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 08C42C433F5 for ; Wed, 15 Dec 2021 17:26:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245649AbhLOR00 (ORCPT ); Wed, 15 Dec 2021 12:26:26 -0500 Received: from ams.source.kernel.org ([145.40.68.75]:42340 "EHLO ams.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245648AbhLORZB (ORCPT ); Wed, 15 Dec 2021 12:25:01 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 5A58CB82029; Wed, 15 Dec 2021 17:25:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9D0F9C36AE2; Wed, 15 Dec 2021 17:24:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1639589099; bh=14PYgjOPcuznMxdJlqia4LIKiz+cpLfgtJRpyJVX5TE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cM0jaSbL4xa5nVdGEK5IVMLcGW94KPHYFS7SP3JpFUU4Ovtd2q2uoOppfP1iDjG+p ur8shT2ffiNKWzd36ukckKcx/D4wor3W12N8/pWjpViqRhx/DdGQFBOBfDYizQs3iQ mRsQUJRgVRxRR/zjLX4PTQNujU75Qi+LGTom00JA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jakub Kicinski , Antoine Tenart Subject: [PATCH 5.10 20/33] ethtool: do not perform operations on net devices being unregistered Date: Wed, 15 Dec 2021 18:21:18 +0100 Message-Id: <20211215172025.469159159@linuxfoundation.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20211215172024.787958154@linuxfoundation.org> References: <20211215172024.787958154@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Antoine Tenart commit dde91ccfa25fd58f64c397d91b81a4b393100ffa upstream. There is a short period between a net device starts to be unregistered and when it is actually gone. In that time frame ethtool operations could still be performed, which might end up in unwanted or undefined behaviours[1]. Do not allow ethtool operations after a net device starts its unregistration. This patch targets the netlink part as the ioctl one isn't affected: the reference to the net device is taken and the operation is executed within an rtnl lock section and the net device won't be found after unregister. [1] For example adding Tx queues after unregister ends up in NULL pointer exceptions and UaFs, such as: BUG: KASAN: use-after-free in kobject_get+0x14/0x90 Read of size 1 at addr ffff88801961248c by task ethtool/755 CPU: 0 PID: 755 Comm: ethtool Not tainted 5.15.0-rc6+ #778 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-4.fc34 04/014 Call Trace: dump_stack_lvl+0x57/0x72 print_address_description.constprop.0+0x1f/0x140 kasan_report.cold+0x7f/0x11b kobject_get+0x14/0x90 kobject_add_internal+0x3d1/0x450 kobject_init_and_add+0xba/0xf0 netdev_queue_update_kobjects+0xcf/0x200 netif_set_real_num_tx_queues+0xb4/0x310 veth_set_channels+0x1c3/0x550 ethnl_set_channels+0x524/0x610 Fixes: 041b1c5d4a53 ("ethtool: helper functions for netlink interface") Suggested-by: Jakub Kicinski Signed-off-by: Antoine Tenart Link: https://lore.kernel.org/r/20211203101318.435618-1-atenart@kernel.org Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/ethtool/netlink.h | 3 +++ 1 file changed, 3 insertions(+) --- a/net/ethtool/netlink.h +++ b/net/ethtool/netlink.h @@ -249,6 +249,9 @@ struct ethnl_reply_data { static inline int ethnl_ops_begin(struct net_device *dev) { + if (dev && dev->reg_state == NETREG_UNREGISTERING) + return -ENODEV; + if (dev && dev->ethtool_ops->begin) return dev->ethtool_ops->begin(dev); else