From mboxrd@z Thu Jan 1 00:00:00 1970 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 AC735C433F5 for ; Thu, 28 Oct 2021 01:46:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8F9376113B for ; Thu, 28 Oct 2021 01:46:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229624AbhJ1BtI (ORCPT ); Wed, 27 Oct 2021 21:49:08 -0400 Received: from mail.kernel.org ([198.145.29.99]:58584 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229534AbhJ1BtI (ORCPT ); Wed, 27 Oct 2021 21:49:08 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id B93C46112E; Thu, 28 Oct 2021 01:46:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1635385602; bh=9v/qogVvRtwTOzakfqD0BtXZD94udqhLg0FwPipBrjQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=NpCgCqOGPsxDZyob3kk/15NgeGVT9LCNntWA+G5rwHLO9GmgXQHoGfYSIKzTef2Vn L3scnYlbCMP+zt4nSeUlfyhlYyTjaw3Pv5TtU+JFyEWFq0o1QrMzNc0k8W0In1uJMn naQMEDHAH88iwyXNFB8DhZWTe05DY0Aui+g1eNMLATItpOPj+ANpZeaAKC3SctDxa2 QRSDel1gIBrlT5nEto5xpXzt3B9SAoGORTGB7V941R6bpTZDkd81HUFzl/l76bWle5 ft+neN3/PaxiZEeQ1BJ45ncO5pNnUeC9CEckaxoQhJKKJq7k8LpldI32f7qIFt+Aq+ c5083QskAJzsw== Date: Wed, 27 Oct 2021 18:46:40 -0700 From: Jakub Kicinski To: Ziyang Xuan Cc: , , , , linux-rdma@vger.kernel.org Subject: Re: [PATCH net] net: vlan: fix a UAF in vlan_dev_real_dev() Message-ID: <20211027184640.7955767e@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> In-Reply-To: <20211027121606.3300860-1-william.xuanziyang@huawei.com> References: <20211027121606.3300860-1-william.xuanziyang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Wed, 27 Oct 2021 20:16:06 +0800 Ziyang Xuan wrote: > 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; But will make all the callers of vlan_dev_real_dev() feel like they should NULL-check the result, which is not necessary. RDMA must be calling this helper on a vlan which was already unregistered, can we fix RDMA instead?