netfilter: nf_tables: add NFTA_SET_USERDATA if not null

Kernel sends an empty NFTA_SET_USERDATA attribute with no value if
userspace adds a set with no NFTA_SET_USERDATA attribute.

Fixes: e6d8ecac9e68 ("netfilter: nf_tables: Add new attributes into nft_set to store user data.")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index fd814e5..71e501c 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -3770,7 +3770,8 @@ static int nf_tables_fill_set(struct sk_buff *skb, const struct nft_ctx *ctx,
                        goto nla_put_failure;
        }
 
-       if (nla_put(skb, NFTA_SET_USERDATA, set->udlen, set->udata))
+       if (set->udata &&
+           nla_put(skb, NFTA_SET_USERDATA, set->udlen, set->udata))
                goto nla_put_failure;
 
        nest = nla_nest_start_noflag(skb, NFTA_SET_DESC);