From: Jason Xing <kernelxing@tencent.com>
Date: Mon, 4 Mar 2024 08:20:44 +0000 (+0800)
Subject: netrom: Fix a data-race around sysctl_netrom_routing_control
X-Git-Tag: v6.6.22~12
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d732b83251322ecd3b503e03442247745d6052ce;p=thirdparty%2Fkernel%2Fstable.git

netrom: Fix a data-race around sysctl_netrom_routing_control

[ 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>
---

diff --git a/net/netrom/nr_route.c b/net/netrom/nr_route.c
index b8ddd8048f352..89e12e6eea2ef 100644
--- a/net/netrom/nr_route.c
+++ b/net/netrom/nr_route.c
@@ -780,7 +780,7 @@ 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 */