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@lab.ntt.co.jp>
Acked-by: Vlad Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 1 deletions

diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index 0426dff4b3fd..9203d5a1943f 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)