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Message-Id: <20220809175513.421710176@linuxfoundation.org>
Date: Tue, 9 Aug 2022 20:00:01 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Kuniyuki Iwashima <kuniyu@...zon.com>,
"David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.19 10/32] tcp: Fix a data-race around sysctl_tcp_challenge_ack_limit.
From: Kuniyuki Iwashima <kuniyu@...zon.com>
commit db3815a2fa691da145cfbe834584f31ad75df9ff upstream.
While reading sysctl_tcp_challenge_ack_limit, it can be changed
concurrently. Thus, we need to add READ_ONCE() to its reader.
Fixes: 282f23c6ee34 ("tcp: implement RFC 5961 3.2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
net/ipv4/tcp_input.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3468,7 +3468,7 @@ static void tcp_send_challenge_ack(struc
/* Then check host-wide RFC 5961 rate limit. */
now = jiffies / HZ;
if (now != challenge_timestamp) {
- u32 ack_limit = net->ipv4.sysctl_tcp_challenge_ack_limit;
+ u32 ack_limit = READ_ONCE(net->ipv4.sysctl_tcp_challenge_ack_limit);
u32 half = (ack_limit + 1) >> 1;
challenge_timestamp = now;
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