From patchwork Wed Oct 27 12:16:06 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Ziyang Xuan (William)" X-Patchwork-Id: 12587113 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 18CD3C433F5 for ; Wed, 27 Oct 2021 11:58:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 01D636109E for ; Wed, 27 Oct 2021 11:58:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231847AbhJ0MAq (ORCPT ); Wed, 27 Oct 2021 08:00:46 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:14868 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236185AbhJ0MAp (ORCPT ); Wed, 27 Oct 2021 08:00:45 -0400 Received: from dggeml757-chm.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4HfRz82jdBz90Lv; Wed, 27 Oct 2021 19:58:12 +0800 (CST) Received: from localhost.localdomain (10.175.104.82) by dggeml757-chm.china.huawei.com (10.1.199.137) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2308.15; Wed, 27 Oct 2021 19:58:15 +0800 From: Ziyang Xuan To: , CC: , , Subject: [PATCH net] net: vlan: fix a UAF in vlan_dev_real_dev() Date: Wed, 27 Oct 2021 20:16:06 +0800 Message-ID: <20211027121606.3300860-1-william.xuanziyang@huawei.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Originating-IP: [10.175.104.82] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggeml757-chm.china.huawei.com (10.1.199.137) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org The real_dev of a vlan net_device may be freed after unregister_vlan_dev(). Access the real_dev continually by vlan_dev_real_dev() will trigger the UAF problem for the real_dev like following: ================================================================== BUG: KASAN: use-after-free in vlan_dev_real_dev+0xf9/0x120 Call Trace: kasan_report.cold+0x83/0xdf vlan_dev_real_dev+0xf9/0x120 is_eth_port_of_netdev_filter.part.0+0xb1/0x2c0 is_eth_port_of_netdev_filter+0x28/0x40 ib_enum_roce_netdev+0x1a3/0x300 ib_enum_all_roce_netdevs+0xc7/0x140 netdevice_event_work_handler+0x9d/0x210 ... Freed by task 9288: kasan_save_stack+0x1b/0x40 kasan_set_track+0x1c/0x30 kasan_set_free_info+0x20/0x30 __kasan_slab_free+0xfc/0x130 slab_free_freelist_hook+0xdd/0x240 kfree+0xe4/0x690 kvfree+0x42/0x50 device_release+0x9f/0x240 kobject_put+0x1c8/0x530 put_device+0x1b/0x30 free_netdev+0x370/0x540 ppp_destroy_interface+0x313/0x3d0 ... Set vlan->real_dev to NULL after dev_put(real_dev) in unregister_vlan_dev(). Check real_dev is not NULL before access it in vlan_dev_real_dev(). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot+e4df4e1389e28972e955@syzkaller.appspotmail.com Signed-off-by: Ziyang Xuan --- net/8021q/vlan.c | 1 + net/8021q/vlan_core.c | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c index 55275ef9a31a..1106da84e725 100644 --- a/net/8021q/vlan.c +++ b/net/8021q/vlan.c @@ -126,6 +126,7 @@ void unregister_vlan_dev(struct net_device *dev, struct list_head *head) /* Get rid of the vlan's reference to real_dev */ dev_put(real_dev); + vlan->real_dev = NULL; } int vlan_check_real_dev(struct net_device *real_dev, diff --git a/net/8021q/vlan_core.c b/net/8021q/vlan_core.c index 59bc13b5f14f..343f34479d8b 100644 --- a/net/8021q/vlan_core.c +++ b/net/8021q/vlan_core.c @@ -103,7 +103,7 @@ struct net_device *vlan_dev_real_dev(const struct net_device *dev) { struct net_device *ret = vlan_dev_priv(dev)->real_dev; - while (is_vlan_dev(ret)) + while (ret && is_vlan_dev(ret)) ret = vlan_dev_priv(ret)->real_dev; return ret;