Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
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 5.15 077/136] net: Fix a data-race around sysctl_net_busy_poll.
Date:   Mon, 29 Aug 2022 12:59:04 +0200
Message-Id: <20220829105807.795203859@linuxfoundation.org>
In-Reply-To: <20220829105804.609007228@linuxfoundation.org>
References: <20220829105804.609007228@linuxfoundation.org>
User-Agent: quilt/0.67
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit c42b7cddea47503411bfb5f2f93a4154aaffa2d9 ]

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

Fixes: 060212928670 ("net: add low latency socket poll")
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>
---
 include/net/busy_poll.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/net/busy_poll.h b/include/net/busy_poll.h
index 40296ed976a97..3459a04a3d61c 100644
--- a/include/net/busy_poll.h
+++ b/include/net/busy_poll.h
@@ -33,7 +33,7 @@ extern unsigned int sysctl_net_busy_poll __read_mostly;
 
 static inline bool net_busy_loop_on(void)
 {
-	return sysctl_net_busy_poll;
+	return READ_ONCE(sysctl_net_busy_poll);
 }
 
 static inline bool sk_can_busy_loop(const struct sock *sk)
-- 
2.35.1