netdev - [PATCH] atm: fix atm_dev refcnt leaks in atmtcp_remove

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Date:   Wed, 29 Jul 2020 21:06:59 +0800
From:   Xin Xiong <xiongx18@...an.edu.cn>
To:     Chas Williams <3chas3@...il.com>,
        linux-atm-general@...ts.sourceforge.net, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Xin Xiong <xiongx18@...an.edu.cn>,
        Xiyu Yang <xiyuyang19@...an.edu.cn>,
        Xin Tan <tanxin.ctf@...il.com>, yuanxzhang@...an.edu.cn
Subject: [PATCH] atm: fix atm_dev refcnt leaks in atmtcp_remove_persistent

atmtcp_remove_persistent() invokes atm_dev_lookup(), which returns a
reference of atm_dev with increased refcount or NULL if fails.

The refcount leaks issues occur in two error handling paths. If
dev_data->persist is zero or PRIV(dev)->vcc isn't NULL, the function
returns 0 without decreasing the refcount kept by a local variable,
resulting in refcount leaks.

Fix the issue by adding atm_dev_put() before returning 0 both when
dev_data->persist is zero or PRIV(dev)->vcc isn't NULL.

Signed-off-by: Xin Xiong <xiongx18@...an.edu.cn>
Signed-off-by: Xiyu Yang <xiyuyang19@...an.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@...il.com>
---
 drivers/atm/atmtcp.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/atm/atmtcp.c b/drivers/atm/atmtcp.c
index d9fd70280482..7f814da3c2d0 100644
--- a/drivers/atm/atmtcp.c
+++ b/drivers/atm/atmtcp.c
@@ -433,9 +433,15 @@ static int atmtcp_remove_persistent(int itf)
 		return -EMEDIUMTYPE;
 	}
 	dev_data = PRIV(dev);
-	if (!dev_data->persist) return 0;
+	if (!dev_data->persist) {
+		atm_dev_put(dev);
+		return 0;
+	}
 	dev_data->persist = 0;
-	if (PRIV(dev)->vcc) return 0;
+	if (PRIV(dev)->vcc) {
+		atm_dev_put(dev);
+		return 0;
+	}
 	kfree(dev_data);
 	atm_dev_put(dev);
 	atm_dev_deregister(dev);
-- 
2.25.1