From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ Upstream commit 9b663b5cbb15b494ef132a3c937641c90646eb73 ]
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@xxxxxxxxxx>
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/netlink/af_netlink.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 1547d0825668..d7b0a7aa29a8 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1061,7 +1061,8 @@ 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);
@@ -1085,7 +1086,8 @@ 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));
@@ -1137,8 +1139,8 @@ 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);
--
2.39.0
