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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Kuniyuki Iwashima <kuniyu@amazon.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 31/62] tcp: Fix a data-race around sysctl_tcp_rfc1337.
Date:   Wed, 27 Jul 2022 18:10:40 +0200
Message-Id: <20220727161005.433650475@linuxfoundation.org>
In-Reply-To: <20220727161004.175638564@linuxfoundation.org>
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From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit 0b484c91911e758e53656d570de58c2ed81ec6f2 ]

While reading sysctl_tcp_rfc1337, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its reader.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
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_minisocks.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index c79cb949da66..0fc238d79b03 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -179,7 +179,7 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
 			 * Oh well... nobody has a sufficient solution to this
 			 * protocol bug yet.
 			 */
-			if (twsk_net(tw)->ipv4.sysctl_tcp_rfc1337 == 0) {
+			if (!READ_ONCE(twsk_net(tw)->ipv4.sysctl_tcp_rfc1337)) {
 kill:
 				inet_twsk_deschedule_put(tw);
 				return TCP_TW_SUCCESS;
-- 
2.35.1