From 9aaf74440f72997257861fd12cde3a57b15a0126 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= Date: Wed, 31 Aug 2022 11:21:03 +0200 Subject: [PATCH] sch_cake: Return __NET_XMIT_STOLEN when consuming enqueued skb MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit [ Upstream commit f357f549d0df28a0a08d04d6c2a61538024c5038 ] When the GSO splitting feature of sch_cake is enabled, GSO superpackets will be broken up and the resulting segments enqueued in place of the original skb. In this case, CAKE calls consume_skb() on the original skb, but still returns NET_XMIT_SUCCESS. This can confuse parent qdiscs into assuming the original skb still exists, when it really has been freed. Fix this by adding the __NET_XMIT_STOLEN flag to the return value in this case. Fixes: 868a627f3168 ("sch_cake: Conditionally split GSO segments") Signed-off-by: Toke Høiland-Jørgensen Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-18231 Link: https://lore.kernel.org/r/20220831092103.442868-1-toke@toke.dk Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/sched/sch_cake.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/sched/sch_cake.c b/net/sched/sch_cake.c index 0eb4d4a568f77..737368c701c53 100644 --- a/net/sched/sch_cake.c +++ b/net/sched/sch_cake.c @@ -1677,6 +1677,7 @@ static s32 cake_enqueue(struct sk_buff *skb, struct Qdisc *sch, } idx--; flow = &b->flows[idx]; + ret = NET_XMIT_SUCCESS; /* ensure shaper state isn't stale */ if (!b->tin_backlog) { @@ -1737,6 +1738,7 @@ static s32 cake_enqueue(struct sk_buff *skb, struct Qdisc *sch, qdisc_tree_reduce_backlog(sch, 1-numsegs, len-slen); consume_skb(skb); + ret |= __NET_XMIT_STOLEN; } else { /* not splitting */ cobalt_set_enqueue_time(skb, now); @@ -1870,7 +1872,7 @@ static s32 cake_enqueue(struct sk_buff *skb, struct Qdisc *sch, } b->drop_overlimit += dropped; } - return NET_XMIT_SUCCESS; + return ret; } static struct sk_buff *cake_dequeue_one(struct Qdisc *sch) -- 2.39.5