net/sched: sch_qfq: Fix null-deref in agg_dequeue

commit dd831ac8221e691e9e918585b1003c7071df0379 upstream.

To prevent a potential crash in agg_dequeue (net/sched/sch_qfq.c)
when cl->qdisc->ops->peek(cl->qdisc) returns NULL, we check the return
value before using it, similar to the existing approach in sch_hfsc.c.

To avoid code duplication, the following changes are made:

1. Changed qdisc_warn_nonwc(include/net/pkt_sched.h) into a static
inline function.

2. Moved qdisc_peek_len from net/sched/sch_hfsc.c to
include/net/pkt_sched.h so that sch_qfq can reuse it.

3. Applied qdisc_peek_len in agg_dequeue to avoid crashing.

Signed-off-by: Xiang Mei <xmei5@asu.edu>
Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com>
Link: https://patch.msgid.link/20250705212143.3982664-1-xmei5@asu.edu
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Xiang Mei 2025-07-05 14:21:43 -07:00 • committed by Greg Kroah-Hartman
commit 71d84658a6
4 changed files with 25 additions and 28 deletions

View file

@ -109,7 +109,6 @@ struct qdisc_rate_table *qdisc_get_rtab(struct tc_ratespec *r,
struct netlink_ext_ack *extack);
void qdisc_put_rtab(struct qdisc_rate_table *tab);
void qdisc_put_stab(struct qdisc_size_table *tab);
void qdisc_warn_nonwc(const char *txt, struct Qdisc *qdisc);
bool sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
struct net_device *dev, struct netdev_queue *txq,
spinlock_t *root_lock, bool validate);
@ -176,4 +175,28 @@ struct tc_taprio_qopt_offload *taprio_offload_get(struct tc_taprio_qopt_offload
*offload);
void taprio_offload_free(struct tc_taprio_qopt_offload *offload);
static inline void qdisc_warn_nonwc(const char *txt, struct Qdisc *qdisc)
{
if (!(qdisc->flags & TCQ_F_WARN_NONWC)) {
pr_warn("%s: %s qdisc %X: is non-work-conserving?\n",
txt, qdisc->ops->id, qdisc->handle >> 16);
qdisc->flags |= TCQ_F_WARN_NONWC;
}
}
static inline unsigned int qdisc_peek_len(struct Qdisc *sch)
{
struct sk_buff *skb;
unsigned int len;
skb = sch->ops->peek(sch);
if (unlikely(skb == NULL)) {
qdisc_warn_nonwc("qdisc_peek_len", sch);
return 0;
}
len = qdisc_pkt_len(skb);
return len;
}
#endif

View file

@ -592,16 +592,6 @@ out:
qdisc_skb_cb(skb)->pkt_len = pkt_len;
}
void qdisc_warn_nonwc(const char *txt, struct Qdisc *qdisc)
{
if (!(qdisc->flags & TCQ_F_WARN_NONWC)) {
pr_warn("%s: %s qdisc %X: is non-work-conserving?\n",
txt, qdisc->ops->id, qdisc->handle >> 16);
qdisc->flags |= TCQ_F_WARN_NONWC;
}
}
EXPORT_SYMBOL(qdisc_warn_nonwc);
static enum hrtimer_restart qdisc_watchdog(struct hrtimer *timer)
{
struct qdisc_watchdog *wd = container_of(timer, struct qdisc_watchdog,

View file

@ -836,22 +836,6 @@ update_vf(struct hfsc_class *cl, unsigned int len, u64 cur_time)
}
}
static unsigned int
qdisc_peek_len(struct Qdisc *sch)
{
struct sk_buff *skb;
unsigned int len;
skb = sch->ops->peek(sch);
if (unlikely(skb == NULL)) {
qdisc_warn_nonwc("qdisc_peek_len", sch);
return 0;
}
len = qdisc_pkt_len(skb);
return len;
}
static void
hfsc_adjust_levels(struct hfsc_class *cl)
{

View file

@ -1003,7 +1003,7 @@ static struct sk_buff *agg_dequeue(struct qfq_aggregate *agg,
if (cl->qdisc->q.qlen == 0) /* no more packets, remove from list */
list_del_init(&cl->alist);
else if (cl->deficit < qdisc_pkt_len(cl->qdisc->ops->peek(cl->qdisc))) {
else if (cl->deficit < qdisc_peek_len(cl->qdisc)) {
cl->deficit += agg->lmax;
list_move_tail(&cl->alist, &agg->active);
}