netem: fix possible NULL deref in netem_dequeue()
commit aec0a40a6f7884 ("netem: use rb tree to implement the time queue")
added a regression if a child qdisc is attached to netem, as we perform
a NULL dereference.
Fix this by adding a temporary variable to cache
netem_skb_cb(skb)->time_to_send.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index ed0082c..82f6016 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -554,10 +554,13 @@
}
p = rb_first(&q->t_root);
if (p) {
+ psched_time_t time_to_send;
+
skb = netem_rb_to_skb(p);
/* if more time remaining? */
- if (netem_skb_cb(skb)->time_to_send <= psched_get_time()) {
+ time_to_send = netem_skb_cb(skb)->time_to_send;
+ if (time_to_send <= psched_get_time()) {
rb_erase(p, &q->t_root);
sch->q.qlen--;
@@ -593,8 +596,7 @@
if (skb)
goto deliver;
}
- qdisc_watchdog_schedule(&q->watchdog,
- netem_skb_cb(skb)->time_to_send);
+ qdisc_watchdog_schedule(&q->watchdog, time_to_send);
}
if (q->qdisc) {
