netfilter: nf_tables: fix a missing check of nla_put_failure

[ Upstream commit eb8950861c1bfd3eecc8f6faad213e3bca0dc395 ]

If nla_nest_start() may fail. The fix checks its return value and goes
to nla_put_failure if it fails.
Signed-off-by: NKangjie Lu <kjlu@umn.edu>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>

net/netfilter/nf_tables_api.c

@@ -5737,6 +5737,8 @@ static int nf_tables_fill_flowtable_info(struct sk_buff *skb, struct net *net,
 		goto nla_put_failure;
 
 	nest = nla_nest_start(skb, NFTA_FLOWTABLE_HOOK);
+	if (!nest)
+		goto nla_put_failure;
 	if (nla_put_be32(skb, NFTA_FLOWTABLE_HOOK_NUM, htonl(flowtable->hooknum)) ||
 	    nla_put_be32(skb, NFTA_FLOWTABLE_HOOK_PRIORITY, htonl(flowtable->priority)))
 		goto nla_put_failure;