From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ Upstream commit 3a037f0f3c4bfe44518f2fbb478aa2f99a9cd8bb ]
do_tcp_getsockopt() and reqsk_timer_handler() read
icsk->icsk_syn_retries while another cpu might change its value.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230719212857.3943972-7-edumazet@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/ipv4/inet_connection_sock.c | 2 +-
net/ipv4/tcp.c | 6 +++---
2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 8e35ea66d930a..62a3b103f258a 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -1016,7 +1016,7 @@ static void reqsk_timer_handler(struct timer_list *t)
icsk = inet_csk(sk_listener);
net = sock_net(sk_listener);
- max_syn_ack_retries = icsk->icsk_syn_retries ? :
+ max_syn_ack_retries = READ_ONCE(icsk->icsk_syn_retries) ? :
READ_ONCE(net->ipv4.sysctl_tcp_synack_retries);
/* Normally all the openreqs are young and become mature
* (i.e. converted to established socket) for first timeout.
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 7d75928ea0f9c..ffa9717293358 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3397,7 +3397,7 @@ int tcp_sock_set_syncnt(struct sock *sk, int val)
return -EINVAL;
lock_sock(sk);
- inet_csk(sk)->icsk_syn_retries = val;
+ WRITE_ONCE(inet_csk(sk)->icsk_syn_retries, val);
release_sock(sk);
return 0;
}
@@ -3678,7 +3678,7 @@ int do_tcp_setsockopt(struct sock *sk, int level, int optname,
if (val < 1 || val > MAX_TCP_SYNCNT)
err = -EINVAL;
else
- icsk->icsk_syn_retries = val;
+ WRITE_ONCE(icsk->icsk_syn_retries, val);
break;
case TCP_SAVE_SYN:
@@ -4095,7 +4095,7 @@ int do_tcp_getsockopt(struct sock *sk, int level,
val = keepalive_probes(tp);
break;
case TCP_SYNCNT:
- val = icsk->icsk_syn_retries ? :
+ val = READ_ONCE(icsk->icsk_syn_retries) ? :
READ_ONCE(net->ipv4.sysctl_tcp_syn_retries);
break;
case TCP_LINGER2:
--
2.39.2
