linux-kernel - [PATCH 1/1] IPVS: Fix use-after-free issue in ip_vs_unbind

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]

Message-Id: <20250908065458.536-1-slavin452@gmail.com>
Date: Mon,  8 Sep 2025 14:54:58 +0800
From: Slavin Liu <slavin452@...il.com>
To: Simon Horman <horms@...ge.net.au>,
	Julian Anastasov <ja@....bg>
Cc: Slavin Liu <slavin452@...il.com>,
	Pablo Neira Ayuso <pablo@...filter.org>,
	Jozsef Kadlecsik <kadlec@...filter.org>,
	Florian Westphal <fw@...len.de>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	lvs-devel@...r.kernel.org,
	netdev@...r.kernel.org,
	netfilter-devel@...r.kernel.org,
	coreteam@...filter.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/1] IPVS: Fix use-after-free issue in ip_vs_unbind_app()

When exiting a network namespace, in cleanup_net()->ops_undo_list(),
ip_vs_ftp_ops->exit() is called before ip_vs_core_ops->exit_batch().
The ip_vs_app ip_vs_ftp and its incarnations will be freed by unregister_ip_vs_app().
However, there could still be connections bound to ip_vs_ftp's incarnation.
cp->app points to the free'd incarnation, which will be accessed later by
__ip_vs_cleanup_batch()->ip_vs_conn_net_cleanup()->ip_vs_conn_flush()->ip_vs_conn_del()->
ip_vs_conn_expire()->ip_vs_unbind_app(), causing a uaf. This vulnarability can
lead to a local privilege escalation.

Reproduction steps:
1. create a ipvs service on (127.0.0.1:21)
2. create a ipvs destination on the service, to (127.0.0.1:<any>)
3. send a tcp packet to (127.0.0.1:21)
4. exit the network namespace

I think the fix should flush all connection to ftp before unregistration.
The simpler fix is to delete ip_vs_ftp_ops->exit, and defer the unregistration
of ip_vs_ftp to ip_vs_app_net_cleanup(), which will unregister all ip_vs_app.
It's after ip_vs_conn_net_cleanup() so there is no uaf issue. This patch
seems to solve the issue but has't been fully tested yet, and is also not graceful.

Signed-off-by: Slavin Liu <slavin452@...il.com>
---
 net/netfilter/ipvs/ip_vs_ftp.c | 13 -------------
 1 file changed, 13 deletions(-)

diff --git a/net/netfilter/ipvs/ip_vs_ftp.c b/net/netfilter/ipvs/ip_vs_ftp.c
index d8a284999544..68def1106681 100644
--- a/net/netfilter/ipvs/ip_vs_ftp.c
+++ b/net/netfilter/ipvs/ip_vs_ftp.c
@@ -598,22 +598,9 @@ static int __net_init __ip_vs_ftp_init(struct net *net)
 	unregister_ip_vs_app(ipvs, &ip_vs_ftp);
 	return ret;
 }
-/*
- *	netns exit
- */
-static void __ip_vs_ftp_exit(struct net *net)
-{
-	struct netns_ipvs *ipvs = net_ipvs(net);
-
-	if (!ipvs)
-		return;
-
-	unregister_ip_vs_app(ipvs, &ip_vs_ftp);
-}

 static struct pernet_operations ip_vs_ftp_ops = {
 	.init = __ip_vs_ftp_init,
-	.exit = __ip_vs_ftp_exit,
 };

 static int __init ip_vs_ftp_init(void)
-- 
2.34.1