net_sched: introduce tclass_del_notify()
Like for TC actions, ->delete() is a special case,
we have to prepare and fill the notification before delete
otherwise would get use-after-free after we remove the
reference count.
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>
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 330ffae..3ef4eb5 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1618,6 +1618,38 @@
n->nlmsg_flags & NLM_F_ECHO);
}
+static int tclass_del_notify(struct net *net,
+ const struct Qdisc_class_ops *cops,
+ struct sk_buff *oskb, struct nlmsghdr *n,
+ struct Qdisc *q, unsigned long cl)
+{
+ u32 portid = oskb ? NETLINK_CB(oskb).portid : 0;
+ struct sk_buff *skb;
+ int err = 0;
+
+ if (!cops->delete)
+ return -EOPNOTSUPP;
+
+ skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
+ if (!skb)
+ return -ENOBUFS;
+
+ if (tc_fill_tclass(skb, q, cl, portid, n->nlmsg_seq, 0,
+ RTM_DELTCLASS) < 0) {
+ kfree_skb(skb);
+ return -EINVAL;
+ }
+
+ err = cops->delete(q, cl);
+ if (err) {
+ kfree_skb(skb);
+ return err;
+ }
+
+ return rtnetlink_send(skb, net, portid, RTNLGRP_TC,
+ n->nlmsg_flags & NLM_F_ECHO);
+}
+
static int tc_ctl_tclass(struct sk_buff *skb, struct nlmsghdr *n,
struct netlink_ext_ack *extack)
{
@@ -1722,12 +1754,7 @@
goto out;
break;
case RTM_DELTCLASS:
- err = -EOPNOTSUPP;
- if (cops->delete)
- err = cops->delete(q, cl);
- if (err == 0)
- tclass_notify(net, skb, n, q, cl,
- RTM_DELTCLASS);
+ err = tclass_del_notify(net, cops, skb, n, q, cl);
goto out;
case RTM_GETTCLASS:
err = tclass_notify(net, skb, n, q, cl, RTM_NEWTCLASS);