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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 5.10 032/105] ip: Fix a data-race around sysctl_ip_autobind_reuse.
Date:   Wed, 27 Jul 2022 18:10:18 +0200
Message-Id: <20220727161013.379136661@linuxfoundation.org>
In-Reply-To: <20220727161012.056867467@linuxfoundation.org>
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From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit 0db232765887d9807df8bcb7b6f29b2871539eab ]

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

Fixes: 4b01a9674231 ("tcp: bind(0) remove the SO_REUSEADDR restriction when ephemeral ports are exhausted.")
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/inet_connection_sock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 7785a4775e58..4d9713324003 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -251,7 +251,7 @@ inet_csk_find_open_port(struct sock *sk, struct inet_bind_bucket **tb_ret, int *
 		goto other_half_scan;
 	}
 
-	if (net->ipv4.sysctl_ip_autobind_reuse && !relax) {
+	if (READ_ONCE(net->ipv4.sysctl_ip_autobind_reuse) && !relax) {
 		/* We still have a chance to connect to different destinations */
 		relax = true;
 		goto ports_exhausted;
-- 
2.35.1