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=-5.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 AC344C433E6 for ; Fri, 10 Jul 2020 22:10:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 871322068F for ; Fri, 10 Jul 2020 22:10:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=broadcom.com header.i=@broadcom.com header.b="HEBvePuV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726319AbgGJWKj (ORCPT ); Fri, 10 Jul 2020 18:10:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58686 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726602AbgGJWKi (ORCPT ); Fri, 10 Jul 2020 18:10:38 -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 932E4C08C5DC for ; Fri, 10 Jul 2020 15:10:38 -0700 (PDT) Received: by mail-pj1-x1041.google.com with SMTP id mn17so3178168pjb.4 for ; Fri, 10 Jul 2020 15:10:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=broadcom.com; s=google; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-transfer-encoding:content-language; bh=aibEP9PY7qjIXvWY9ybATGaYnLNWOzVMnBkuiR7TDf8=; b=HEBvePuVhen5zXWxLZJ5MAw3GFOvOn+W3aT7QHZHcK+np34JnSw3feprmqOcn1MN9x 4lfLK7rdc6DHLOHjgyBt/ym41ksnQK1EaXiNbS741pAYHB/MHGmGNEW0KfJUZLoAqui/ 3aWQJJlU6S2r8xMzEuTOkhCa581xCJayzSRAw= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=aibEP9PY7qjIXvWY9ybATGaYnLNWOzVMnBkuiR7TDf8=; b=ETn2zJxqPZco5owIrBMvvaZc6JxswjDeZ6un3m1LhpKmgRQGNbEVsZ54zWIxG5HDo5 lPUk95RRJ1etYewameQOfPoZTgAYANEWSPNQh63UhiBnYOE373sn2d74kuZ4ZNhyE9QA E2u/Cifvz7H/xmp6zfs6CQhOBnr3PmO0HYUT5PGqxyLpKGqBQem138gZiwLBVsRxr2Zi wersJF7H2Z1D3DKYJp6UZlLtdipKHYYwlTlz6TypwsCbumqRxyKt4Pb07MuyHKWkI/dd lZdIb/l3RmVGpWncPEdyoFoI81RoyGDpIr+6cfXJ1wHJa0vkCYd1++Tj2uSHTTJ/a6gt ZZUQ== X-Gm-Message-State: AOAM53328YwySBeQHUG98J9QwiCYkLJ7jzLH49/GjRPUJvgHGkvqHmI7 tRKvZOyM43gthlyDrHSyZksvP2mAPYpVeB5D+X6fNr+NvJorZB2IyQHoCMDV4jvcEzEEZOmTnC5 4zKso/ywYik2Uxgnuk6e32sfmGEJEwQrUnn44MD9z0IPxB1RY5SMpo5W4LWhxAeTDVK7SqACAd9 Ol0LI4qxv76IP5nK8Rpme7 X-Google-Smtp-Source: ABdhPJxbbcxiC7pv6AKukkgRqnx/C9JlUCW130ayKY6GUpNOmDEGE7VxHmt1k7S1K07Qf6rL/fxJ0A== X-Received: by 2002:a17:90a:a60a:: with SMTP id c10mr8349447pjq.117.1594419037224; Fri, 10 Jul 2020 15:10:37 -0700 (PDT) Received: from [10.136.13.65] ([192.19.228.250]) by smtp.gmail.com with ESMTPSA id b22sm6392055pju.26.2020.07.10.15.10.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 10 Jul 2020 15:10:36 -0700 (PDT) Subject: Re: [PATCH 2/4] fs: Remove FIRMWARE_PREALLOC_BUFFER from kernel_read_file() enums To: Matthew Wilcox Cc: Kees Cook , James Morris , Luis Chamberlain , Mimi Zohar , Greg Kroah-Hartman , "Rafael J. Wysocki" , Alexander Viro , Jessica Yu , Dmitry Kasatkin , "Serge E. Hallyn" , Casey Schaufler , "Eric W. Biederman" , Peter Zijlstra , Matthew Garrett , David Howells , Mauro Carvalho Chehab , Randy Dunlap , "Joel Fernandes (Google)" , KP Singh , Dave Olsthoorn , Hans de Goede , Peter Jones , Andrew Morton , Stephen Boyd , Paul Moore , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org References: <20200707081926.3688096-1-keescook@chromium.org> <20200707081926.3688096-3-keescook@chromium.org> <3fdb3c53-7471-14d8-ce6a-251d8b660b8a@broadcom.com> <20200710220411.GR12769@casper.infradead.org> From: Scott Branden Message-ID: <128120ca-7465-e041-7481-4c5d53f639dd@broadcom.com> Date: Fri, 10 Jul 2020 15:10:25 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200710220411.GR12769@casper.infradead.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: On 2020-07-10 3:04 p.m., Matthew Wilcox wrote: > On Fri, Jul 10, 2020 at 02:00:32PM -0700, Scott Branden wrote: >>> @@ -950,8 +951,8 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size, >>> goto out; >>> } >>> - if (id != READING_FIRMWARE_PREALLOC_BUFFER) >>> - *buf = vmalloc(i_size); >>> + if (!*buf) >> The assumption that *buf is always NULL when id != >> READING_FIRMWARE_PREALLOC_BUFFER doesn't appear to be correct. >> I get unhandled page faults due to this change on boot. > Did it give you a stack backtrace? Yes, but there's no requirement that *buf need to be NULL when calling this function. To fix my particular crash I added the following locally: --- a/kernel/module.c +++ b/kernel/module.c @@ -3989,7 +3989,7 @@ SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags)  {      struct load_info info = { };      loff_t size; -    void *hdr; +    void *hdr = NULL;      int err;      err = may_init_module(); >