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 X-Spam-Level: X-Spam-Status: No, score=-22.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 81FB6C4338F for ; Mon, 23 Aug 2021 11:55:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 52C676103B for ; Mon, 23 Aug 2021 11:55:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236581AbhHWL4G (ORCPT ); Mon, 23 Aug 2021 07:56:06 -0400 Received: from out30-54.freemail.mail.aliyun.com ([115.124.30.54]:35462 "EHLO out30-54.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233684AbhHWL4F (ORCPT ); Mon, 23 Aug 2021 07:56:05 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R171e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04394;MF=xianting.tian@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0UlO1MIH_1629719720; Received: from B-LB6YLVDL-0141.local(mailfrom:xianting.tian@linux.alibaba.com fp:SMTPD_---0UlO1MIH_1629719720) by smtp.aliyun-inc.com(127.0.0.1); Mon, 23 Aug 2021 19:55:21 +0800 Subject: Re: [RESEND][PATCH] virtio_console: protect max_nr_ports to avoid invalid value To: amit@kernel.org, arnd@arndb.de, gregkh@linuxfoundation.org Cc: virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org References: <20210820075219.202404-1-xianting.tian@linux.alibaba.com> From: Xianting TIan Message-ID: <2746b7f2-2cd0-1042-3c36-b4392620525a@linux.alibaba.com> Date: Mon, 23 Aug 2021 19:55:20 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <20210820075219.202404-1-xianting.tian@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Could I get comments for the patch? thanks Is the value of  MAX_NR_PORTS accurate? this fix is similar to below patches, which are megered recently, https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.14-rc7&id=63947b3434f475418b9677a393d025c0962c2cf8 https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.14-rc7&id=82e89ea077b93b3c131fa175b0df3acb5b1d5cdf https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.14-rc7&id=d00d8da5869a2608e97cfede094dfc5e11462a46 在 2021/8/20 下午3:52, Xianting Tian 写道: > In theory untrusted remote host can pass a big or overflow value > of max_nr_ports to guest, it may cause guest system consumes > a lot of memory when create vqs and other impacts. > > Add the protection to guarantee max_nr_ports to get a safe value. > > Signed-off-by: Xianting Tian > --- > drivers/char/virtio_console.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c > index 7eaf303a7..bba985c81 100644 > --- a/drivers/char/virtio_console.c > +++ b/drivers/char/virtio_console.c > @@ -29,6 +29,8 @@ > > #define is_rproc_enabled IS_ENABLED(CONFIG_REMOTEPROC) > > +#define MAX_NR_PORTS MAX_NR_HVC_CONSOLES > + > /* > * This is a global struct for storing common data for all the devices > * this driver handles. > @@ -2039,6 +2041,9 @@ static int virtcons_probe(struct virtio_device *vdev) > multiport = true; > } > > + /* limit max_nr_ports to avoid invalid value from untrusted remote host */ > + portdev->max_nr_ports = min_t(u32, portdev->max_nr_ports, MAX_NR_PORTS); > + > err = init_vqs(portdev); > if (err < 0) { > dev_err(&vdev->dev, "Error %d initializing vqs\n", err);