netfilter: nf_flow_table: fix netdev refcnt leak

flow_offload_alloc() calls nf_route() to get a dst_entry. Internally,
nf_route() calls ip_route_output_key() that allocates a dst_entry and
holds it. So, a dst_entry should be released by dst_release() if
nf_route() is successful.

Otherwise, netns exit routine cannot be finished and the following
message is printed:

[  257.490952] unregister_netdevice: waiting for lo to become free. Usage count = 1

Fixes: ac2a66665e23 ("netfilter: add generic flow table infrastructure")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nft_flow_offload.c b/net/netfilter/nft_flow_offload.c
index 8968c7f..69d7a84 100644 (file)
--- a/net/netfilter/nft_flow_offload.c
+++ b/net/netfilter/nft_flow_offload.c
@@ -112,6 +112,7 @@ static void nft_flow_offload_eval(const struct nft_expr *expr,
        if (ret < 0)
                goto err_flow_add;
 
+       dst_release(route.tuple[!dir].dst);
        return;
 
 err_flow_add: