netdev - [PATCH] net_sched: cls_route: remove from list when handle is 0

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:   Tue,  9 Aug 2022 14:05:18 -0300
From:   Thadeu Lima de Souza Cascardo <cascardo@...onical.com>
To:     netdev@...r.kernel.org
Cc:     Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jiri Pirko <jiri@...nulli.us>,
        Thadeu Lima de Souza Cascardo <cascardo@...onical.com>,
        Zhenpeng Lin <zplin@...orthwestern.edu>,
        Kamal Mostafa <kamal@...onical.com>, stable@...r.kernel.org
Subject: [PATCH] net_sched: cls_route: remove from list when handle is 0

When a route filter is replaced and the old filter has a 0 handle, the old
one won't be removed from the hashtable, while it will still be freed.

The test was there since before commit 1109c00547fc ("net: sched: RCU
cls_route"), when a new filter was not allocated when there was an old one.
The old filter was reused and the reinserting would only be necessary if an
old filter was replaced. That was still wrong for the same case where the
old handle was 0.

Remove the old filter from the list independently from its handle value.

This fixes CVE-2022-2588, also reported as ZDI-CAN-17440.

Reported-by: Zhenpeng Lin <zplin@...orthwestern.edu>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@...onical.com>
Reviewed-by: Kamal Mostafa <kamal@...onical.com>
Cc: <stable@...r.kernel.org>
Cc: Jamal Hadi Salim <jhs@...atatu.com>
---
 net/sched/cls_route.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sched/cls_route.c b/net/sched/cls_route.c
index a35ab8c27866..3f935cbbaff6 100644
--- a/net/sched/cls_route.c
+++ b/net/sched/cls_route.c
@@ -526,7 +526,7 @@ static int route4_change(struct net *net, struct sk_buff *in_skb,
 	rcu_assign_pointer(f->next, f1);
 	rcu_assign_pointer(*fp, f);

-	if (fold && fold->handle && f->handle != fold->handle) {
+	if (fold) {
 		th = to_hash(fold->handle);
 		h = from_hash(fold->handle >> 16);
 		b = rtnl_dereference(head->table[th]);
-- 
2.34.1