[PATCH] atm: fix atm_dev refcnt leaks in atmtcp_remove_persistent

[Xin Xiong]

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@xxxxxxxxxxxx>
Signed-off-by: Xiyu Yang <xiyuyang19@xxxxxxxxxxxx>
Signed-off-by: Xin Tan <tanxin.ctf@xxxxxxxxx>
---
 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