[net PATCH v3 3/3] net: netprio: fix cgrp create and write priomap race
From: John Fastabend <hidden>
Date: 2012-08-14 22:50:35
Also in:
lkml
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
A race exists where creating cgroups and also updating the priomap may result in losing a priomap update. This is because priomap writers are not protected by rtnl_lock. Move priority writer into rtnl_lock()/rtnl_unlock(). CC: Neil Horman <nhorman@tuxdriver.com> Reported-by: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: John Fastabend <redacted> --- net/core/netprio_cgroup.c | 8 +++----- 1 files changed, 3 insertions(+), 5 deletions(-)
diff --git a/net/core/netprio_cgroup.c b/net/core/netprio_cgroup.c
index f65dba3..c75e3f9 100644
--- a/net/core/netprio_cgroup.c
+++ b/net/core/netprio_cgroup.c@@ -101,12 +101,10 @@ static int write_update_netdev_table(struct net_device *dev) u32 max_len; struct netprio_map *map; - rtnl_lock(); max_len = atomic_read(&max_prioidx) + 1; map = rtnl_dereference(dev->priomap); if (!map || map->priomap_len < max_len) ret = extend_netdev_table(dev, max_len); - rtnl_unlock(); return ret; }
@@ -256,17 +254,17 @@ static int write_priomap(struct cgroup *cgrp, struct cftype *cft, if (!dev) goto out_free_devname; + rtnl_lock(); ret = write_update_netdev_table(dev); if (ret < 0) goto out_put_dev; - rcu_read_lock(); - map = rcu_dereference(dev->priomap); + map = rtnl_dereference(dev->priomap); if (map) map->priomap[prioidx] = priority; - rcu_read_unlock(); out_put_dev: + rtnl_unlock(); dev_put(dev); out_free_devname: