[PATCH v2] bridge: dont send notification when skb->len == 0 in rtnl_bridge_notify

[PATCH v2] bridge: dont send notification when skb->len == 0 in rtnl_bridge_notify

[roopa]

From: Roopa Prabhu <roopa@cumulusnetworks.com>

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>
---
 net/core/rtnetlink.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 9cf6fe9..446cbaf 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -2895,12 +2895,16 @@ 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;
 }
 
-- 
1.7.10.4

Re: [PATCH v2] bridge: dont send notification when skb->len == 0 in rtnl_bridge_notify

[David Miller]

From: roopa@cumulusnetworks.com
Date: Wed, 28 Jan 2015 16:23:11 -0800

> From: Roopa Prabhu <roopa@cumulusnetworks.com>
> 
> 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>

Applied, thanks.