[PATCH 5.15 50/69] tcp: Fix a data-race around sysctl_tcp_comp_sack_slack_ns.

Greg Kroah-Hartman
2022-08-01T12:05:18Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit 22396941a7f343d704738360f9ef0e6576489d43 ]

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

Fixes: a70437cc09a1 ("tcp: add hrtimer slack to sack compression")
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 486ca1d5b436..7b593865b4ae 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5517,7 +5517,7 @@ static void __tcp_ack_snd_check(struct sock *sk, int ofo_possible)
rtt * (NSEC_PER_USEC >> 3)/20);
sock_hold(sk);
hrtimer_start_range_ns(&tp->compressed_ack_timer, ns_to_ktime(delay),
- sock_net(sk)->ipv4.sysctl_tcp_comp_sack_slack_ns,
+ READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_comp_sack_slack_ns),
HRTIMER_MODE_REL_PINNED_SOFT);
}

--
2.35.1