netdev - [Patch net] 8021q: fix a memory leak for VLAN 0 device

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Date:   Tue,  9 Jan 2018 13:40:41 -0800
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     netdev@...r.kernel.org
Cc:     dvyukov@...gle.com, Cong Wang <xiyou.wangcong@...il.com>,
        Vlad Yasevich <vyasevich@...il.com>,
        Ben Hutchings <ben.hutchings@...ethink.co.uk>
Subject: [Patch net] 8021q: fix a memory leak for VLAN 0 device

A vlan device with vid 0 is allow to creat by not able to be fully
cleaned up by unregister_vlan_dev() which checks for vlan_id!=0.

Also, VLAN 0 is probably not a valid number and it is kinda
"reserved" for HW accelerating devices, but it is probably too
late to reject it from creation even if makes sense. Instead,
just remove the check in unregister_vlan_dev().

Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
Fixes: ad1afb003939 ("vlan_dev: VLAN 0 should be treated as "no vlan tag" (802.1p packet)")
Cc: Vlad Yasevich <vyasevich@...il.com>
Cc: Ben Hutchings <ben.hutchings@...ethink.co.uk>
Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>
---
 net/8021q/vlan.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c
index 8dfdd94e430f..bad01b14a4ad 100644
--- a/net/8021q/vlan.c
+++ b/net/8021q/vlan.c
@@ -111,12 +111,7 @@ void unregister_vlan_dev(struct net_device *dev, struct list_head *head)
 		vlan_gvrp_uninit_applicant(real_dev);
 	}
 
-	/* Take it out of our own structures, but be sure to interlock with
-	 * HW accelerating devices or SW vlan input packet processing if
-	 * VLAN is not 0 (leave it there for 802.1p).
-	 */
-	if (vlan_id)
-		vlan_vid_del(real_dev, vlan->vlan_proto, vlan_id);
+	vlan_vid_del(real_dev, vlan->vlan_proto, vlan_id);
 
 	/* Get rid of the vlan's reference to real_dev */
 	dev_put(real_dev);
-- 
2.13.0