bonding: bond_slave_info_query() fix

bond_slave_info_query() should keep a read lock while accessing slave info,
or risk accessing stale data and corruption.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bonding/bond_main.c

@@ -2213,33 +2213,24 @@ static int bond_slave_info_query(struct net_device *bond_dev, struct ifslave *in
 {
 	struct bonding *bond = netdev_priv(bond_dev);
 	struct slave *slave;
-	int i, found = 0;
-
-	if (info->slave_id < 0) {
-		return -ENODEV;
-	}
+	int i, res = -ENODEV;
 
 	read_lock(&bond->lock);
 
 	bond_for_each_slave(bond, slave, i) {
 		if (i == (int)info->slave_id) {
-			found = 1;
-			break;
-		}
-	}
-
-	read_unlock(&bond->lock);
-
-	if (found) {
+			res = 0;
 			strcpy(info->slave_name, slave->dev->name);
 			info->link = slave->link;
 			info->state = slave->state;
 			info->link_failure_count = slave->link_failure_count;
-	} else {
-		return -ENODEV;
+			break;
+		}
 	}
 
-	return 0;
+	read_unlock(&bond->lock);
+
+	return res;
 }
 
 /*-------------------------------- Monitoring -------------------------------*/