bridge: dont send notification when skb->len == 0 in rtnl_bridge_notify

commit 59ccaaaa49b5b096cdc1f16706a9f931416b2332 upstream.

Reported in: https://bugzilla.kernel.org/show_bug.cgi?id=92081

This patch avoids calling rtnl_notify if the device ndo_bridge_getlink
handler does not return any bytes in the skb.

Alternately, the skb->len check can be moved inside rtnl_notify.

For the bridge vlan case described in 92081, there is also a fix needed
in bridge driver to generate a proper notification. Will fix that in
subsequent patch.

v2: rebase patch on net tree

Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 48c2be43f856d132843bada3b95c77f128bf077b..2128423f8a7cc9790d3951ae5ee15ada6ec7aa45 100644 (file)
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -2690,12 +2690,16 @@ static int rtnl_bridge_notify(struct net_device *dev, u16 flags)
                        goto errout;
        }
 
+       if (!skb->len)
+               goto errout;
+
        rtnl_notify(skb, net, 0, RTNLGRP_LINK, NULL, GFP_ATOMIC);
        return 0;
 errout:
        WARN_ON(err == -EMSGSIZE);
        kfree_skb(skb);
-       rtnl_set_sk_err(net, RTNLGRP_LINK, err);
+       if (err)
+               rtnl_set_sk_err(net, RTNLGRP_LINK, err);
        return err;
 }