netdev - [PATCH net v2 1/3] net/sched: cls_u32: No longer copy tcf

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

Message-Id: <20230729123202.72406-2-jhs@mojatatu.com>
Date: Sat, 29 Jul 2023 08:32:00 -0400
From: Jamal Hadi Salim <jhs@...atatu.com>
To: davem@...emloft.net,
	kuba@...nel.org,
	edumazet@...gle.com,
	pabeni@...hat.com
Cc: jiri@...nulli.us,
	xiyou.wangcong@...il.com,
	netdev@...r.kernel.org,
	sec@...is.email,
	ramdhan@...rlabs.sg,
	billy@...rlabs.sg,
	Jamal Hadi Salim <jhs@...atatu.com>
Subject: [PATCH net v2 1/3] net/sched: cls_u32: No longer copy tcf_result on update to avoid use-after-free

From: valis <sec@...is.email>

When u32_change() is called on an existing filter, the whole
tcf_result struct is always copied into the new instance of the filter.

This causes a problem when updating a filter bound to a class,
as tcf_unbind_filter() is always called on the old instance in the
success path, decreasing filter_cnt of the still referenced class
and allowing it to be deleted, leading to a use-after-free.

Fix this by no longer copying the tcf_result struct from the old filter.

Fixes: de5df63228fc ("net: sched: cls_u32 changes to knode must appear atomic to readers")
Reported-by: valis <sec@...is.email>
Reported-by: M A Ramdhan <ramdhan@...rlabs.sg>
Signed-off-by: valis <sec@...is.email>
Signed-off-by: Jamal Hadi Salim <jhs@...atatu.com>
---
 net/sched/cls_u32.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c
index 907e58841fe8..da4c179a4d41 100644
--- a/net/sched/cls_u32.c
+++ b/net/sched/cls_u32.c
@@ -826,7 +826,6 @@ static struct tc_u_knode *u32_init_knode(struct net *net, struct tcf_proto *tp,
 
 	new->ifindex = n->ifindex;
 	new->fshift = n->fshift;
-	new->res = n->res;
 	new->flags = n->flags;
 	RCU_INIT_POINTER(new->ht_down, ht);
 
-- 
2.34.1