netfilter: ctnetlink: fix scheduling while atomic if helper is autoloaded

This patch fixes one scheduling while atomic error:

[  385.565186] ctnetlink v0.93: registering with nfnetlink.
[  385.565349] BUG: scheduling while atomic: lt-expect_creat/16163/0x00000200

It can be triggered with utils/expect_create included in
libnetfilter_conntrack if the FTP helper is not loaded.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index 3d7ea7af76fc..b6977776d715 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -1358,12 +1358,15 @@ ctnetlink_create_conntrack(struct net *net, u16 zone,
                                                     nf_ct_protonum(ct));
                 if (helper == NULL) {
                         rcu_read_unlock();
+                        spin_unlock_bh(&nf_conntrack_lock);
 #ifdef CONFIG_MODULES
                         if (request_module("nfct-helper-%s", helpname) < 0) {
+                                spin_lock_bh(&nf_conntrack_lock);
                                 err = -EOPNOTSUPP;
                                 goto err1;
                         }
 
+                        spin_lock_bh(&nf_conntrack_lock);
                         rcu_read_lock();
                         helper = __nf_conntrack_helper_find(helpname,
                                                             nf_ct_l3num(ct),