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Date: Tue, 3 Mar 2015 14:49:16 +0100
From: Johannes Berg <johannes@...solutions.net>
To: netdev@...r.kernel.org
Cc: Roopa Prabhu <roopa@...ulusnetworks.com>,
Stephen Hemminger <stephen@...workplumber.org>,
Johannes Berg <johannes.berg@...el.com>
Subject: [PATCH v3] bridge: fix bridge netlink RCU usage
From: Johannes Berg <johannes.berg@...el.com>
When the STP timer fires, it can call br_ifinfo_notify(),
which in turn ends up in the new br_get_link_af_size().
This function is annotated to be using RTNL locking, which
clearly isn't the case here, and thus lockdep warns:
===============================
[ INFO: suspicious RCU usage. ]
3.19.0+ #569 Not tainted
-------------------------------
net/bridge/br_private.h:204 suspicious rcu_dereference_protected() usage!
Fix this by doing RCU locking here.
Fixes: b7853d73e39b ("bridge: add vlan info to bridge setlink and dellink notification messages")
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
---
net/bridge/br_netlink.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)
diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 17e0177467f5..72d8efa9b1eb 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -25,19 +25,20 @@
static size_t br_get_link_af_size(const struct net_device *dev)
{
struct net_port_vlans *pv;
+ unsigned int num_vlans;
+ rcu_read_lock();
if (br_port_exists(dev))
- pv = nbp_get_vlan_info(br_port_get_rtnl(dev));
+ pv = nbp_get_vlan_info(br_port_get_rcu(dev));
else if (dev->priv_flags & IFF_EBRIDGE)
- pv = br_get_vlan_info((struct net_bridge *)netdev_priv(dev));
+ pv = br_get_vlan_info(netdev_priv(dev));
else
- return 0;
-
- if (!pv)
- return 0;
+ pv = NULL;
+ num_vlans = pv ? pv->num_vlans : 0;
+ rcu_read_unlock();
/* Each VLAN is returned in bridge_vlan_info along with flags */
- return pv->num_vlans * nla_total_size(sizeof(struct bridge_vlan_info));
+ return num_vlans * nla_total_size(sizeof(struct bridge_vlan_info));
}
static inline size_t br_port_info_size(void)
--
2.1.4
--
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