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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Cc: Jason Xing <kernelxing@tencent.com>,
	Paolo Abeni <pabeni@redhat.com>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.4 22/51] netrom: Fix a data-race around sysctl_netrom_routing_control
Date: Wed, 13 Mar 2024 13:01:43 -0400
Message-ID: <20240313170212.616443-23-sashal@kernel.org>
In-Reply-To: <20240313170212.616443-1-sashal@kernel.org>
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From: Jason Xing <kernelxing@tencent.com>

[ Upstream commit b5dffcb8f71bdd02a4e5799985b51b12f4eeaf76 ]

We need to protect the reader reading the sysctl value because the
value can be changed concurrently.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Jason Xing <kernelxing@tencent.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/netrom/nr_route.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netrom/nr_route.c b/net/netrom/nr_route.c
index 7859217249124..4fb5959a7f070 100644
--- a/net/netrom/nr_route.c
+++ b/net/netrom/nr_route.c
@@ -777,7 +777,7 @@ int nr_route_frame(struct sk_buff *skb, ax25_cb *ax25)
 		return ret;
 	}
 
-	if (!sysctl_netrom_routing_control && ax25 != NULL)
+	if (!READ_ONCE(sysctl_netrom_routing_control) && ax25 != NULL)
 		return 0;
 
 	/* Its Time-To-Live has expired */
-- 
2.43.0