netfilter: ctnetlink: fix return value of ctnetlink_get_expect()

This fixes one bogus error that is returned to user-space:

libnetfilter_conntrack/utils# ./expect_get
TEST: get expectation (-1)(Unknown error 18446744073709551504)

This patch includes the correct handling for EAGAIN (nfnetlink
uses this error value to restart the operation after module
auto-loading).

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

1 files changed, 10 insertions, 5 deletions

diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index ef21b221f036..3d7ea7af76fc 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -1869,25 +1869,30 @@ ctnetlink_get_expect(struct sock *ctnl, struct sk_buff *skb,
 
         err = -ENOMEM;
         skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
-        if (skb2 == NULL)
+        if (skb2 == NULL) {
+                nf_ct_expect_put(exp);
                 goto out;
+        }
 
         rcu_read_lock();
         err = ctnetlink_exp_fill_info(skb2, NETLINK_CB(skb).pid,
                                       nlh->nlmsg_seq, IPCTNL_MSG_EXP_NEW, exp);
         rcu_read_unlock();
+        nf_ct_expect_put(exp);
         if (err <= 0)
                 goto free;
 
-        nf_ct_expect_put(exp);
+        err = netlink_unicast(ctnl, skb2, NETLINK_CB(skb).pid, MSG_DONTWAIT);
+        if (err < 0)
+                goto out;
 
-        return netlink_unicast(ctnl, skb2, NETLINK_CB(skb).pid, MSG_DONTWAIT);
+        return 0;
 
 free:
         kfree_skb(skb2);
 out:
-        nf_ct_expect_put(exp);
-        return err;
+        /* this avoids a loop in nfnetlink. */
+        return err == -EAGAIN ? -ENOBUFS : err;
 }
 
 static int