentioned commit, at davem-net HEAD and at
3.11.y HEAD. Verified that it went away after applying this patch.
Fixes: 205983c43700 ("sit: allow to use rtnl ops on fb tunnel")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net')
-rw-r--r-- | net/ipv6/sit.c | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c index 19269453a8ea..b43388452bf8 100644 --- a/net/ipv6/sit.c +++ b/net/ipv6/sit.c @@ -1594,6 +1594,15 @@ static const struct nla_policy ipip6_policy[IFLA_IPTUN_MAX + 1] = { #endif }; +static void ipip6_dellink(struct net_device *dev, struct list_head *head) +{ + struct net *net = dev_net(dev); + struct sit_net *sitn = net_generic(net, sit_net_id); + + if (dev != sitn->fb_tunnel_dev) + unregister_netdevice_queue(dev, head); +} + static struct rtnl_link_ops sit_link_ops __read_mostly = { .kind = "sit", .maxtype = IFLA_IPTUN_MAX, @@ -1605,6 +1614,7 @@ static struct rtnl_link_ops sit_link_ops __read_mostly = { .changelink = ipip6_changelink, .get_size = ipip6_get_size, .fill_info = ipip6_fill_info, + .dellink = ipip6_dellink, }; static struct xfrm_tunnel sit_handler __read_mostly = { @@ -1619,9 +1629,10 @@ static struct xfrm_tunnel ipip_handler __read_mostly = { .priority = 2, }; -static void __net_exit sit_destroy_tunnels(struct sit_net *sitn, struct list_head *head) +static void __net_exit sit_destroy_tunnels(struct net *net, + struct list_head *head) { - struct net *net = dev_net(sitn->fb_tunnel_dev); + struct sit_net *sitn = net_generic(net, sit_net_id); struct net_device *dev, *aux; int prio; @@ -1696,11 +1707,10 @@ err_alloc_dev: static void __net_exit sit_exit_net(struct net *net) { - struct sit_net *sitn = net_generic(net, sit_net_id); LIST_HEAD(list); rtnl_lock(); - sit_destroy_tunnels(sitn, &list); + sit_destroy_tunnels(net, &list); unregister_netdevice_many(&list); rtnl_unlock(); } |