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| author | WANG Cong <xiyou.wangcong@gmail.com> | 2015-10-01 11:37:42 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-10-05 06:30:33 -0700 |
| commit | 6bd00b850635abb0044e06101761533c8beba79c (patch) | |
| tree | 65141acd5f97da77b3b997646ec270b4037ac1bb /net | |
| parent | fec31ffffa6e05845ab13908d0ac0d5a10816836 (diff) | |
| download | linux-6bd00b850635abb0044e06101761533c8beba79c.tar.gz linux-6bd00b850635abb0044e06101761533c8beba79c.tar.bz2 linux-6bd00b850635abb0044e06101761533c8beba79c.zip | |
act_mirred: fix a race condition on mirred_list
After commit 1ce87720d456 ("net: sched: make cls_u32 lockless")
we began to release tc actions in a RCU callback. However,
mirred action relies on RTNL lock to protect the global
mirred_list, therefore we could have a race condition
between RCU callback and netdevice event, which caused
a list corruption as reported by Vinson.
Instead of relying on RTNL lock, introduce a spinlock to
protect this list.
Note, in non-bind case, it is still called with RTNL lock,
therefore should disable BH too.
Reported-by: Vinson Lee <vlee@twopensource.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Cong Wang <cwang@twopensource.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/sched/act_mirred.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c index 2d1be4a760fd..3e7c51a8ca38 100644 --- a/net/sched/act_mirred.c +++ b/net/sched/act_mirred.c @@ -31,13 +31,17 @@ #define MIRRED_TAB_MASK 7 static LIST_HEAD(mirred_list); +static DEFINE_SPINLOCK(mirred_list_lock); static void tcf_mirred_release(struct tc_action *a, int bind) { struct tcf_mirred *m = to_mirred(a); struct net_device *dev = rcu_dereference_protected(m->tcfm_dev, 1); + /* We could be called either in a RCU callback or with RTNL lock held. */ + spin_lock_bh(&mirred_list_lock); list_del(&m->tcfm_list); + spin_unlock_bh(&mirred_list_lock); if (dev) dev_put(dev); } @@ -123,7 +127,9 @@ static int tcf_mirred_init(struct net *net, struct nlattr *nla, } if (ret == ACT_P_CREATED) { + spin_lock_bh(&mirred_list_lock); list_add(&m->tcfm_list, &mirred_list); + spin_unlock_bh(&mirred_list_lock); tcf_hash_insert(a); } @@ -221,7 +227,8 @@ static int mirred_device_event(struct notifier_block *unused, struct tcf_mirred *m; ASSERT_RTNL(); - if (event == NETDEV_UNREGISTER) + if (event == NETDEV_UNREGISTER) { + spin_lock_bh(&mirred_list_lock); list_for_each_entry(m, &mirred_list, tcfm_list) { if (rcu_access_pointer(m->tcfm_dev) == dev) { dev_put(dev); @@ -231,6 +238,8 @@ static int mirred_device_event(struct notifier_block *unused, RCU_INIT_POINTER(m->tcfm_dev, NULL); } } + spin_unlock_bh(&mirred_list_lock); + } return NOTIFY_DONE; } |