From: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Wed, 13 Jul 2022 20:52:05 +0000 (-0700)
Subject: tcp: Fix a data-race around sysctl_tcp_probe_interval.
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=2a85388f1d94a9f8b5a529118a2c5eaa0520d85c;p=linux.git

tcp: Fix a data-race around sysctl_tcp_probe_interval.

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>
---

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index aa757c74dad44..02ab3a9c66574 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2283,7 +2283,7 @@ 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);