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From:   Kuniyuki Iwashima <kuniyu@amazon.com>
To:     "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>
CC:     Kuniyuki Iwashima <kuniyu@amazon.com>,
        Kuniyuki Iwashima <kuni1840@gmail.com>,
        <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        Willem de Bruijn <willemb@google.com>
Subject: [PATCH v1 net 11/15] net: Fix a data-race around sysctl_tstamp_allow_data.
Date:   Mon, 15 Aug 2022 22:23:43 -0700
Message-ID: <20220816052347.70042-12-kuniyu@amazon.com>
In-Reply-To: <20220816052347.70042-1-kuniyu@amazon.com>
References: <20220816052347.70042-1-kuniyu@amazon.com>
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While reading sysctl_tstamp_allow_data, it can be changed
concurrently.  Thus, we need to add READ_ONCE() to its reader.

Fixes: b245be1f4db1 ("net-timestamp: no-payload only sysctl")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
CC: Willem de Bruijn <willemb@google.com>
---
 net/core/skbuff.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 974bbbbe7138..174f34124c06 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -4798,7 +4798,7 @@ static bool skb_may_tx_timestamp(struct sock *sk, bool tsonly)
 {
 	bool ret;
 
-	if (likely(sysctl_tstamp_allow_data || tsonly))
+	if (likely(READ_ONCE(sysctl_tstamp_allow_data) || tsonly))
 		return true;
 
 	read_lock_bh(&sk->sk_callback_lock);
-- 
2.30.2