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net: bridge: Fix locking in br_fdb_find_port()

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Callers of br_fdb_find() need to hold the hash lock, which
br_fdb_find_port() doesn't do. However, since br_fdb_find_port() is not
doing any actual FDB manipulation, the hash lock is not really needed at
all. So convert to br_fdb_find_rcu(), surrounded by rcu_read_lock() /
_unlock() pair.

The device pointer copied from inside the FDB entry is then kept alive
by the RTNL lock, which br_fdb_find_port() asserts.

Fixes: 4d4fd36126 ("net: bridge: Publish bridge accessor functions")
Signed-off-by: Petr Machata <petrm@mellanox.com>
Acked-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Petr Machata 2018-06-08 15:11:47 +02:00 committed by David S. Miller
parent 6c206b2009
commit 873aca2ee8
1 changed files with 3 additions and 1 deletions
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4
net/bridge/br_fdb.c
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@ -135,9 +135,11 @@ struct net_device *br_fdb_find_port(const struct net_device *br_dev,
return NULL;
br = netdev_priv(br_dev);
f = br_fdb_find(br, addr, vid);
rcu_read_lock();
f = br_fdb_find_rcu(br, addr, vid);
if (f && f->dst)
dev = f->dst->dev;
rcu_read_unlock();
return dev;
}