tcp: annotate data-races around tp->tsoffset

do_tcp_getsockopt() reads tp->tsoffset while another cpu
might change its value.

Fixes: 93be6ce0e91b ("tcp: set and get per-socket timestamp")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20230719212857.3943972-3-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index bd6400e..03ae655 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3656,7 +3656,7 @@ int do_tcp_setsockopt(struct sock *sk, int level, int optname,
                if (!tp->repair)
                        err = -EPERM;
                else
-                       tp->tsoffset = val - tcp_time_stamp_raw();
+                       WRITE_ONCE(tp->tsoffset, val - tcp_time_stamp_raw());
                break;
        case TCP_REPAIR_WINDOW:
                err = tcp_repair_set_window(tp, optval, optlen);
@@ -4158,7 +4158,7 @@ int do_tcp_getsockopt(struct sock *sk, int level,
                break;
 
        case TCP_TIMESTAMP:
-               val = tcp_time_stamp_raw() + tp->tsoffset;
+               val = tcp_time_stamp_raw() + READ_ONCE(tp->tsoffset);
                break;
        case TCP_NOTSENT_LOWAT:
                val = tp->notsent_lowat;

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index b5c81cf..0696420 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -307,8 +307,9 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
                                                  inet->inet_daddr,
                                                  inet->inet_sport,
                                                  usin->sin_port));
-               tp->tsoffset = secure_tcp_ts_off(net, inet->inet_saddr,
-                                                inet->inet_daddr);
+               WRITE_ONCE(tp->tsoffset,
+                          secure_tcp_ts_off(net, inet->inet_saddr,
+                                            inet->inet_daddr));
        }
 
        inet->inet_id = get_random_u16();