diff options
| author | WANG Cong | 2016-10-11 10:56:45 -0700 |
|---|---|---|
| committer | David S. Miller | 2016-10-13 10:26:43 -0400 |
| commit | ab102b80cef28c20b3ef7794806c3a982c6444fc (patch) | |
| tree | f1f4ef200fb7180cccc07d88978c1d4ff42aae92 /net/sched | |
| parent | d1ef006dc116bf6487426b0b50c1bf2bf51e6423 (diff) | |
net_sched: reorder pernet ops and act ops registrations
Krister reported a kernel NULL pointer dereference after
tcf_action_init_1() invokes a_o->init(), it is a race condition
where one thread calling tcf_register_action() to initialize
the netns data after putting act ops in the global list and
the other thread searching the list and then calling
a_o->init(net, ...).
Fix this by moving the pernet ops registration before making
the action ops visible. This is fine because: a) we don't
rely on act_base in pernet ops->init(), b) in the worst case we
have a fully initialized netns but ops is still not ready so
new actions still can't be created.
Reported-by: Krister Johansen <kjlx@templeofstupid.com>
Tested-by: Krister Johansen <kjlx@templeofstupid.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.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/sched')
| -rw-r--r-- | net/sched/act_api.c | 19 |
1 files changed, 11 insertions, 8 deletions
diff --git a/net/sched/act_api.c b/net/sched/act_api.c index c9102172ce3b..a512b18c0088 100644 --- a/net/sched/act_api.c +++ b/net/sched/act_api.c @@ -341,22 +341,25 @@ int tcf_register_action(struct tc_action_ops *act, if (!act->act || !act->dump || !act->init || !act->walk || !act->lookup) return -EINVAL; + /* We have to register pernet ops before making the action ops visible, + * otherwise tcf_action_init_1() could get a partially initialized + * netns. + */ + ret = register_pernet_subsys(ops); + if (ret) + return ret; + write_lock(&act_mod_lock); list_for_each_entry(a, &act_base, head) { if (act->type == a->type || (strcmp(act->kind, a->kind) == 0)) { write_unlock(&act_mod_lock); + unregister_pernet_subsys(ops); return -EEXIST; } } list_add_tail(&act->head, &act_base); write_unlock(&act_mod_lock); - ret = register_pernet_subsys(ops); - if (ret) { - tcf_unregister_action(act, ops); - return ret; - } - return 0; } EXPORT_SYMBOL(tcf_register_action); @@ -367,8 +370,6 @@ int tcf_unregister_action(struct tc_action_ops *act, struct tc_action_ops *a; int err = -ENOENT; - unregister_pernet_subsys(ops); - write_lock(&act_mod_lock); list_for_each_entry(a, &act_base, head) { if (a == act) { @@ -378,6 +379,8 @@ int tcf_unregister_action(struct tc_action_ops *act, } } write_unlock(&act_mod_lock); + if (!err) + unregister_pernet_subsys(ops); return err; } EXPORT_SYMBOL(tcf_unregister_action); |