netrom: Fix a data-race around sysctl_netrom_obsolescence_count_initialiser

[ Upstream commit cfd9f4a740f772298308b2e6070d2c744fb5cf79 ]

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 94c4d4554b9c7b0f8bbc0d2e774c3b9cd01140a3..8a5375e1dcc77b768fb750faf36e1af19ce3561a 100644 (file)
--- a/net/netrom/nr_route.c
+++ b/net/netrom/nr_route.c
@@ -763,7 +763,7 @@ int nr_route_frame(struct sk_buff *skb, ax25_cb *ax25)
        if (ax25 != NULL) {
                ret = nr_add_node(nr_src, "", &ax25->dest_addr, ax25->digipeat,
                                  ax25->ax25_dev->dev, 0,
-                                 sysctl_netrom_obsolescence_count_initialiser);
+                                 READ_ONCE(sysctl_netrom_obsolescence_count_initialiser));
                if (ret)
                        return ret;
        }