netdev - [PATCH net] team: fix possible recursive locking when add slaves

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Message-Id: <20190417121211.21063-1-liuhangbin@gmail.com>
Date:   Wed, 17 Apr 2019 20:12:11 +0800
From:   Hangbin Liu <liuhangbin@...il.com>
To:     netdev@...r.kernel.org
Cc:     Jiri Pirko <jiri@...nulli.us>, davem@...emloft.net,
        Xin Long <lucien.xin@...il.com>,
        Hangbin Liu <liuhangbin@...il.com>
Subject: [PATCH net] team: fix possible recursive locking when add slaves

If we add a bond device which is already the master of the team interface,
we will hold the team->lock in team_add_slave() first and then request the
lock in team_set_mac_address() again. The functions are called like:

- team_add_slave()
 - team_port_add()
   - team_port_enter()
     - team_modeop_port_enter()
       - __set_port_dev_addr()
         - dev_set_mac_address()
           - bond_set_mac_address()
             - dev_set_mac_address()
  	       - team_set_mac_address

Although team_upper_dev_link() would check the upper devices but it is
called too late. Fix it by adding a checking before processing the slave.

Fixes: 3d249d4ca7d0 ("net: introduce ethernet teaming device")
Signed-off-by: Hangbin Liu <liuhangbin@...il.com>
---
 drivers/net/team/team.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/team/team.c b/drivers/net/team/team.c
index 9ce61b019aad..8313c4f2b635 100644
--- a/drivers/net/team/team.c
+++ b/drivers/net/team/team.c
@@ -1156,6 +1156,13 @@ static int team_port_add(struct team *team, struct net_device *port_dev,
 		return -EINVAL;
 	}
 
+	if (netdev_has_upper_dev(dev, port_dev)) {
+		NL_SET_ERR_MSG(extack, "Device is already an upper device of the team interface");
+		netdev_err(dev, "Device %s is already an upper device "
+				"of the team interface\n", portname);
+		return -EBUSY;
+	}
+
 	if (port_dev->features & NETIF_F_VLAN_CHALLENGED &&
 	    vlan_uses_dev(dev)) {
 		NL_SET_ERR_MSG(extack, "Device is VLAN challenged and team device has VLAN set up");
-- 
2.19.2