[NETFILTER]: nf_conntrack: properly use RCU for nf_conntrack_destroyed callback

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 10 insertions, 6 deletions

diff --git a/net/ipv4/netfilter/nf_nat_core.c b/net/ipv4/netfilter/nf_nat_core.c
index 5156d5d6c3b8..2c01378d3592 100644
--- a/net/ipv4/netfilter/nf_nat_core.c
+++ b/net/ipv4/netfilter/nf_nat_core.c
@@ -617,8 +617,8 @@ static int __init nf_nat_init(void)
         }
 
         /* FIXME: Man, this is a hack.  <SIGH> */
-        NF_CT_ASSERT(nf_conntrack_destroyed == NULL);
-        nf_conntrack_destroyed = &nf_nat_cleanup_conntrack;
+        NF_CT_ASSERT(rcu_dereference(nf_conntrack_destroyed) == NULL);
+        rcu_assign_pointer(nf_conntrack_destroyed, nf_nat_cleanup_conntrack);
 
         /* Initialize fake conntrack so that NAT will skip it */
         nf_conntrack_untracked.status |= IPS_NAT_DONE_MASK;
@@ -642,7 +642,8 @@ static int clean_nat(struct nf_conn *i, void *data)
 static void __exit nf_nat_cleanup(void)
 {
         nf_ct_iterate_cleanup(&clean_nat, NULL);
-        nf_conntrack_destroyed = NULL;
+        rcu_assign_pointer(nf_conntrack_destroyed, NULL);
+        synchronize_rcu();
         vfree(bysource);
         nf_ct_l3proto_put(l3proto);
 }
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index d59640e2377b..0cc150560fb7 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -318,6 +318,7 @@ destroy_conntrack(struct nf_conntrack *nfct)
         struct nf_conn_help *help = nfct_help(ct);
         struct nf_conntrack_l3proto *l3proto;
         struct nf_conntrack_l4proto *l4proto;
+        typeof(nf_conntrack_destroyed) destroyed;
 
         DEBUGP("destroy_conntrack(%p)\n", ct);
         NF_CT_ASSERT(atomic_read(&nfct->use) == 0);
@@ -341,10 +342,12 @@ destroy_conntrack(struct nf_conntrack *nfct)
                                        ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.protonum);
         if (l4proto && l4proto->destroy)
                 l4proto->destroy(ct);
-        rcu_read_unlock();
 
-        if (nf_conntrack_destroyed)
-                nf_conntrack_destroyed(ct);
+        destroyed = rcu_dereference(nf_conntrack_destroyed);
+        if (destroyed)
+                destroyed(ct);
+
+        rcu_read_unlock();
 
         write_lock_bh(&nf_conntrack_lock);
         /* Expectations will have been removed in clean_from_lists,