netdev - [PATCH net 02/11] tcp: annotate data-races around tp->tsoffset

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Message-ID: <20230719212857.3943972-3-edumazet@google.com>
Date: Wed, 19 Jul 2023 21:28:48 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net 02/11] 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@...gle.com>
---
 net/ipv4/tcp.c      | 4 ++--
 net/ipv4/tcp_ipv4.c | 5 +++--
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index bd6400e1ae9f8ae595bbe759ff3dfb1bd02765e2..03ae6554c78d1e42894a8e511cef362134660aac 100644
--- 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 b5c81cf5b86f7cb086c9c9619dec0c088e5d5916..0696420146369a8786f0dbab142e45aa09fbac00 100644
--- 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();
-- 
2.41.0.255.g8b1d071c50-goog