netlink: annotate data races around sk_state

netlink_getsockbyportid() reads sk_state while a concurrent
netlink_connect() can change its value.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index b5b8c6a..c642776 100644 (file)
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1098,7 +1098,8 @@ static int netlink_connect(struct socket *sock, struct sockaddr *addr,
                return -EINVAL;
 
        if (addr->sa_family == AF_UNSPEC) {
-               sk->sk_state    = NETLINK_UNCONNECTED;
+               /* paired with READ_ONCE() in netlink_getsockbyportid() */
+               WRITE_ONCE(sk->sk_state, NETLINK_UNCONNECTED);
                /* dst_portid and dst_group can be read locklessly */
                WRITE_ONCE(nlk->dst_portid, 0);
                WRITE_ONCE(nlk->dst_group, 0);
@@ -1122,7 +1123,8 @@ static int netlink_connect(struct socket *sock, struct sockaddr *addr,
                err = netlink_autobind(sock);
 
        if (err == 0) {
-               sk->sk_state    = NETLINK_CONNECTED;
+               /* paired with READ_ONCE() in netlink_getsockbyportid() */
+               WRITE_ONCE(sk->sk_state, NETLINK_CONNECTED);
                /* dst_portid and dst_group can be read locklessly */
                WRITE_ONCE(nlk->dst_portid, nladdr->nl_pid);
                WRITE_ONCE(nlk->dst_group, ffs(nladdr->nl_groups));
@@ -1174,8 +1176,8 @@ static struct sock *netlink_getsockbyportid(struct sock *ssk, u32 portid)
 
        /* Don't bother queuing skb if kernel socket has no input function */
        nlk = nlk_sk(sock);
-       /* dst_portid can be changed in netlink_connect() */
-       if (sock->sk_state == NETLINK_CONNECTED &&
+       /* dst_portid and sk_state can be changed in netlink_connect() */
+       if (READ_ONCE(sock->sk_state) == NETLINK_CONNECTED &&
            READ_ONCE(nlk->dst_portid) != nlk_sk(ssk)->portid) {
                sock_put(sock);
                return ERR_PTR(-ECONNREFUSED);