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Date: Mon, 7 Jan 2019 20:47:30 +0100
From: Toke Høiland-Jørgensen <toke@...e.dk>
To: netdev@...r.kernel.org
Cc: cake@...ts.bufferbloat.net,
Toke Høiland-Jørgensen <toke@...hat.com>
Subject: [PATCH 1/4] sched: Avoid dereferencing skb pointer after child enqueue
From: Toke Høiland-Jørgensen <toke@...hat.com>
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 <toke@...hat.com>
---
net/sched/sch_cbs.c | 3 ++-
net/sched/sch_drr.c | 3 ++-
net/sched/sch_dsmark.c | 3 ++-
net/sched/sch_hfsc.c | 5 ++---
net/sched/sch_htb.c | 3 ++-
net/sched/sch_prio.c | 3 ++-
net/sched/sch_qfq.c | 16 +++++++++-------
net/sched/sch_tbf.c | 3 ++-
8 files changed, 23 insertions(+), 16 deletions(-)
diff --git a/net/sched/sch_cbs.c b/net/sched/sch_cbs.c
index e689e11b6d0f..c6a502933fe7 100644
--- a/net/sched/sch_cbs.c
+++ b/net/sched/sch_cbs.c
@@ -88,13 +88,14 @@ static int cbs_child_enqueue(struct sk_buff *skb, struct Qdisc *sch,
struct Qdisc *child,
struct sk_buff **to_free)
{
+ unsigned int len = qdisc_pkt_len(skb);
int err;
err = child->ops->enqueue(skb, child, to_free);
if (err != NET_XMIT_SUCCESS)
return err;
- qdisc_qstats_backlog_inc(sch, skb);
+ sch->qstats.backlog += len;
sch->q.qlen++;
return NET_XMIT_SUCCESS;
diff --git a/net/sched/sch_drr.c b/net/sched/sch_drr.c
index cdebaed0f8cf..feaf47178653 100644
--- a/net/sched/sch_drr.c
+++ b/net/sched/sch_drr.c
@@ -350,6 +350,7 @@ static struct drr_class *drr_classify(struct sk_buff *skb, struct Qdisc *sch,
static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch,
struct sk_buff **to_free)
{
+ unsigned int len = qdisc_pkt_len(skb);
struct drr_sched *q = qdisc_priv(sch);
struct drr_class *cl;
int err = 0;
@@ -376,7 +377,7 @@ static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch,
cl->deficit = cl->quantum;
}
- qdisc_qstats_backlog_inc(sch, skb);
+ sch->qstats.backlog += len;
sch->q.qlen++;
return err;
}
diff --git a/net/sched/sch_dsmark.c b/net/sched/sch_dsmark.c
index f6f480784bc6..42471464ded3 100644
--- a/net/sched/sch_dsmark.c
+++ b/net/sched/sch_dsmark.c
@@ -199,6 +199,7 @@ static struct tcf_block *dsmark_tcf_block(struct Qdisc *sch, unsigned long cl,
static int dsmark_enqueue(struct sk_buff *skb, struct Qdisc *sch,
struct sk_buff **to_free)
{
+ unsigned int len = qdisc_pkt_len(skb);
struct dsmark_qdisc_data *p = qdisc_priv(sch);
int err;
@@ -271,7 +272,7 @@ static int dsmark_enqueue(struct sk_buff *skb, struct Qdisc *sch,
return err;
}
- qdisc_qstats_backlog_inc(sch, skb);
+ sch->qstats.backlog += len;
sch->q.qlen++;
return NET_XMIT_SUCCESS;
diff --git a/net/sched/sch_hfsc.c b/net/sched/sch_hfsc.c
index b18ec1f6de60..6bb8f73a8473 100644
--- a/net/sched/sch_hfsc.c
+++ b/net/sched/sch_hfsc.c
@@ -1539,6 +1539,7 @@ hfsc_dump_qdisc(struct Qdisc *sch, struct sk_buff *skb)
static int
hfsc_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free)
{
+ unsigned int len = qdisc_pkt_len(skb);
struct hfsc_class *cl;
int uninitialized_var(err);
@@ -1560,8 +1561,6 @@ hfsc_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free)
}
if (cl->qdisc->q.qlen == 1) {
- unsigned int len = qdisc_pkt_len(skb);
-
if (cl->cl_flags & HFSC_RSC)
init_ed(cl, len);
if (cl->cl_flags & HFSC_FSC)
@@ -1576,7 +1575,7 @@ hfsc_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free)
}
- qdisc_qstats_backlog_inc(sch, skb);
+ sch->qstats.backlog += len;
sch->q.qlen++;
return NET_XMIT_SUCCESS;
diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 58b449490757..30f9da7e1076 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -581,6 +581,7 @@ static int htb_enqueue(struct sk_buff *skb, struct Qdisc *sch,
struct sk_buff **to_free)
{
int uninitialized_var(ret);
+ unsigned int len = qdisc_pkt_len(skb);
struct htb_sched *q = qdisc_priv(sch);
struct htb_class *cl = htb_classify(skb, sch, &ret);
@@ -610,7 +611,7 @@ static int htb_enqueue(struct sk_buff *skb, struct Qdisc *sch,
htb_activate(q, cl);
}
- qdisc_qstats_backlog_inc(sch, skb);
+ sch->qstats.backlog += len;
sch->q.qlen++;
return NET_XMIT_SUCCESS;
}
diff --git a/net/sched/sch_prio.c b/net/sched/sch_prio.c
index cdf68706e40f..847141cd900f 100644
--- a/net/sched/sch_prio.c
+++ b/net/sched/sch_prio.c
@@ -72,6 +72,7 @@ prio_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr)
static int
prio_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free)
{
+ unsigned int len = qdisc_pkt_len(skb);
struct Qdisc *qdisc;
int ret;
@@ -88,7 +89,7 @@ prio_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free)
ret = qdisc_enqueue(skb, qdisc, to_free);
if (ret == NET_XMIT_SUCCESS) {
- qdisc_qstats_backlog_inc(sch, skb);
+ sch->qstats.backlog += len;
sch->q.qlen++;
return NET_XMIT_SUCCESS;
}
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;
diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c
index 942dcca09cf2..7f272a9070c5 100644
--- a/net/sched/sch_tbf.c
+++ b/net/sched/sch_tbf.c
@@ -185,6 +185,7 @@ static int tbf_enqueue(struct sk_buff *skb, struct Qdisc *sch,
struct sk_buff **to_free)
{
struct tbf_sched_data *q = qdisc_priv(sch);
+ unsigned int len = qdisc_pkt_len(skb);
int ret;
if (qdisc_pkt_len(skb) > q->max_size) {
@@ -200,7 +201,7 @@ static int tbf_enqueue(struct sk_buff *skb, struct Qdisc *sch,
return ret;
}
- qdisc_qstats_backlog_inc(sch, skb);
+ sch->qstats.backlog += len;
sch->q.qlen++;
return NET_XMIT_SUCCESS;
}
--
2.20.1
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