tcp: Fix a data-race around sysctl_tcp_probe_interval.

[ Upstream commit 6dbd108d836100ed8fcdaa08592279a5ee0be9ab ]

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

Fixes: e310122afc00 ("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>

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index e60cb69d00a4cbab53c395fcb6b3899e598d2536..9bfe6965b873c888984395a1f6dd628910a83097 100644 (file)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2052,7 +2052,7 @@ 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);