From aeb04858c4906fc5ecc71f6c7aeddd8028120e5f Mon Sep 17 00:00:00 2001 From: Victor Nogueira Date: Fri, 25 Apr 2025 19:07:07 -0300 Subject: [PATCH] net_sched: ets: Fix double list add in class with netem as child qdisc stable inclusion from stable-v6.6.90 commit 72c3da7e6ceb74e74ddbb5a305a35c9fdfcac6e3 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IC9928 CVE: CVE-2025-37914 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=72c3da7e6ceb74e74ddbb5a305a35c9fdfcac6e3 -------------------------------- [ Upstream commit 1a6d0c00fa07972384b0c308c72db091d49988b6 ] As described in Gerrard's report [1], there are use cases where a netem child qdisc will make the parent qdisc's enqueue callback reentrant. In the case of ets, there won't be a UAF, but the code will add the same classifier to the list twice, which will cause memory corruption. In addition to checking for qlen being zero, this patch checks whether the class was already added to the active_list (cl_is_active) before doing the addition to cater for the reentrant case. [1] https://lore.kernel.org/netdev/CAHcdcOm+03OD2j6R0=YHKqmy=VgJ8xEOKuP6c7mSgnp-TEJJbw@mail.gmail.com/ Fixes: 37d9cf1a3ce3 ("sched: Fix detection of empty queues in child qdiscs") Acked-by: Jamal Hadi Salim Signed-off-by: Victor Nogueira Link: https://patch.msgid.link/20250425220710.3964791-4-victor@mojatatu.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin (cherry picked from commit 72c3da7e6ceb74e74ddbb5a305a35c9fdfcac6e3) Signed-off-by: Wentao Guan --- net/sched/sch_ets.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/net/sched/sch_ets.c b/net/sched/sch_ets.c index 3de3d90ef3fd..73c3e2f4cb5f 100644 --- a/net/sched/sch_ets.c +++ b/net/sched/sch_ets.c @@ -74,6 +74,11 @@ static const struct nla_policy ets_class_policy[TCA_ETS_MAX + 1] = { [TCA_ETS_QUANTA_BAND] = { .type = NLA_U32 }, }; +static bool cl_is_active(struct ets_class *cl) +{ + return !list_empty(&cl->alist); +} + static int ets_quantum_parse(struct Qdisc *sch, const struct nlattr *attr, unsigned int *quantum, struct netlink_ext_ack *extack) @@ -416,7 +421,6 @@ static int ets_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct ets_sched *q = qdisc_priv(sch); struct ets_class *cl; int err = 0; - bool first; cl = ets_classify(skb, sch, &err); if (!cl) { @@ -426,7 +430,6 @@ static int ets_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch, return err; } - first = !cl->qdisc->q.qlen; err = qdisc_enqueue(skb, cl->qdisc, to_free); if (unlikely(err != NET_XMIT_SUCCESS)) { if (net_xmit_drop_count(err)) { @@ -436,7 +439,7 @@ static int ets_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch, return err; } - if (first && !ets_class_is_strict(q, cl)) { + if (!cl_is_active(cl) && !ets_class_is_strict(q, cl)) { list_add_tail(&cl->alist, &q->active); cl->deficit = cl->quantum; } -- Gitee