From:   Xin Xiong <xiongx18@fudan.edu.cn>
To:     Pablo Neira Ayuso <pablo@netfilter.org>,
        Jozsef Kadlecsik <kadlec@netfilter.org>,
        Florian Westphal <fw@strlen.de>,
        "David S . Miller" <davem@davemloft.net>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        David Ahern <dsahern@kernel.org>,
        Jakub Kicinski <kuba@kernel.org>,
        netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     yuanxzhang@fudan.edu.cn, Xin Xiong <xiongx18@fudan.edu.cn>,
        Xiyu Yang <xiyuyang19@fudan.edu.cn>,
        Xin Tan <tanxin.ctf@gmail.com>
Subject: [PATCH] netfilter: ipt_CLUSTERIP: fix refcount leak in clusterip_tg_check()
Date:   Thu, 23 Dec 2021 10:48:12 +0800
Message-Id: <20211223024811.4519-1-xiongx18@fudan.edu.cn>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

The issue takes place in one error path of clusterip_tg_check(). When
memcmp() returns nonzero, the function simply returns the error code,
forgetting to decrease the reference count of a clusterip_config
object, which is bumped earlier by clusterip_config_find_get(). This
may incur reference count leak.

Fix this issue by decrementing the refcount of the object in specific
error path.

Signed-off-by: Xin Xiong <xiongx18@fudan.edu.cn>
Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
---
 net/ipv4/netfilter/ipt_CLUSTERIP.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c
index 8fd1aba8a..b518f20c9 100644
--- a/net/ipv4/netfilter/ipt_CLUSTERIP.c
+++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c
@@ -520,8 +520,11 @@ static int clusterip_tg_check(const struct xt_tgchk_param *par)
 			if (IS_ERR(config))
 				return PTR_ERR(config);
 		}
-	} else if (memcmp(&config->clustermac, &cipinfo->clustermac, ETH_ALEN))
+	} else if (memcmp(&config->clustermac, &cipinfo->clustermac, ETH_ALEN)) {
+		clusterip_config_entry_put(config);
+		clusterip_config_put(config);
 		return -EINVAL;
+	}
 
 	ret = nf_ct_netns_get(par->net, par->family);
 	if (ret < 0) {
-- 
2.25.1