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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Ido Schimmel <idosch@mellanox.com>,
        Nikolay Aleksandrov <nikolay@cumulusnetworks.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.15 068/122] bridge: Fix VLAN reference count problem
Date:   Wed,  7 Mar 2018 11:38:00 -0800
Message-Id: <20180307191739.211643933@linuxfoundation.org>
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4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ido Schimmel <idosch@mellanox.com>


[ Upstream commit 0e5a82efda872c2469c210957d7d4161ef8f4391 ]

When a VLAN is added on a port, a reference is taken on the
corresponding master VLAN entry. If it does not already exist, then it
is created and a reference taken.

However, in the second case a reference is not really taken when
CONFIG_REFCOUNT_FULL is enabled as refcount_inc() is replaced by
refcount_inc_not_zero().

Fix this by using refcount_set() on a newly created master VLAN entry.

Fixes: 251277598596 ("net, bridge: convert net_bridge_vlan.refcnt from atomic_t to refcount_t")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Acked-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/bridge/br_vlan.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/net/bridge/br_vlan.c
+++ b/net/bridge/br_vlan.c
@@ -168,6 +168,8 @@ static struct net_bridge_vlan *br_vlan_g
 		masterv = br_vlan_find(vg, vid);
 		if (WARN_ON(!masterv))
 			return NULL;
+		refcount_set(&masterv->refcnt, 1);
+		return masterv;
 	}
 	refcount_inc(&masterv->refcnt);