[3.19.y-ckt stable] Patch "sched: cls_bpf: fix panic on filter replace" has been added to staging queue

[Kamal Mostafa]

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

    sched: cls_bpf: fix panic on filter replace

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 0e96590e67e42eb045cb347d6856e10f6441a856 Mon Sep 17 00:00:00 2001
From: Daniel Borkmann <daniel at iogearbox.net>
Date: Fri, 17 Jul 2015 22:38:43 +0200
Subject: sched: cls_bpf: fix panic on filter replace

commit f6bfc46da6292b630ba389592123f0dd02066172 upstream.

The following test case causes a NULL pointer dereference in cls_bpf:

  FOO="1,6 0 0 4294967295,"
  tc filter add dev foo parent 1: bpf bytecode "$FOO" flowid 1:1 action ok
  tc filter replace dev foo parent 1: pref 49152 handle 0x1 \
            bpf bytecode "$FOO" flowid 1:1 action drop

The problem is that commit 1f947bf151e9 ("net: sched: rcu'ify cls_bpf")
accidentally swapped the arguments of list_replace_rcu(), the old
element needs to be the first argument and the new element the second.

Fixes: 1f947bf151e9 ("net: sched: rcu'ify cls_bpf")
Signed-off-by: Daniel Borkmann <daniel at iogearbox.net>
Acked-by: John Fastabend <john.r.fastabend at intel.com>
Acked-by: Alexei Starovoitov <ast at plumgrid.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 net/sched/cls_bpf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c
index f59adf8..7ef71a2 100644
--- a/net/sched/cls_bpf.c
+++ b/net/sched/cls_bpf.c
@@ -282,7 +282,7 @@ static int cls_bpf_change(struct net *net, struct sk_buff *in_skb,
 		goto errout;

 	if (oldprog) {
-		list_replace_rcu(&prog->link, &oldprog->link);
+		list_replace_rcu(&oldprog->link, &prog->link);
 		tcf_unbind_filter(tp, &oldprog->res);
 		call_rcu(&oldprog->rcu, __cls_bpf_delete_prog);
 	} else {
--
1.9.1