[PATCH 5.18 047/158] tcp: Fix a data-race around sysctl_tcp_probe_interval.

Greg Kroah-Hartman
2022-07-27T17:33:10Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit 2a85388f1d94a9f8b5a529118a2c5eaa0520d85c ]

While reading sysctl_tcp_probe_interval, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its reader.

Fixes: 05cbc0db03e8 ("ipv4: Create probe timer for tcp PMTU as per RFC4821")
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>
---
net/ipv4/tcp_output.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 4057da397087..99a2f4518e2e 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2281,7 +2281,7 @@ static inline void tcp_mtu_check_reprobe(struct sock *sk)
u32 interval;
s32 delta;

- interval = net->ipv4.sysctl_tcp_probe_interval;
+ interval = READ_ONCE(net->ipv4.sysctl_tcp_probe_interval);
delta = tcp_jiffies32 - icsk->icsk_mtup.probe_timestamp;
if (unlikely(delta >= interval * HZ)) {
int mss = tcp_current_mss(sk);
--
2.35.1