netdev - [PATCH net-next] hsr: fix refcnt leak of hsr slave interface

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Message-Id: <20200305000254.8217-1-ap420073@gmail.com>
Date:   Thu,  5 Mar 2020 00:02:54 +0000
From:   Taehee Yoo <ap420073@...il.com>
To:     davem@...emloft.net, kuba@...nel.org, netdev@...r.kernel.org
Cc:     ap420073@...il.com
Subject: [PATCH net-next] hsr: fix refcnt leak of hsr slave interface

In the commit e0a4b99773d3 ("hsr: use upper/lower device infrastructure"),
dev_get() was removed but dev_put() in the error path wasn't removed.
So, if creating hsr interface command is failed, the reference counter leak
of lower interface would occur.

Test commands:
    ip link add dummy0 type dummy
    ip link add ipvlan0 link dummy0 type ipvlan mode l2
    ip link add ipvlan1 link dummy0 type ipvlan mode l2
    ip link add hsr0 type hsr slave1 ipvlan0 slave2 ipvlan1
    ip link del ipvlan0

Result:
[  633.271992][ T1280] unregister_netdevice: waiting for ipvlan0 to become free. Usage count = -1

Fixes: e0a4b99773d3 ("hsr: use upper/lower device infrastructure")
Signed-off-by: Taehee Yoo <ap420073@...il.com>
---

The commit e0a4b99773d3 ("hsr: use upper/lower device infrastructure")
is not merged into "net" yet.
So, the target branch is "net-next".

 net/hsr/hsr_slave.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/net/hsr/hsr_slave.c b/net/hsr/hsr_slave.c
index 123605cb5420..d3547e8c6d5b 100644
--- a/net/hsr/hsr_slave.c
+++ b/net/hsr/hsr_slave.c
@@ -108,7 +108,7 @@ static int hsr_portdev_setup(struct hsr_priv *hsr, struct net_device *dev,
 
 	res = dev_set_promiscuity(dev, 1);
 	if (res)
-		goto fail_promiscuity;
+		return res;
 
 	master = hsr_port_get_hsr(hsr, HSR_PT_MASTER);
 	hsr_dev = master->dev;
@@ -128,9 +128,6 @@ static int hsr_portdev_setup(struct hsr_priv *hsr, struct net_device *dev,
 	netdev_upper_dev_unlink(dev, hsr_dev);
 fail_upper_dev_link:
 	dev_set_promiscuity(dev, -1);
-fail_promiscuity:
-	dev_put(dev);
-
 	return res;
 }
 
-- 
2.17.1