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@xxxxxxxxx>
Fixes: ec97ecf1ebe4 ("net: sched: add Flow Queue PIE packet scheduler")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
---
v2: Use rtnl_kfree_skbs() instead of kfree_skb(). From static analysis.
Not tested, but I have audited the code pretty close and I think
switing to rtnl_kfree_skbs() is harmless.
net/sched/sch_fq_pie.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/sched/sch_fq_pie.c b/net/sched/sch_fq_pie.c
index bbd0dea6b6b9..214657eb3dfd 100644
--- 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 *sch, struct nlattr *opt,
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);
--
2.11.0
