[PATCH 5.18 47/88] tcp: Fix a data-race around sysctl_tcp_tso_rtt_log.

Greg Kroah-Hartman
2022-08-01T12:14:30Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit 2455e61b85e9c99af38cd889a7101f1d48b33cb4 ]

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

Fixes: 65466904b015 ("tcp: adjust TSO packet sizes based on min_rtt")
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 08466421e7e0..60c9f7f444e0 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1971,7 +1971,7 @@ static u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now,

bytes = sk->sk_pacing_rate >> READ_ONCE(sk->sk_pacing_shift);

- r = tcp_min_rtt(tcp_sk(sk)) >> sock_net(sk)->ipv4.sysctl_tcp_tso_rtt_log;
+ r = tcp_min_rtt(tcp_sk(sk)) >> READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_tso_rtt_log);
if (r < BITS_PER_TYPE(sk->sk_gso_max_size))
bytes += sk->sk_gso_max_size >> r;

--
2.35.1