[PATCH 5.18 48/88] tcp: Fix a data-race around sysctl_tcp_min_rtt_wlen.

Greg Kroah-Hartman
2022-08-01T12:14:39Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit 1330ffacd05fc9ac4159d19286ce119e22450ed2 ]

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

Fixes: f672258391b4 ("tcp: track min RTT using windowed min-filter")
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_input.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 78e16891f12b..f3b658fa3e7b 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3058,7 +3058,7 @@ static void tcp_fastretrans_alert(struct sock *sk, const u32 prior_snd_una,

static void tcp_update_rtt_min(struct sock *sk, u32 rtt_us, const int flag)
{
- u32 wlen = sock_net(sk)->ipv4.sysctl_tcp_min_rtt_wlen * HZ;
+ u32 wlen = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_min_rtt_wlen) * HZ;
struct tcp_sock *tp = tcp_sk(sk);

if ((flag & FLAG_ACK_MAYBE_DELAYED) && rtt_us > tcp_min_rtt(tp)) {
--
2.35.1