From: Cong Wang <xiyou.wangcong@gmail.com> stable inclusion from stable-v6.6.90 commit 077e355dae44c77c46b3297c2f158b526384c022 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IC5D94 CVE: CVE-2025-37798 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit df008598b3a00be02a8051fde89ca0fbc416bd55 upstream. drr_qlen_notify() always deletes the DRR class from its active list with list_del(), therefore, it is not idempotent and not friendly to its callers, like fq_codel_dequeue(). Let's make it idempotent to ease qdisc_tree_reduce_backlog() callers' life. Also change other list_del()'s to list_del_init() just to be extra safe. Reported-by: Gerrard Tai <gerrard.tai@starlabs.sg> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Reviewed-by: Simon Horman <horms@kernel.org> Link: https://patch.msgid.link/20250403211033.166059-3-xiyou.wangcong@gmail.com Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com> --- net/sched/sch_drr.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/net/sched/sch_drr.c b/net/sched/sch_drr.c index 19901e77cd3b..f1abd9f84d0d 100644 --- a/net/sched/sch_drr.c +++ b/net/sched/sch_drr.c @@ -105,6 +105,7 @@ static int drr_change_class(struct Qdisc *sch, u32 classid, u32 parentid, return -ENOBUFS; gnet_stats_basic_sync_init(&cl->bstats); + INIT_LIST_HEAD(&cl->alist); cl->common.classid = classid; cl->quantum = quantum; cl->qdisc = qdisc_create_dflt(sch->dev_queue, @@ -229,7 +230,7 @@ static void drr_qlen_notify(struct Qdisc *csh, unsigned long arg) { struct drr_class *cl = (struct drr_class *)arg; - list_del(&cl->alist); + list_del_init(&cl->alist); } static int drr_dump_class(struct Qdisc *sch, unsigned long arg, @@ -390,7 +391,7 @@ static struct sk_buff *drr_dequeue(struct Qdisc *sch) if (unlikely(skb == NULL)) goto out; if (cl->qdisc->q.qlen == 0) - list_del(&cl->alist); + list_del_init(&cl->alist); bstats_update(&cl->bstats, skb); qdisc_bstats_update(sch, skb); @@ -431,7 +432,7 @@ static void drr_reset_qdisc(struct Qdisc *sch) for (i = 0; i < q->clhash.hashsize; i++) { hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) { if (cl->qdisc->q.qlen) - list_del(&cl->alist); + list_del_init(&cl->alist); qdisc_reset(cl->qdisc); } } -- 2.25.1