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 aa757c7..02ab3a9 100644 (file)
--- 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);