netfilter: nf_tables: fix memory leak in nf_tables_newrule()

[ Upstream commit d077e81 ]

In nf_tables_newrule(), if nft_use_inc() fails, the function jumps to
the err_release_rule label without freeing the allocated flow, leading
to a memory leak.

Fix this by adding a new label err_destroy_flow and jumping to it when
nft_use_inc() fails. This ensures that the flow is properly released
in this error case.

Fixes: 1689f25 ("netfilter: nf_tables: report use refcount overflow")
Signed-off-by: Zilin Guan <zilin@seu.edu.cn>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: GoodLuck612

net/netfilter/nf_tables_api.c

@@ -4378,7 +4378,7 @@ static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
 
 	if (!nft_use_inc(&chain->use)) {
 		err = -EMFILE;
-		goto err_release_rule;
+		goto err_destroy_flow;
 	}
 
 	if (info->nlh->nlmsg_flags & NLM_F_REPLACE) {
@@ -4428,6 +4428,7 @@ static int nf_tables_newrule(struct sk_buff *skb, const struct nfnl_info *info,
 
 err_destroy_flow_rule:
 	nft_use_dec_restore(&chain->use);
+err_destroy_flow:
 	if (flow)
 		nft_flow_rule_destroy(flow);
 err_release_rule: