From f6bab199315b70fd83fe3ee0947bc84c7a35f3d4 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= Date: Wed, 9 Jan 2019 17:09:42 +0100 Subject: sched: Avoid dereferencing skb pointer after child enqueue MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Parent qdiscs may dereference the pointer to the enqueued skb after enqueue. However, both CAKE and TBF call consume_skb() on the original skb when splitting GSO packets, leading to a potential use-after-free in the parent. Fix this by avoiding dereferencing the skb pointer after enqueueing to the child. Signed-off-by: Toke Høiland-Jørgensen Signed-off-by: David S. Miller --- net/sched/sch_qfq.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) (limited to 'net/sched/sch_qfq.c') diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c index dc37c4ead439..8d5e55d5bed2 100644 --- a/net/sched/sch_qfq.c +++ b/net/sched/sch_qfq.c @@ -1210,6 +1210,7 @@ static struct qfq_aggregate *qfq_choose_next_agg(struct qfq_sched *q) static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free) { + unsigned int len = qdisc_pkt_len(skb), gso_segs; struct qfq_sched *q = qdisc_priv(sch); struct qfq_class *cl; struct qfq_aggregate *agg; @@ -1224,17 +1225,17 @@ static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch, } pr_debug("qfq_enqueue: cl = %x\n", cl->common.classid); - if (unlikely(cl->agg->lmax < qdisc_pkt_len(skb))) { + if (unlikely(cl->agg->lmax < len)) { pr_debug("qfq: increasing maxpkt from %u to %u for class %u", - cl->agg->lmax, qdisc_pkt_len(skb), cl->common.classid); - err = qfq_change_agg(sch, cl, cl->agg->class_weight, - qdisc_pkt_len(skb)); + cl->agg->lmax, len, cl->common.classid); + err = qfq_change_agg(sch, cl, cl->agg->class_weight, len); if (err) { cl->qstats.drops++; return qdisc_drop(skb, sch, to_free); } } + gso_segs = skb_is_gso(skb) ? skb_shinfo(skb)->gso_segs : 1; err = qdisc_enqueue(skb, cl->qdisc, to_free); if (unlikely(err != NET_XMIT_SUCCESS)) { pr_debug("qfq_enqueue: enqueue failed %d\n", err); @@ -1245,8 +1246,9 @@ static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch, return err; } - bstats_update(&cl->bstats, skb); - qdisc_qstats_backlog_inc(sch, skb); + cl->bstats.bytes += len; + cl->bstats.packets += gso_segs; + sch->qstats.backlog += len; ++sch->q.qlen; agg = cl->agg; @@ -1254,7 +1256,7 @@ static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch, if (cl->qdisc->q.qlen != 1) { if (unlikely(skb == cl->qdisc->ops->peek(cl->qdisc)) && list_first_entry(&agg->active, struct qfq_class, alist) - == cl && cl->deficit < qdisc_pkt_len(skb)) + == cl && cl->deficit < len) list_move_tail(&cl->alist, &agg->active); return err; -- cgit v1.2.3 From 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= Date: Wed, 9 Jan 2019 17:09:43 +0100 Subject: sched: Fix detection of empty queues in child qdiscs MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Several qdiscs check on enqueue whether the packet was enqueued to a class with an empty queue, in which case the class is activated. This is done by checking if the qlen is exactly 1 after enqueue. However, if GSO splitting is enabled in the child qdisc, a single packet can result in a qlen longer than 1. This means the activation check fails, leading to a stalled queue. Fix this by checking if the queue is empty *before* enqueue, and running the activation logic if this was the case. Reported-by: Pete Heist Signed-off-by: Toke Høiland-Jørgensen Signed-off-by: David S. Miller --- net/sched/sch_qfq.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'net/sched/sch_qfq.c') diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c index 8d5e55d5bed2..29f5c4a24688 100644 --- a/net/sched/sch_qfq.c +++ b/net/sched/sch_qfq.c @@ -1215,6 +1215,7 @@ 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) { @@ -1236,6 +1237,7 @@ 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); @@ -1253,7 +1255,7 @@ static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch, agg = cl->agg; /* if the queue was not empty, then done here */ - if (cl->qdisc->q.qlen != 1) { + if (!first) { if (unlikely(skb == cl->qdisc->ops->peek(cl->qdisc)) && list_first_entry(&agg->active, struct qfq_class, alist) == cl && cl->deficit < len) -- cgit v1.2.3