summaryrefslogtreecommitdiff
path: root/net/sched/sch_generic.c
diff options
context:
space:
mode:
authorEric Dumazet <edumazet@google.com>2018-03-14 18:53:00 -0700
committerDavid S. Miller <davem@davemloft.net>2018-03-17 17:03:45 -0400
commitcce6294cc2eaa083482e1d85d8db5845c82a7e14 (patch)
treea067ed90ac97c73c1ab5d924a3dbef9906cbcc13 /net/sched/sch_generic.c
parent7b7ef57c0dd2bb367ad41a77e5136c5579ae4026 (diff)
downloadlinux-sh-cce6294cc2eaa083482e1d85d8db5845c82a7e14.tar.gz
net: sched: fix uses after free
syzbot reported one use-after-free in pfifo_fast_enqueue() [1] Issue here is that we can not reuse skb after a successful skb_array_produce() since another cpu might have consumed it already. I believe a similar problem exists in try_bulk_dequeue_skb_slow() in case we put an skb into qdisc_enqueue_skb_bad_txq() for lockless qdisc. [1] BUG: KASAN: use-after-free in qdisc_pkt_len include/net/sch_generic.h:610 [inline] BUG: KASAN: use-after-free in qdisc_qstats_cpu_backlog_inc include/net/sch_generic.h:712 [inline] BUG: KASAN: use-after-free in pfifo_fast_enqueue+0x4bc/0x5e0 net/sched/sch_generic.c:639 Read of size 4 at addr ffff8801cede37e8 by task syzkaller717588/5543 CPU: 1 PID: 5543 Comm: syzkaller717588 Not tainted 4.16.0-rc4+ #265 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x24d lib/dump_stack.c:53 print_address_description+0x73/0x250 mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report+0x23c/0x360 mm/kasan/report.c:412 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:432 qdisc_pkt_len include/net/sch_generic.h:610 [inline] qdisc_qstats_cpu_backlog_inc include/net/sch_generic.h:712 [inline] pfifo_fast_enqueue+0x4bc/0x5e0 net/sched/sch_generic.c:639 __dev_xmit_skb net/core/dev.c:3216 [inline] Fixes: c5ad119fb6c0 ("net: sched: pfifo_fast use skb_array") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot+ed43b6903ab968b16f54@syzkaller.appspotmail.com Cc: John Fastabend <john.fastabend@gmail.com> Cc: Jamal Hadi Salim <jhs@mojatatu.com> Cc: Cong Wang <xiyou.wangcong@gmail.com> Cc: Jiri Pirko <jiri@resnulli.us> Acked-by: John Fastabend <john.fastabend@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sched/sch_generic.c')
-rw-r--r--net/sched/sch_generic.c22
1 files changed, 13 insertions, 9 deletions
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 190570f21b20..7e3fbe9cc936 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -106,6 +106,14 @@ static inline void qdisc_enqueue_skb_bad_txq(struct Qdisc *q,
__skb_queue_tail(&q->skb_bad_txq, skb);
+ if (qdisc_is_percpu_stats(q)) {
+ qdisc_qstats_cpu_backlog_inc(q, skb);
+ qdisc_qstats_cpu_qlen_inc(q);
+ } else {
+ qdisc_qstats_backlog_inc(q, skb);
+ q->q.qlen++;
+ }
+
if (lock)
spin_unlock(lock);
}
@@ -196,14 +204,6 @@ static void try_bulk_dequeue_skb_slow(struct Qdisc *q,
break;
if (unlikely(skb_get_queue_mapping(nskb) != mapping)) {
qdisc_enqueue_skb_bad_txq(q, nskb);
-
- if (qdisc_is_percpu_stats(q)) {
- qdisc_qstats_cpu_backlog_inc(q, nskb);
- qdisc_qstats_cpu_qlen_inc(q);
- } else {
- qdisc_qstats_backlog_inc(q, nskb);
- q->q.qlen++;
- }
break;
}
skb->next = nskb;
@@ -628,6 +628,7 @@ static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
int band = prio2band[skb->priority & TC_PRIO_MAX];
struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
struct skb_array *q = band2list(priv, band);
+ unsigned int pkt_len = qdisc_pkt_len(skb);
int err;
err = skb_array_produce(q, skb);
@@ -636,7 +637,10 @@ static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc,
return qdisc_drop_cpu(skb, qdisc, to_free);
qdisc_qstats_cpu_qlen_inc(qdisc);
- qdisc_qstats_cpu_backlog_inc(qdisc, skb);
+ /* Note: skb can not be used after skb_array_produce(),
+ * so we better not use qdisc_qstats_cpu_backlog_inc()
+ */
+ this_cpu_add(qdisc->cpu_qstats->backlog, pkt_len);
return NET_XMIT_SUCCESS;
}