diff options
| author | Victor Nogueira <victor@mojatatu.com> | 2025-04-25 19:07:08 -0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2025-04-28 15:55:07 -0700 |
| commit | f139f37dcdf34b67f5bf92bc8e0f7f6b3ac63aa4 (patch) | |
| tree | 43a96967e799efae5e65baf7ad8a6e059c5ca1b5 /net | |
| parent | 1a6d0c00fa07972384b0c308c72db091d49988b6 (diff) | |
net_sched: qfq: Fix double list add in class with netem as child qdisc
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 qfq, there won't be a UAF, but the code will add the same
classifier to the list twice, which will cause memory corruption.
This patch checks whether the class was already added to the agg->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 <jhs@mojatatu.com>
Signed-off-by: Victor Nogueira <victor@mojatatu.com>
Link: https://patch.msgid.link/20250425220710.3964791-5-victor@mojatatu.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/sched/sch_qfq.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c index 687a932eb9b2..bf1282cb22eb 100644 --- a/net/sched/sch_qfq.c +++ b/net/sched/sch_qfq.c @@ -202,6 +202,11 @@ struct qfq_sched { */ enum update_reason {enqueue, requeue}; +static bool cl_is_active(struct qfq_class *cl) +{ + return !list_empty(&cl->alist); +} + static struct qfq_class *qfq_find_class(struct Qdisc *sch, u32 classid) { struct qfq_sched *q = qdisc_priv(sch); @@ -1215,7 +1220,6 @@ static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct qfq_class *cl; struct qfq_aggregate *agg; int err = 0; - bool first; cl = qfq_classify(skb, sch, &err); if (cl == NULL) { @@ -1237,7 +1241,6 @@ static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch, } gso_segs = skb_is_gso(skb) ? skb_shinfo(skb)->gso_segs : 1; - first = !cl->qdisc->q.qlen; err = qdisc_enqueue(skb, cl->qdisc, to_free); if (unlikely(err != NET_XMIT_SUCCESS)) { pr_debug("qfq_enqueue: enqueue failed %d\n", err); @@ -1253,8 +1256,8 @@ static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch, ++sch->q.qlen; agg = cl->agg; - /* if the queue was not empty, then done here */ - if (!first) { + /* if the class is active, then done here */ + if (cl_is_active(cl)) { if (unlikely(skb == cl->qdisc->ops->peek(cl->qdisc)) && list_first_entry(&agg->active, struct qfq_class, alist) == cl && cl->deficit < len) |