netdev - [PATCH] xfrm: fix refcount leak in __xfrm_policy

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Date:   Sun, 24 Jul 2022 17:55:58 +0800
From:   Xin Xiong <xiongx18@...an.edu.cn>
To:     Steffen Klassert <steffen.klassert@...unet.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        “David S . Miller  
        <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        James Morris <jmorris@...ei.org>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     yuanxzhang@...an.edu.cn, Xin Xiong <xiongx18@...an.edu.cn>,
        Xin Tan <tanxin.ctf@...il.com>
Subject: [PATCH] xfrm: fix refcount leak in __xfrm_policy_check()

The issue happens on an error path in __xfrm_policy_check(). When the
fetching process of the object `pols[1]` fails, the function simply
returns 0, forgetting to decrement the reference count of `pols[0]`,
which is incremented earlier by either xfrm_sk_policy_lookup() or
xfrm_policy_lookup(). This may result in memory leaks.

Fix it by decreasing the reference count of `pols[0]` in that path.

Fixes: 134b0fc544ba ("IPsec: propagate security module errors up from flow_cache_lookup")
Signed-off-by: Xin Xiong <xiongx18@...an.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@...il.com>
---
 net/xfrm/xfrm_policy.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index f1a0bab920a5..4f8bbb825abc 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -3599,6 +3599,7 @@ int __xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *skb,
 		if (pols[1]) {
 			if (IS_ERR(pols[1])) {
 				XFRM_INC_STATS(net, LINUX_MIB_XFRMINPOLERROR);
+				xfrm_pol_put(pols[0]);
 				return 0;
 			}
 			pols[1]->curlft.use_time = ktime_get_real_seconds();
-- 
2.25.1