From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Wed, 5 Feb 2020 14:53:30 +0300
Subject: net: sched: prevent a use after free
Patch-mainline: v5.6-rc1
Git-commit: 7a02ea65027523386ab4ba4af0ab93497b3073df
References: jsc#SLE-15172
The bug is that we call kfree_skb(skb) and then pass "skb" to
qdisc_pkt_len(skb) on the next line, which is a use after free.
Also Cong Wang points out that it's better to delay the actual
frees until we drop the rtnl lock so we should use rtnl_kfree_skbs()
instead of kfree_skb().
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Fixes: ec97ecf1ebe4 ("net: sched: add Flow Queue PIE packet scheduler")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
net/sched/sch_fq_pie.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/sched/sch_fq_pie.c
+++ b/net/sched/sch_fq_pie.c
@@ -349,9 +349,9 @@ static int fq_pie_change(struct Qdisc *s
while (sch->q.qlen > sch->limit) {
struct sk_buff *skb = fq_pie_qdisc_dequeue(sch);
- kfree_skb(skb);
len_dropped += qdisc_pkt_len(skb);
num_dropped += 1;
+ rtnl_kfree_skbs(skb, skb);
}
qdisc_tree_reduce_backlog(sch, num_dropped, len_dropped);