From 01267fc7a7723d307baf34992657f1010f2ece61 Mon Sep 17 00:00:00 2001 From: JianJhen Chen Date: Sun, 6 Jan 2019 11:28:13 +0800 Subject: net: bridge: fix a bug on using a neighbour cache entry without checking its state [ Upstream commit 4c84edc11b76590859b1e45dd676074c59602dc4 ] When handling DNAT'ed packets on a bridge device, the neighbour cache entry from lookup was used without checking its state. It means that a cache entry in the NUD_STALE state will be used directly instead of entering the NUD_DELAY state to confirm the reachability of the neighbor. This problem becomes worse after commit 2724680bceee ("neigh: Keep neighbour cache entries if number of them is small enough."), since all neighbour cache entries in the NUD_STALE state will be kept in the neighbour table as long as the number of cache entries does not exceed the value specified in gc_thresh1. This commit validates the state of a neighbour cache entry before using the entry. Signed-off-by: JianJhen Chen Reviewed-by: JinLin Chen Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/bridge/br_netfilter_hooks.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/bridge') diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c index 55dcb2b20b59..6def85d75b1d 100644 --- a/net/bridge/br_netfilter_hooks.c +++ b/net/bridge/br_netfilter_hooks.c @@ -267,7 +267,7 @@ int br_nf_pre_routing_finish_bridge(struct net *net, struct sock *sk, struct sk_ struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); int ret; - if (neigh->hh.hh_len) { + if ((neigh->nud_state & NUD_CONNECTED) && neigh->hh.hh_len) { neigh_hh_bridge(&neigh->hh, skb); skb->dev = nf_bridge->physindev; ret = br_handle_frame_finish(net, sk, skb); -- cgit v1.2.3