diff options
| author | Kirill Tkhai <ktkhai@virtuozzo.com> | 2017-11-14 16:51:56 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-11-15 14:01:30 +0900 |
| commit | 11bf284f81b46f59d5f4a4522c13aa7852cfd560 (patch) | |
| tree | ef75ac5dfa27442a19b463937088e7f2eeca87fb /net | |
| parent | 094009531612246d9e13f9e0c3ae2205d7f63a0a (diff) | |
net: Protect iterations over net::fib_notifier_ops in fib_seq_sum()
There is at least unlocked deletion of net->ipv4.fib_notifier_ops
from net::fib_notifier_ops:
ip_fib_net_exit()
rtnl_unlock()
fib4_notifier_exit()
fib_notifier_ops_unregister(net->ipv4.notifier_ops)
list_del_rcu(&ops->list)
So fib_seq_sum() can't use rtnl_lock() only for protection.
The possible solution could be to use rtnl_lock()
in fib_notifier_ops_unregister(), but this adds
a possible delay during net namespace creation,
so we better use rcu_read_lock() till someone
really needs the mutex (if that happens).
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/core/fib_notifier.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/net/core/fib_notifier.c b/net/core/fib_notifier.c index 6b8cd494574f..0c048bdeb016 100644 --- a/net/core/fib_notifier.c +++ b/net/core/fib_notifier.c @@ -34,12 +34,14 @@ static unsigned int fib_seq_sum(void) rtnl_lock(); for_each_net(net) { - list_for_each_entry(ops, &net->fib_notifier_ops, list) { + rcu_read_lock(); + list_for_each_entry_rcu(ops, &net->fib_notifier_ops, list) { if (!try_module_get(ops->owner)) continue; fib_seq += ops->fib_seq_read(net); module_put(ops->owner); } + rcu_read_unlock(); } rtnl_unlock(); |