5.4-stable review patch. If anyone has any objections, please let me know.
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From: Xiang Mei xmei5@asu.edu
[ Upstream commit 5e28d5a3f774f118896aec17a3a20a9c5c9dfc64 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- 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 c466d255f7865..2a4331a084949 100644 --- a/net/sched/sch_qfq.c +++ b/net/sched/sch_qfq.c @@ -408,7 +408,7 @@ 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;
@@ -444,12 +444,16 @@ 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", @@ -550,10 +554,10 @@ static int qfq_delete_class(struct Qdisc *sch, unsigned long arg)
qdisc_purge_queue(cl->qdisc); qdisc_class_hash_remove(&q->clhash, &cl->common); + qfq_destroy_class(sch, cl);
sch_tree_unlock(sch);
- qfq_destroy_class(sch, cl); return 0; }
@@ -620,6 +624,7 @@ 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; @@ -628,8 +633,13 @@ static int qfq_dump_class(struct Qdisc *sch, unsigned long arg, nest = nla_nest_start_noflag(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);
@@ -646,8 +656,10 @@ 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 ||