netdev - [PATCH v3 net 9/9] bridge: Prevent possible race condition in br_fdb_change_mac

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Message-Id: <1391759306-24956-10-git-send-email-makita.toshiaki@lab.ntt.co.jp>
Date:	Fri,  7 Feb 2014 16:48:26 +0900
From:	Toshiaki Makita <makita.toshiaki@....ntt.co.jp>
To:	"David S . Miller" <davem@...emloft.net>,
	Stephen Hemminger <stephen@...workplumber.org>,
	Vlad Yasevich <vyasevic@...hat.com>, netdev@...r.kernel.org
Cc:	Toshiaki Makita <makita.toshiaki@....ntt.co.jp>
Subject: [PATCH v3 net 9/9] bridge: Prevent possible race condition in br_fdb_change_mac_address

br_fdb_change_mac_address() calls fdb_insert()/fdb_delete() without
br->hash_lock.

These hash list updates are racy with br_fdb_update()/br_fdb_cleanup().

Signed-off-by: Toshiaki Makita <makita.toshiaki@....ntt.co.jp>
Acked-by: Vlad Yasevich <vyasevic@...hat.com>
---
 net/bridge/br_fdb.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index 0426dff..9203d5a 100644
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c
@@ -191,6 +191,8 @@ void br_fdb_change_mac_address(struct net_bridge *br, const u8 *newaddr)
 	struct net_port_vlans *pv;
 	u16 vid = 0;
 
+	spin_lock_bh(&br->hash_lock);
+
 	/* If old entry was unassociated with any port, then delete it. */
 	f = __br_fdb_get(br, br->dev->dev_addr, 0);
 	if (f && f->is_local && !f->dst)
@@ -204,7 +206,7 @@ void br_fdb_change_mac_address(struct net_bridge *br, const u8 *newaddr)
 	 */
 	pv = br_get_vlan_info(br);
 	if (!pv)
-		return;
+		goto out;
 
 	for_each_set_bit_from(vid, pv->vlan_bitmap, VLAN_N_VID) {
 		f = __br_fdb_get(br, br->dev->dev_addr, vid);
@@ -212,6 +214,8 @@ void br_fdb_change_mac_address(struct net_bridge *br, const u8 *newaddr)
 			fdb_delete_local(br, NULL, f);
 		fdb_insert(br, NULL, newaddr, vid);
 	}
+out:
+	spin_unlock_bh(&br->hash_lock);
 }
 
 void br_fdb_cleanup(unsigned long _data)
-- 
1.8.1.2

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