[NETFILTER]: ip_conntrack: properly use RCU for ip_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/ip_conntrack_core.c b/net/ipv4/netfilter/ip_conntrack_core.c
index a7e34d007ab0..07ba1dd136b5 100644
--- a/net/ipv4/netfilter/ip_conntrack_core.c
+++ b/net/ipv4/netfilter/ip_conntrack_core.c
@@ -303,6 +303,7 @@ destroy_conntrack(struct nf_conntrack *nfct)
         struct ip_conntrack *ct = (struct ip_conntrack *)nfct;
         struct ip_conntrack_protocol *proto;
         struct ip_conntrack_helper *helper;
+        typeof(ip_conntrack_destroyed) destroyed;
 
         DEBUGP("destroy_conntrack(%p)\n", ct);
         IP_NF_ASSERT(atomic_read(&nfct->use) == 0);
@@ -322,10 +323,12 @@ destroy_conntrack(struct nf_conntrack *nfct)
         proto = __ip_conntrack_proto_find(ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.protonum);
         if (proto && proto->destroy)
                 proto->destroy(ct);
-        rcu_read_unlock();
 
-        if (ip_conntrack_destroyed)
-                ip_conntrack_destroyed(ct);
+        destroyed = rcu_dereference(ip_conntrack_destroyed);
+        if (destroyed)
+                destroyed(ct);
+
+        rcu_read_unlock();
 
         write_lock_bh(&ip_conntrack_lock);
         /* Expectations will have been removed in clean_from_lists,
diff --git a/net/ipv4/netfilter/ip_nat_core.c b/net/ipv4/netfilter/ip_nat_core.c
index 18daabc22069..40737fdbe9a7 100644
--- a/net/ipv4/netfilter/ip_nat_core.c
+++ b/net/ipv4/netfilter/ip_nat_core.c
@@ -604,8 +604,8 @@ static int __init ip_nat_init(void)
         }
 
         /* FIXME: Man, this is a hack.  <SIGH> */
-        IP_NF_ASSERT(ip_conntrack_destroyed == NULL);
-        ip_conntrack_destroyed = &ip_nat_cleanup_conntrack;
+        IP_NF_ASSERT(rcu_dereference(ip_conntrack_destroyed) == NULL);
+        rcu_assign_pointer(ip_conntrack_destroyed, ip_nat_cleanup_conntrack);
 
         /* Initialize fake conntrack so that NAT will skip it */
         ip_conntrack_untracked.status |= IPS_NAT_DONE_MASK;
@@ -623,7 +623,8 @@ static int clean_nat(struct ip_conntrack *i, void *data)
 static void __exit ip_nat_cleanup(void)
 {
         ip_ct_iterate_cleanup(&clean_nat, NULL);
-        ip_conntrack_destroyed = NULL;
+        rcu_assign_pointer(ip_conntrack_destroyed, NULL);
+        synchronize_rcu();
         vfree(bysource);
 }