[PATCH 4/6] netfilter: nf_tables: add NFTA_SET_USERDATA if not null

[Pablo Neira Ayuso]

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 <pa...@netfilter.org>
---
 net/netfilter/nf_tables_api.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index fd814e514f94..71e501c5ad21 100644
--- 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);
-- 
2.20.1