[PATCH 4.1 142/159] bridge: netlink: fix slave_changelink/br_setport race conditions

Greg Kroah-Hartman
2015-09-26T21:19:14Z

From: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>

[ Upstream commit 963ad94853000ab100f5ff19eea80095660d41b4 ]

Since slave_changelink support was added there have been a few race
conditions when using br_setport() since some of the port functions it
uses require the bridge lock. It is very easy to trigger a lockup due to
some internal spin_lock() usage without bh disabled, also it's possible to
get the bridge into an inconsistent state.

Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Fixes: 3ac636b8591c ("bridge: implement rtnl_link_ops->slave_changelink")
Reviewed-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/bridge/br_netlink.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -711,9 +711,17 @@ static int br_port_slave_changelink(stru
struct nlattr *tb[],
struct nlattr *data[])
{
+ struct net_bridge *br = netdev_priv(brdev);
+ int ret;
+
if (!data)
return 0;
- return br_setport(br_port_get_rtnl(dev), data);
+
+ spin_lock_bh(&br->lock);
+ ret = br_setport(br_port_get_rtnl(dev), data);
+ spin_unlock_bh(&br->lock);
+
+ return ret;
}

static int br_port_fill_slave_info(struct sk_buff *skb,