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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2010-12-22 22:39:59 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2010-12-22 22:39:59 +0300 |
| commit | ee09b3c1cff0335137dc1b146488e4352f640f13 (patch) | |
| tree | 4f21be5938205963ab73f8ca2ebdd0f4a65f8b17 /net/sched/sch_sfq.c | |
| parent | 503b1a529a6b62b31904bab4699752c523cf76b2 (diff) | |
| download | linux-ee09b3c1cff0335137dc1b146488e4352f640f13.tar.xz | |
sfq: fix sfq class stats handling
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>
Diffstat (limited to 'net/sched/sch_sfq.c')
| -rw-r--r-- | net/sched/sch_sfq.c | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c index 13322e8a0456..6a2f88fea6d8 100644 --- a/net/sched/sch_sfq.c +++ b/net/sched/sch_sfq.c @@ -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; - slot_queue_walk(slot, skb) - qs.backlog += qdisc_pkt_len(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)); |