tipc: Fix tipc_sk_reinit race conditions

There are two problems with the function tipc_sk_reinit.  Firstly
it's doing a manual walk over an rhashtable.  This is broken as
an rhashtable can be resized and if you manually walk over it
during a resize then you may miss entries.

Secondly it's missing memory barriers as previously the code used
spinlocks which provide the barriers implicitly.

This patch fixes both problems.

Fixes: 07f6c4bc048a ("tipc: convert tipc reference table to...")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 23 insertions, 11 deletions

diff --git a/net/tipc/net.c b/net/tipc/net.c
index 28bf4feeb81c..ab8a2d5d1e32 100644
--- a/net/tipc/net.c
+++ b/net/tipc/net.c
@@ -110,6 +110,10 @@ int tipc_net_start(struct net *net, u32 addr)
         char addr_string[16];
 
         tn->own_addr = addr;
+
+        /* Ensure that the new address is visible before we reinit. */
+        smp_mb();
+
         tipc_named_reinit(net);
         tipc_sk_reinit(net);
 
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 103d1fd058c0..6b09a778cc71 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -430,8 +430,6 @@ static int tipc_sk_create(struct net *net, struct socket *sock,
         INIT_LIST_HEAD(&tsk->cong_links);
         msg = &tsk->phdr;
         tn = net_generic(sock_net(sk), tipc_net_id);
-        tipc_msg_init(tn->own_addr, msg, TIPC_LOW_IMPORTANCE, TIPC_NAMED_MSG,
-                      NAMED_H_SIZE, 0);
 
         /* Finish initializing socket data structures */
         sock->ops = ops;
@@ -441,6 +439,13 @@ static int tipc_sk_create(struct net *net, struct socket *sock,
                 pr_warn("Socket create failed; port number exhausted\n");
                 return -EINVAL;
         }
+
+        /* Ensure tsk is visible before we read own_addr. */
+        smp_mb();
+
+        tipc_msg_init(tn->own_addr, msg, TIPC_LOW_IMPORTANCE, TIPC_NAMED_MSG,
+                      NAMED_H_SIZE, 0);
+
         msg_set_origport(msg, tsk->portid);
         setup_timer(&sk->sk_timer, tipc_sk_timeout, (unsigned long)tsk);
         sk->sk_shutdown = 0;
@@ -2234,24 +2239,27 @@ static int tipc_sk_withdraw(struct tipc_sock *tsk, uint scope,
 void tipc_sk_reinit(struct net *net)
 {
         struct tipc_net *tn = net_generic(net, tipc_net_id);
-        const struct bucket_table *tbl;
-        struct rhash_head *pos;
+        struct rhashtable_iter iter;
         struct tipc_sock *tsk;
         struct tipc_msg *msg;
-        int i;
 
-        rcu_read_lock();
-        tbl = rht_dereference_rcu((&tn->sk_rht)->tbl, &tn->sk_rht);
-        for (i = 0; i < tbl->size; i++) {
-                rht_for_each_entry_rcu(tsk, pos, tbl, i, node) {
+        rhashtable_walk_enter(&tn->sk_rht, &iter);
+
+        do {
+                tsk = ERR_PTR(rhashtable_walk_start(&iter));
+                if (tsk)
+                        continue;
+
+                while ((tsk = rhashtable_walk_next(&iter)) && !IS_ERR(tsk)) {
                         spin_lock_bh(&tsk->sk.sk_lock.slock);
                         msg = &tsk->phdr;
                         msg_set_prevnode(msg, tn->own_addr);
                         msg_set_orignode(msg, tn->own_addr);
                         spin_unlock_bh(&tsk->sk.sk_lock.slock);
                 }
-        }
-        rcu_read_unlock();
+
+                rhashtable_walk_stop(&iter);
+        } while (tsk == ERR_PTR(-EAGAIN));
 }
 
 static struct tipc_sock *tipc_sk_lookup(struct net *net, u32 portid)