From 63d935a736ac53050624bf9ecb44d06eb7869a72 Mon Sep 17 00:00:00 2001 From: Cong Wang Date: Fri, 4 Apr 2025 05:16:31 +0800 Subject: [PATCH] codel: remove sch->q.qlen check before qdisc_tree_reduce_backlog() ANBZ: #21289 commit cc71a757da78dd4aa1b4a9b19cb011833730ccf2 stable. commit 342debc12183b51773b3345ba267e9263bdfaaef upstream. After making all ->qlen_notify() callbacks idempotent, now it is safe to remove the check of qlen!=0 from both fq_codel_dequeue() and codel_qdisc_dequeue(). Reported-by: Gerrard Tai Fixes: 4b549a2ef4be ("fq_codel: Fair Queue Codel AQM") Fixes: 76e3cc126bb2 ("codel: Controlled Delay AQM") Signed-off-by: Cong Wang Reviewed-by: Simon Horman Link: https://patch.msgid.link/20250403211636.166257-1-xiyou.wangcong@gmail.com Acked-by: Jamal Hadi Salim Signed-off-by: Paolo Abeni Signed-off-by: Siddh Raman Pant Signed-off-by: Greg Kroah-Hartman Fixes: CVE-2025-37798 Signed-off-by: Xiao Long Signed-off-by: Shiloong --- net/sched/sch_codel.c | 5 +---- net/sched/sch_fq_codel.c | 6 ++---- 2 files changed, 3 insertions(+), 8 deletions(-) diff --git a/net/sched/sch_codel.c b/net/sched/sch_codel.c index 30169b3adbbb..d9eff03deada 100644 --- a/net/sched/sch_codel.c +++ b/net/sched/sch_codel.c @@ -95,10 +95,7 @@ static struct sk_buff *codel_qdisc_dequeue(struct Qdisc *sch) &q->stats, qdisc_pkt_len, codel_get_enqueue_time, drop_func, dequeue_func); - /* We cant call qdisc_tree_reduce_backlog() if our qlen is 0, - * or HTB crashes. Defer it for next round. - */ - if (q->stats.drop_count && sch->q.qlen) { + if (q->stats.drop_count) { qdisc_tree_reduce_backlog(sch, q->stats.drop_count, q->stats.drop_len); q->stats.drop_count = 0; q->stats.drop_len = 0; diff --git a/net/sched/sch_fq_codel.c b/net/sched/sch_fq_codel.c index 99e8db262198..87867b4e8aca 100644 --- a/net/sched/sch_fq_codel.c +++ b/net/sched/sch_fq_codel.c @@ -314,10 +314,8 @@ static struct sk_buff *fq_codel_dequeue(struct Qdisc *sch) } qdisc_bstats_update(sch, skb); flow->deficit -= qdisc_pkt_len(skb); - /* We cant call qdisc_tree_reduce_backlog() if our qlen is 0, - * or HTB crashes. Defer it for next round. - */ - if (q->cstats.drop_count && sch->q.qlen) { + + if (q->cstats.drop_count) { qdisc_tree_reduce_backlog(sch, q->cstats.drop_count, q->cstats.drop_len); q->cstats.drop_count = 0; -- Gitee