sfq: fix sfq class stats handling (ee09b3c1) · Commits · 戴 / test

sfq_walk() runs without qdisc lock. By the time it selects a non empty hash slot and sfq_dump_class_stats() is run (with lock held), slot might have been freed : We then access q->slots[SFQ_EMPTY_SLOT], out of bounds, and crash in slot_queue_walk() On previous kernels, bug is here but out of bounds qs[SFQ_DEPTH] and allot[SFQ_DEPTH] are located in struct sfq_sched_data, so no illegal memory access happens, only possibly wrong data reported to user. Also, slot_dequeue_tail() should make sure slot skb chain is correctly terminated, or sfq_dump_class_stats() can access freed skbs. Signed-off-by:

Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/sched/sch_sfq.c

+11 −5

Original line number	Diff line number	Diff line
		@@ -281,6 +281,7 @@ static inline struct sk_buff slot_dequeue_tail(struct sfq_slot slot)
		struct sk_buff *skb = slot->skblist_prev;

		slot->skblist_prev = skb->prev;
		skb->prev->next = (struct sk_buff *)slot;
		skb->next = skb->prev = NULL;
		return skb;
		}
		@@ -608,14 +609,19 @@ static int sfq_dump_class_stats(struct Qdisc *sch, unsigned long cl,
		struct gnet_dump *d)
		{
		struct sfq_sched_data *q = qdisc_priv(sch);
		const struct sfq_slot *slot = &q->slots[q->ht[cl - 1]];
		struct gnet_stats_queue qs = { .qlen = slot->qlen };
		struct tc_sfq_xstats xstats = { .allot = slot->allot };
		sfq_index idx = q->ht[cl - 1];
		struct gnet_stats_queue qs = { 0 };
		struct tc_sfq_xstats xstats = { 0 };
		struct sk_buff *skb;

		if (idx != SFQ_EMPTY_SLOT) {
		const struct sfq_slot *slot = &q->slots[idx];

		xstats.allot = slot->allot;
		qs.qlen = slot->qlen;
		slot_queue_walk(slot, skb)
		qs.backlog += qdisc_pkt_len(skb);

		}
		if (gnet_stats_copy_queue(d, &qs) < 0)
		return -1;
		return gnet_stats_copy_app(d, &xstats, sizeof(xstats));

Admin message