Patch "tcp: annotate data-races around tp->tsoffset" has been added to the 6.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    tcp: annotate data-races around tp->tsoffset

to the 6.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     tcp-annotate-data-races-around-tp-tsoffset.patch
and it can be found in the queue-6.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 5388118e5be93f20f250500b27911813da339615
Author: Eric Dumazet <edumazet@xxxxxxxxxx>
Date:   Wed Jul 19 21:28:48 2023 +0000

    tcp: annotate data-races around tp->tsoffset
    
    [ Upstream commit dd23c9f1e8d5c1d2e3d29393412385ccb9c7a948 ]
    
    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@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20230719212857.3943972-3-edumazet@xxxxxxxxxx
    Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index c0e0add372f75..15b1191411ec3 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3765,7 +3765,7 @@ 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);
@@ -4267,7 +4267,7 @@ 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 5d3e49ceb6917..f37d13ee7b4cc 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();