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: <20180823075506.506080563@linuxfoundation.org>
Date:   Thu, 23 Aug 2018 09:52:14 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Gao Feng <gfree.wind@....163.com>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.14 021/217] netfilter: nf_ct_helper: Fix possible panic after nf_conntrack_helper_unregister

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Gao Feng <gfree.wind@....163.com>

[ Upstream commit ad9852af97587b8abe8102f9ddcb05c9769656f6 ]

The helper module would be unloaded after nf_conntrack_helper_unregister,
so it may cause a possible panic caused by race.

nf_ct_iterate_destroy(unhelp, me) reset the helper of conntrack as NULL,
but maybe someone has gotten the helper pointer during this period. Then
it would panic, when it accesses the helper and the module was unloaded.

Take an example as following:
CPU0                                                   CPU1
ctnetlink_dump_helpinfo
helper = rcu_dereference(help->helper);
                                                       unhelp
                                                       set helper as NULL
                                                       unload helper module
helper->to_nlattr(skb, ct);

As above, the cpu0 tries to access the helper and its module is unloaded,
then the panic happens.

Signed-off-by: Gao Feng <gfree.wind@....163.com>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/netfilter/nf_conntrack_helper.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/net/netfilter/nf_conntrack_helper.c
+++ b/net/netfilter/nf_conntrack_helper.c
@@ -465,6 +465,11 @@ void nf_conntrack_helper_unregister(stru
 
 	nf_ct_expect_iterate_destroy(expect_iter_me, NULL);
 	nf_ct_iterate_destroy(unhelp, me);
+
+	/* Maybe someone has gotten the helper already when unhelp above.
+	 * So need to wait it.
+	 */
+	synchronize_rcu();
 }
 EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister);
 


Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ