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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 2A7FCC55182 for ; Mon, 20 Apr 2020 22:41:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F3E5A20672 for ; Mon, 20 Apr 2020 22:41:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="jHw+hnRA" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727794AbgDTWlp (ORCPT ); Mon, 20 Apr 2020 18:41:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42756 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725958AbgDTWlm (ORCPT ); Mon, 20 Apr 2020 18:41:42 -0400 Received: from mail-pj1-x1041.google.com (mail-pj1-x1041.google.com [IPv6:2607:f8b0:4864:20::1041]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7199AC061A0C for ; Mon, 20 Apr 2020 15:41:42 -0700 (PDT) Received: by mail-pj1-x1041.google.com with SMTP id e6so504462pjt.4 for ; Mon, 20 Apr 2020 15:41:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=AOx/Nk4FquXJyWXQfptpC4DSa3mcXsVlsvT6l/XeQck=; b=jHw+hnRA6zoSySOMYOCCKdmQTQ1cfELgXOG3Ih3ugNGr6GP3hDbhtn0NUs1uN7CGYx ZFs4j8Mc/Y/pPEdRTARWyj+usqUYGY++8v8et5dLO0wsnPoCjEk6nadlBBCbO8ENnU1i b8lbCArlNcDy0C9Z1f1lknHGNDWrdN497MMzM= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=AOx/Nk4FquXJyWXQfptpC4DSa3mcXsVlsvT6l/XeQck=; b=Pi7EwVlQPgvY/UwQRBa2T5DuLbBexRIfuHeCLOnw+R8Bg0ojf+Daq/suXHvK7Rrxpp BdSnthilv7DyxO6IkAxobKCWAeX1bU9nIKYSgpvyVch/iDkhwW29a/aT4Mdfrko81sSO g61Jt5kZxgAgmlK8393I5G2HtVMJILbkGk0dtCgxIyoFRLMsPjd3eS1AFC27xaEauppr 1FPTZdHf0U5I4MP+KZWp5n/pED+hP1n/pQj/D4E675cdQsqO07O+jJfFdf5DCk5buq3l CGay9ic/iWNufjCB7/IVjz40KW9dYtBL+HtU16OGRpWBsFfSnEO7lNYhM0BNpRKnoWnR jTSA== X-Gm-Message-State: AGi0PuZFduv+J7kCLwUa66T9k0coDmbyF5x7e/E34qiHHYv6qzPhcrVJ ZmerXVDKTpNSBWVWXRLo5VMhXA== X-Google-Smtp-Source: APiQypL5Z6q8UaSwVwqhWKDtZz7B9BBMwHt2OfgW1N+IC7mdxg5XMaIXwNjTPPsuJbbTL58HeQiluA== X-Received: by 2002:a17:90a:25cb:: with SMTP id k69mr1861715pje.93.1587422502023; Mon, 20 Apr 2020 15:41:42 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id j7sm442489pjy.9.2020.04.20.15.41.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Apr 2020 15:41:41 -0700 (PDT) Date: Mon, 20 Apr 2020 15:41:40 -0700 From: Kees Cook To: Andrew Morton Cc: glider@google.com, adobriyan@gmail.com, linux-kernel@vger.kernel.org, sunhaoyl@outlook.com Subject: Re: [PATCH] fs/binfmt_elf.c: allocate initialized memory in fill_thread_core_info() Message-ID: <202004201540.01C8F82B@keescook> References: <20200419100848.63472-1-glider@google.com> <20200420153352.6682533e794f591dae7aafbc@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200420153352.6682533e794f591dae7aafbc@linux-foundation.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 20, 2020 at 03:33:52PM -0700, Andrew Morton wrote: > On Sun, 19 Apr 2020 12:08:48 +0200 glider@google.com wrote: > > > KMSAN reported uninitialized data being written to disk when dumping > > core. As a result, several kilobytes of kmalloc memory may be written to > > the core file and then read by a non-privileged user. Ewww. That's been there for 12 years. Did something change in regset_size() or regset->get()? Do you know what leaves the hole? > > > > ... > > > > --- a/fs/binfmt_elf.c > > +++ b/fs/binfmt_elf.c > > @@ -1733,7 +1733,7 @@ static int fill_thread_core_info(struct elf_thread_core_info *t, > > (!regset->active || regset->active(t->task, regset) > 0)) { > > int ret; > > size_t size = regset_size(t->task, regset); > > - void *data = kmalloc(size, GFP_KERNEL); > > + void *data = kzalloc(size, GFP_KERNEL); > > if (unlikely(!data)) > > return 0; > > ret = regset->get(t->task, regset, > > This seems to be a quite easy way of exposing quite a large amount of > kernel memory contents, so I think I'll add a cc:stable to this patch? Yes please. Acked-by: Kees Cook -Kees -- Kees Cook