[PATCH 5.18 066/158] tcp: Fix data-races around keepalive sysctl knobs.

Greg Kroah-Hartman
2022-07-27T17:39:51Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ 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@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 113ce516ce42..e6f9a02fa465 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1511,21 +1511,24 @@ 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 c4d057b2941d..0bde36b56472 100644
--- a/net/smc/smc_llc.c
+++ b/net/smc/smc_llc.c
@@ -2122,7 +2122,7 @@ 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