This is a note to let you know that I've just added the patch titled
net_sched: reorder pernet ops and act ops registrations
to the 4.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net_sched-reorder-pernet-ops-and-act-ops-registrations.patch
and it can be found in the queue-4.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Thu Nov 10 16:43:03 CET 2016
From: WANG Cong <xiyou.wangcong@xxxxxxxxx>
Date: Tue, 11 Oct 2016 10:56:45 -0700
Subject: net_sched: reorder pernet ops and act ops registrations
From: WANG Cong <xiyou.wangcong@xxxxxxxxx>
[ Upstream commit ab102b80cef28c20b3ef7794806c3a982c6444fc ]
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@xxxxxxxxxxxxxxxxxx>
Tested-by: Krister Johansen <kjlx@xxxxxxxxxxxxxxxxxx>
Cc: Jamal Hadi Salim <jhs@xxxxxxxxxxxx>
Signed-off-by: Cong Wang <xiyou.wangcong@xxxxxxxxx>
Acked-by: Jamal Hadi Salim <jhs@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/sched/act_api.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -341,22 +341,25 @@ int tcf_register_action(struct tc_action
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_acti
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_acti
}
}
write_unlock(&act_mod_lock);
+ if (!err)
+ unregister_pernet_subsys(ops);
return err;
}
EXPORT_SYMBOL(tcf_unregister_action);
Patches currently in stable-queue which might be from xiyou.wangcong@xxxxxxxxx are
queue-4.8/net_sched-reorder-pernet-ops-and-act-ops-registrations.patch
queue-4.8/net-sched-filters-fix-notification-of-filter-delete-with-proper-handle.patch
queue-4.8/ipv4-use-the-right-lock-for-ping_group_range.patch
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html