From: Eric Dumazet edumazet@google.com
[ Upstream commit 004db64d185a5f23dfb891d7701e23713b2420ee ]
netlink_getname(), netlink_sendmsg() and netlink_getsockbyportid() can read nlk->dst_portid and nlk->dst_group while another thread is changing them.
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 | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-)
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index f6b985877d9c..d398623d8275 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -1081,8 +1081,9 @@ static int netlink_connect(struct socket *sock, struct sockaddr *addr,
if (addr->sa_family == AF_UNSPEC) { sk->sk_state = NETLINK_UNCONNECTED; - nlk->dst_portid = 0; - nlk->dst_group = 0; + /* dst_portid and dst_group can be read locklessly */ + WRITE_ONCE(nlk->dst_portid, 0); + WRITE_ONCE(nlk->dst_group, 0); return 0; } if (addr->sa_family != AF_NETLINK) @@ -1104,8 +1105,9 @@ static int netlink_connect(struct socket *sock, struct sockaddr *addr,
if (err == 0) { sk->sk_state = NETLINK_CONNECTED; - nlk->dst_portid = nladdr->nl_pid; - nlk->dst_group = ffs(nladdr->nl_groups); + /* 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)); }
return err; @@ -1122,8 +1124,9 @@ static int netlink_getname(struct socket *sock, struct sockaddr *addr, nladdr->nl_pad = 0;
if (peer) { - nladdr->nl_pid = nlk->dst_portid; - nladdr->nl_groups = netlink_group_mask(nlk->dst_group); + /* Paired with WRITE_ONCE() in netlink_connect() */ + nladdr->nl_pid = READ_ONCE(nlk->dst_portid); + nladdr->nl_groups = netlink_group_mask(READ_ONCE(nlk->dst_group)); } else { /* Paired with WRITE_ONCE() in netlink_insert() */ nladdr->nl_pid = READ_ONCE(nlk->portid); @@ -1153,8 +1156,9 @@ 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 && - nlk->dst_portid != nlk_sk(ssk)->portid) { + READ_ONCE(nlk->dst_portid) != nlk_sk(ssk)->portid) { sock_put(sock); return ERR_PTR(-ECONNREFUSED); } @@ -1890,8 +1894,9 @@ static int netlink_sendmsg(struct socket *sock, struct msghdr *msg, size_t len) goto out; netlink_skb_flags |= NETLINK_SKB_DST; } else { - dst_portid = nlk->dst_portid; - dst_group = nlk->dst_group; + /* Paired with WRITE_ONCE() in netlink_connect() */ + dst_portid = READ_ONCE(nlk->dst_portid); + dst_group = READ_ONCE(nlk->dst_group); }
/* Paired with WRITE_ONCE() in netlink_insert() */