From 9b134b1694ec8926926ba6b7b80884ea829245a0 Mon Sep 17 00:00:00 2001 From: Benjamin Poirier Date: Mon, 25 Jul 2022 09:12:36 +0900 Subject: [PATCH] bridge: Do not send empty IFLA_AF_SPEC attribute After commit b6c02ef54913 ("bridge: Netlink interface fix."), br_fill_ifinfo() started to send an empty IFLA_AF_SPEC attribute when a bridge vlan dump is requested but an interface does not have any vlans configured. iproute2 ignores such an empty attribute since commit b262a9becbcb ("bridge: Fix output with empty vlan lists") but older iproute2 versions as well as other utilities have their output changed by the cited kernel commit, resulting in failed test cases. Regardless, emitting an empty attribute is pointless and inefficient. Avoid this change by canceling the attribute if no AF_SPEC data was added. Fixes: b6c02ef54913 ("bridge: Netlink interface fix.") Reviewed-by: Ido Schimmel Signed-off-by: Benjamin Poirier Acked-by: Nikolay Aleksandrov Link: https://lore.kernel.org/r/20220725001236.95062-1-bpoirier@nvidia.com Signed-off-by: Paolo Abeni --- net/bridge/br_netlink.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c index bb01776..c96509c 100644 --- a/net/bridge/br_netlink.c +++ b/net/bridge/br_netlink.c @@ -589,9 +589,13 @@ static int br_fill_ifinfo(struct sk_buff *skb, } done: + if (af) { + if (nlmsg_get_pos(skb) - (void *)af > nla_attr_size(0)) + nla_nest_end(skb, af); + else + nla_nest_cancel(skb, af); + } - if (af) - nla_nest_end(skb, af); nlmsg_end(skb, nlh); return 0; -- 2.7.4