inet: fix races in reqsk_queue_hash_req()

Before allowing lockless LISTEN processing, we need to make
sure to arm the SYN_RECV timer before the req socket is visible
in hash tables.

Also, req->rsk_hash should be written before we set rsk_refcnt
to a non zero value.

Fixes: fa76ce7328b2 ("inet: get rid of central tcp/dccp listener timer")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Ying Cai <ycai@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 134957159c27eb9180e08b73360fe891574b4742..7bb9c39e0a4d1a6a30b7aece9d3b0c17e447c20a 100644 (file)
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -685,20 +685,20 @@ void reqsk_queue_hash_req(struct request_sock_queue *queue,
        req->num_timeout = 0;
        req->sk = NULL;
 
+       setup_timer(&req->rsk_timer, reqsk_timer_handler, (unsigned long)req);
+       mod_timer_pinned(&req->rsk_timer, jiffies + timeout);
+       req->rsk_hash = hash;
+
        /* before letting lookups find us, make sure all req fields
         * are committed to memory and refcnt initialized.
         */
        smp_wmb();
        atomic_set(&req->rsk_refcnt, 2);
-       setup_timer(&req->rsk_timer, reqsk_timer_handler, (unsigned long)req);
-       req->rsk_hash = hash;
 
        spin_lock(&queue->syn_wait_lock);
        req->dl_next = lopt->syn_table[hash];
        lopt->syn_table[hash] = req;
        spin_unlock(&queue->syn_wait_lock);
-
-       mod_timer_pinned(&req->rsk_timer, jiffies + timeout);
 }
 EXPORT_SYMBOL(reqsk_queue_hash_req);