[PATCH 5.10 048/105] tcp: Fix data-races around keepalive sysctl knobs.

[Greg Kroah-Hartman]

From: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>

[ Upstream commit f2f316e287e6c2e3a1c5bab8d9b77ee03daa0463 ]

While reading sysctl_tcp_keepalive_(time|probes|intvl), they can be changed
concurrently.  Thus, we need to add READ_ONCE() to their readers.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 include/net/tcp.h | 9 ++++++---
 net/smc/smc_llc.c | 2 +-
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 2a28e0925573..9ef9fd0677b5 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1447,21 +1447,24 @@ static inline int keepalive_intvl_when(const struct tcp_sock *tp)
 {
 	struct net *net = sock_net((struct sock *)tp);
 
-	return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl;
+	return tp->keepalive_intvl ? :
+		READ_ONCE(net->ipv4.sysctl_tcp_keepalive_intvl);
 }
 
 static inline int keepalive_time_when(const struct tcp_sock *tp)
 {
 	struct net *net = sock_net((struct sock *)tp);
 
-	return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time;
+	return tp->keepalive_time ? :
+		READ_ONCE(net->ipv4.sysctl_tcp_keepalive_time);
 }
 
 static inline int keepalive_probes(const struct tcp_sock *tp)
 {
 	struct net *net = sock_net((struct sock *)tp);
 
-	return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes;
+	return tp->keepalive_probes ? :
+		READ_ONCE(net->ipv4.sysctl_tcp_keepalive_probes);
 }
 
 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
diff --git a/net/smc/smc_llc.c b/net/smc/smc_llc.c
index ee1f0fdba085..0ef15f8fba90 100644
--- a/net/smc/smc_llc.c
+++ b/net/smc/smc_llc.c
@@ -1787,7 +1787,7 @@ void smc_llc_lgr_init(struct smc_link_group *lgr, struct smc_sock *smc)
 	init_waitqueue_head(&lgr->llc_flow_waiter);
 	init_waitqueue_head(&lgr->llc_msg_waiter);
 	mutex_init(&lgr->llc_conf_mutex);
-	lgr->llc_testlink_time = net->ipv4.sysctl_tcp_keepalive_time;
+	lgr->llc_testlink_time = READ_ONCE(net->ipv4.sysctl_tcp_keepalive_time);
 }
 
 /* called after lgr was removed from lgr_list */
-- 
2.35.1