From: Xiang Mei <xmei5@asu.edu> mainline inclusion from mainline-v6.16-rc5 commit 5e28d5a3f774f118896aec17a3a20a9c5c9dfc64 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/ICPD9I CVE: CVE-2025-38477 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- A race condition can occur when 'agg' is modified in qfq_change_agg (called during qfq_enqueue) while other threads access it concurrently. For example, qfq_dump_class may trigger a NULL dereference, and qfq_delete_class may cause a use-after-free. This patch addresses the issue by: 1. Moved qfq_destroy_class into the critical section. 2. Added sch_tree_lock protection to qfq_dump_class and qfq_dump_class_stats. Fixes: 462dbc9101ac ("pkt_sched: QFQ Plus: fair-queueing service at DRR cost") Signed-off-by: Xiang Mei <xmei5@asu.edu> Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> Conflicts: net/sched/sch_qfq.c [commit c69a9b023f65 and 29cbcd858283 are not backport] Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com> --- net/sched/sch_qfq.c | 30 +++++++++++++++++++++--------- 1 file changed, 21 insertions(+), 9 deletions(-) diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c index 510d012813ce..ae03a75c7249 100644 --- a/net/sched/sch_qfq.c +++ b/net/sched/sch_qfq.c @@ -416,7 +416,7 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, bool existing = false; struct nlattr *tb[TCA_QFQ_MAX + 1]; struct qfq_aggregate *new_agg = NULL; - u32 weight, lmax, inv_w; + u32 weight, lmax, inv_w, old_weight, old_lmax; int err; int delta_w; @@ -452,12 +452,16 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, inv_w = ONE_FP / weight; weight = ONE_FP / inv_w; - if (cl != NULL && - lmax == cl->agg->lmax && - weight == cl->agg->class_weight) - return 0; /* nothing to change */ + if (cl != NULL) { + sch_tree_lock(sch); + old_weight = cl->agg->class_weight; + old_lmax = cl->agg->lmax; + sch_tree_unlock(sch); + if (lmax == old_lmax && weight == old_weight) + return 0; /* nothing to change */ + } - delta_w = weight - (cl ? cl->agg->class_weight : 0); + delta_w = weight - (cl ? old_weight : 0); if (q->wsum + delta_w > QFQ_MAX_WSUM) { pr_notice("qfq: total weight out of range (%d + %u)\n", @@ -559,10 +563,10 @@ static int qfq_delete_class(struct Qdisc *sch, unsigned long arg) qfq_purge_queue(cl); qdisc_class_hash_remove(&q->clhash, &cl->common); + qfq_destroy_class(sch, cl); sch_tree_unlock(sch); - qfq_destroy_class(sch, cl); return 0; } @@ -629,6 +633,7 @@ static int qfq_dump_class(struct Qdisc *sch, unsigned long arg, { struct qfq_class *cl = (struct qfq_class *)arg; struct nlattr *nest; + u32 class_weight, lmax; tcm->tcm_parent = TC_H_ROOT; tcm->tcm_handle = cl->common.classid; @@ -637,8 +642,13 @@ static int qfq_dump_class(struct Qdisc *sch, unsigned long arg, nest = nla_nest_start(skb, TCA_OPTIONS); if (nest == NULL) goto nla_put_failure; - if (nla_put_u32(skb, TCA_QFQ_WEIGHT, cl->agg->class_weight) || - nla_put_u32(skb, TCA_QFQ_LMAX, cl->agg->lmax)) + + sch_tree_lock(sch); + class_weight = cl->agg->class_weight; + lmax = cl->agg->lmax; + sch_tree_unlock(sch); + if (nla_put_u32(skb, TCA_QFQ_WEIGHT, class_weight) || + nla_put_u32(skb, TCA_QFQ_LMAX, lmax)) goto nla_put_failure; return nla_nest_end(skb, nest); @@ -655,8 +665,10 @@ static int qfq_dump_class_stats(struct Qdisc *sch, unsigned long arg, memset(&xstats, 0, sizeof(xstats)); + sch_tree_lock(sch); xstats.weight = cl->agg->class_weight; xstats.lmax = cl->agg->lmax; + sch_tree_unlock(sch); if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch), d, NULL, &cl->bstats) < 0 || -- 2.25.1