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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 649C5C433DB for ; Fri, 12 Mar 2021 01:38:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 17E0764F93 for ; Fri, 12 Mar 2021 01:38:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230341AbhCLBhw (ORCPT ); Thu, 11 Mar 2021 20:37:52 -0500 Received: from mga14.intel.com ([192.55.52.115]:25698 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229938AbhCLBhV (ORCPT ); Thu, 11 Mar 2021 20:37:21 -0500 IronPort-SDR: ETyV+qGn5b7VJ7gdlTO6dqA+G+gba9188HlPmMFJxlh3o/J7wJdRI5Q+QFdU7iA3hUsoNUOwOW +lvpXjY2Bx4Q== X-IronPort-AV: E=McAfee;i="6000,8403,9920"; a="188131759" X-IronPort-AV: E=Sophos;i="5.81,241,1610438400"; d="scan'208";a="188131759" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Mar 2021 17:37:19 -0800 IronPort-SDR: OsP2ibwKgbiZCIqHpXErOVIXZRVkTtMdPT12UsGVzETQmRDXrR+VJOSlZgGsslap/LW/zq0mWI Kz1nn2ibHYLg== X-IronPort-AV: E=Sophos;i="5.81,241,1610438400"; d="scan'208";a="410833620" Received: from lingshan-mobl5.ccr.corp.intel.com (HELO [10.254.208.46]) ([10.254.208.46]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Mar 2021 17:37:16 -0800 Subject: Re: [PATCH 1/2] vhost-vdpa: fix use-after-free of v->config_ctx To: Stefano Garzarella , virtualization@lists.linux-foundation.org Cc: Jason Wang , netdev@vger.kernel.org, "Michael S. Tsirkin" , linux-kernel@vger.kernel.org, kvm@vger.kernel.org References: <20210311135257.109460-1-sgarzare@redhat.com> <20210311135257.109460-2-sgarzare@redhat.com> From: "Zhu, Lingshan" Message-ID: <82e63dc0-7589-98f7-0ea5-dd86ce64949d@intel.com> Date: Fri, 12 Mar 2021 09:37:14 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <20210311135257.109460-2-sgarzare@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/11/2021 9:52 PM, Stefano Garzarella wrote: > When the 'v->config_ctx' eventfd_ctx reference is released we didn't > set it to NULL. So if the same character device (e.g. /dev/vhost-vdpa-0) > is re-opened, the 'v->config_ctx' is invalid and calling again > vhost_vdpa_config_put() causes use-after-free issues like the > following refcount_t underflow: > > refcount_t: underflow; use-after-free. > WARNING: CPU: 2 PID: 872 at lib/refcount.c:28 refcount_warn_saturate+0xae/0xf0 > RIP: 0010:refcount_warn_saturate+0xae/0xf0 > Call Trace: > eventfd_ctx_put+0x5b/0x70 > vhost_vdpa_release+0xcd/0x150 [vhost_vdpa] > __fput+0x8e/0x240 > ____fput+0xe/0x10 > task_work_run+0x66/0xa0 > exit_to_user_mode_prepare+0x118/0x120 > syscall_exit_to_user_mode+0x21/0x50 > ? __x64_sys_close+0x12/0x40 > do_syscall_64+0x45/0x50 > entry_SYSCALL_64_after_hwframe+0x44/0xae > > Fixes: 776f395004d8 ("vhost_vdpa: Support config interrupt in vdpa") > Cc: lingshan.zhu@intel.com > Cc: stable@vger.kernel.org > Signed-off-by: Stefano Garzarella > --- > drivers/vhost/vdpa.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c > index ef688c8c0e0e..00796e4ecfdf 100644 > --- a/drivers/vhost/vdpa.c > +++ b/drivers/vhost/vdpa.c > @@ -308,8 +308,10 @@ static long vhost_vdpa_get_vring_num(struct vhost_vdpa *v, u16 __user *argp) > > static void vhost_vdpa_config_put(struct vhost_vdpa *v) > { > - if (v->config_ctx) > + if (v->config_ctx) { > eventfd_ctx_put(v->config_ctx); > + v->config_ctx = NULL; > + } > } > > static long vhost_vdpa_set_config_call(struct vhost_vdpa *v, u32 __user *argp) Thanks Stefano! Reviewed-by: Zhu Lingshan