From: Eric Dumazet edumazet@google.com
[ 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@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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);