[3.19.y-ckt stable] Patch "fq_codel: fix a use-after-free" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    fq_codel: fix a use-after-free

to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue

This patch is scheduled to be released in version 3.19.8-ckt6.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From f6ebcf17a2227b6f5c1ab9b1b63fa68d5beb9fc8 Mon Sep 17 00:00:00 2001
From: WANG Cong <xiyou.wangcong at gmail.com>
Date: Mon, 13 Jul 2015 12:30:07 -0700
Subject: fq_codel: fix a use-after-free

commit 052cbda41fdc243a8d40cce7ab3a6327b4b2887e upstream.

Fixes: 25331d6ce42b ("net: sched: implement qstat helper routines")
Cc: John Fastabend <john.fastabend at gmail.com>
Signed-off-by: Cong Wang <xiyou.wangcong at gmail.com>
Signed-off-by: Cong Wang <cwang at twopensource.com>
Acked-by: Eric Dumazet <edumazet at google.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 net/sched/sch_fq_codel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sched/sch_fq_codel.c b/net/sched/sch_fq_codel.c
index 1e52dec..b61fd84 100644
--- a/net/sched/sch_fq_codel.c
+++ b/net/sched/sch_fq_codel.c
@@ -162,10 +162,10 @@ static unsigned int fq_codel_drop(struct Qdisc *sch)
 	skb = dequeue_head(flow);
 	len = qdisc_pkt_len(skb);
 	q->backlogs[idx] -= len;
-	kfree_skb(skb);
 	sch->q.qlen--;
 	qdisc_qstats_drop(sch);
 	qdisc_qstats_backlog_dec(sch, skb);
+	kfree_skb(skb);
 	flow->dropped++;
 	return idx;
 }
--
1.9.1