[PATCH 4.14 57/91] netfilter: nf_queue: enqueue skbs with NULL dst

From: Greg Kroah-Hartman
Date: Thu Jan 02 2020 - 17:26:34 EST

From: Marco Oliverio <marco.oliverio@xxxxxxxxxx>

[ Upstream commit 0b9173f4688dfa7c5d723426be1d979c24ce3d51 ]

Bridge packets that are forwarded have skb->dst == NULL and get
dropped by the check introduced by
b60a77386b1d4868f72f6353d35dabe5fbe981f2 (net: make skb_dst_force
return true when dst is refcounted).

To fix this we check skb_dst() before skb_dst_force(), so we don't
drop skb packet with dst == NULL. This holds also for skb at the
PRE_ROUTING hook so we remove the second check.

Fixes: b60a77386b1d ("net: make skb_dst_force return true when dst is refcounted")
Signed-off-by: Marco Oliverio <marco.oliverio@xxxxxxxxxx>
Signed-off-by: Rocco Folino <rocco.folino@xxxxxxxxxx>
Acked-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
net/netfilter/nf_queue.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/nf_queue.c b/net/netfilter/nf_queue.c
index 37efcc1c8887..b06ef4c62522 100644
--- a/net/netfilter/nf_queue.c
+++ b/net/netfilter/nf_queue.c
@@ -138,7 +138,7 @@ static int __nf_queue(struct sk_buff *skb, const struct nf_hook_state *state,
goto err;

- if (!skb_dst_force(skb) && state->hook != NF_INET_PRE_ROUTING) {
+ if (skb_dst(skb) && !skb_dst_force(skb)) {
status = -ENETDOWN;
goto err;