From patchwork Tue May 31 07:45:00 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Ziyang Xuan (William)" X-Patchwork-Id: 12865136 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CDE63C433EF for ; Tue, 31 May 2022 07:27:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244493AbiEaH1h (ORCPT ); Tue, 31 May 2022 03:27:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58898 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242971AbiEaH1g (ORCPT ); Tue, 31 May 2022 03:27:36 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7951A49F8E; Tue, 31 May 2022 00:27:33 -0700 (PDT) Received: from canpemm500006.china.huawei.com (unknown [172.30.72.56]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4LC3jq1T7VzjXBy; Tue, 31 May 2022 15:26:23 +0800 (CST) Received: from container.huawei.com (10.175.104.82) by canpemm500006.china.huawei.com (7.192.105.130) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 31 May 2022 15:27:29 +0800 From: Ziyang Xuan To: , , , , , CC: Subject: [PATCH net v2] macsec: fix UAF bug for real_dev Date: Tue, 31 May 2022 15:45:00 +0800 Message-ID: <20220531074500.1272846-1-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: dggems701-chm.china.huawei.com (10.3.19.178) To canpemm500006.china.huawei.com (7.192.105.130) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org Create a new macsec device but not get reference to real_dev. That can not ensure that real_dev is freed after macsec. That will trigger the UAF bug for real_dev as following: ================================================================== BUG: KASAN: use-after-free in macsec_get_iflink+0x5f/0x70 drivers/net/macsec.c:3662 Call Trace: ... macsec_get_iflink+0x5f/0x70 drivers/net/macsec.c:3662 dev_get_iflink+0x73/0xe0 net/core/dev.c:637 default_operstate net/core/link_watch.c:42 [inline] rfc2863_policy+0x233/0x2d0 net/core/link_watch.c:54 linkwatch_do_dev+0x2a/0x150 net/core/link_watch.c:161 Allocated by task 22209: ... alloc_netdev_mqs+0x98/0x1100 net/core/dev.c:10549 rtnl_create_link+0x9d7/0xc00 net/core/rtnetlink.c:3235 veth_newlink+0x20e/0xa90 drivers/net/veth.c:1748 Freed by task 8: ... kfree+0xd6/0x4d0 mm/slub.c:4552 kvfree+0x42/0x50 mm/util.c:615 device_release+0x9f/0x240 drivers/base/core.c:2229 kobject_cleanup lib/kobject.c:673 [inline] kobject_release lib/kobject.c:704 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x1c8/0x540 lib/kobject.c:721 netdev_run_todo+0x72e/0x10b0 net/core/dev.c:10327 After commit faab39f63c1f ("net: allow out-of-order netdev unregistration") and commit e5f80fcf869a ("ipv6: give an IPv6 dev to blackhole_netdev"), we can add dev_hold_track() in macsec_dev_init() and dev_put_track() in macsec_free_netdev() to fix the problem. Fixes: 2bce1ebed17d ("macsec: fix refcnt leak in module exit routine") Reported-by: syzbot+d0e94b65ac259c29ce7a@syzkaller.appspotmail.com Signed-off-by: Ziyang Xuan --- v2: - Add kdoc for new member @dev_tracker. --- drivers/net/macsec.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/net/macsec.c b/drivers/net/macsec.c index 832f09ac075e..817577e713d7 100644 --- a/drivers/net/macsec.c +++ b/drivers/net/macsec.c @@ -99,6 +99,7 @@ struct pcpu_secy_stats { * struct macsec_dev - private data * @secy: SecY config * @real_dev: pointer to underlying netdevice + * @dev_tracker: refcount tracker for @real_dev reference * @stats: MACsec device stats * @secys: linked list of SecY's on the underlying device * @gro_cells: pointer to the Generic Receive Offload cell @@ -107,6 +108,7 @@ struct pcpu_secy_stats { struct macsec_dev { struct macsec_secy secy; struct net_device *real_dev; + netdevice_tracker dev_tracker; struct pcpu_secy_stats __percpu *stats; struct list_head secys; struct gro_cells gro_cells; @@ -3459,6 +3461,9 @@ static int macsec_dev_init(struct net_device *dev) if (is_zero_ether_addr(dev->broadcast)) memcpy(dev->broadcast, real_dev->broadcast, dev->addr_len); + /* Get macsec's reference to real_dev */ + dev_hold_track(real_dev, &macsec->dev_tracker, GFP_KERNEL); + return 0; } @@ -3704,6 +3709,8 @@ static void macsec_free_netdev(struct net_device *dev) free_percpu(macsec->stats); free_percpu(macsec->secy.tx_sc.stats); + /* Get rid of the macsec's reference to real_dev */ + dev_put_track(macsec->real_dev, &macsec->dev_tracker); } static void macsec_setup(struct net_device *dev)