From: Toke Høiland-Jørgensen toke@toke.dk
[ Upstream commit 90fabae8a2c225c4e4936723c38857887edde5cc ]
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: 0c850344d388 ("sch_cake: Conditionally split GSO segments") Signed-off-by: Toke Høiland-Jørgensen toke@toke.dk 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 kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 a43a58a73d096..a04928082e4ab 100644 --- a/net/sched/sch_cake.c +++ b/net/sched/sch_cake.c @@ -1713,6 +1713,7 @@ 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) { @@ -1771,6 +1772,7 @@ 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); @@ -1904,7 +1906,7 @@ 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)