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

Xin Xiong <xiongx18@fudan.edu.cn> wrote:
> 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.

Fixes: 06aa151ad1fc74 ("netfilter: ipt_CLUSTERIP: check MAC address when duplicate config is set")

On Thu, Dec 23, 2021 at 10:48:12AM +0800, Xin Xiong wrote:
> 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.

Applied