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=-13.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 13CEAC433EB for ; Mon, 27 Jul 2020 23:08:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EC77A20729 for ; Mon, 27 Jul 2020 23:08:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727862AbgG0XIW (ORCPT ); Mon, 27 Jul 2020 19:08:22 -0400 Received: from mail-qk1-f193.google.com ([209.85.222.193]:40615 "EHLO mail-qk1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726967AbgG0XIK (ORCPT ); Mon, 27 Jul 2020 19:08:10 -0400 Received: by mail-qk1-f193.google.com with SMTP id h7so16981810qkk.7 for ; Mon, 27 Jul 2020 16:08:09 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=VRzoFnv3X6rZZ58A9nfh58By1q+3T1zxEck+xIJrMo0=; b=rI3362hRbHQkdRqx6WPDswx/Q3y6X16JrG1UEoZOQo+Ww2if6chHlyfi8Tt+mTuwrX zTS+Rty30tUhcB6BNoH3daNJyURa/XEdcl7PJvPUe2au2Sje6wQkAKmmQuhfsAQ0+n5U MDOh9R5BJsoRaH+c3Z5Dfekj+p2CNYFh7QnStJk7xsyO0tLcyrKsGac1bgKEq5lDb/mI e7rjdDaQOlxwnxHGwTwwxbQI2RQeVXrv/tLYYSTC8d4+H5ghwpdYIUW/3Gur5jMFsZBp BNtsGDlWoTmYmcfU+cST1mTraqB0eb0GvvxKY4ZbJZF+lG7qvMRQrk7Uo2/bJ4lr7UuU WDuA== X-Gm-Message-State: AOAM530TxJleXR7UFMkHf0nCEF2yp+kzdfTfgx0NDyuympn36AaZw5Sd zh09lKMWmb6SJtLbaeypKz8= X-Google-Smtp-Source: ABdhPJyX0ca2NrSgYn5enJuUMbgOdp/UNdCrYLcXYa9StkNntYi8S0u31sYJgO5fSrnIRnsgzi31EA== X-Received: by 2002:a05:620a:2481:: with SMTP id i1mr5485957qkn.139.1595891289482; Mon, 27 Jul 2020 16:08:09 -0700 (PDT) Received: from rani.riverdale.lan ([2001:470:1f07:5f3::b55f]) by smtp.gmail.com with ESMTPSA id j61sm8216984qtd.52.2020.07.27.16.08.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Jul 2020 16:08:08 -0700 (PDT) From: Arvind Sankar To: Kees Cook , x86@kernel.org Cc: linux-kernel@vger.kernel.org Subject: [PATCH v2 7/8] x86/kaslr: Clean up slot handling Date: Mon, 27 Jul 2020 19:08:00 -0400 Message-Id: <20200727230801.3468620-8-nivedita@alum.mit.edu> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200727215047.3341098-1-nivedita@alum.mit.edu> References: <20200727215047.3341098-1-nivedita@alum.mit.edu> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The number of slots and slot areas can be unsigned int, since on 64-bit, the maximum amount of memory is 2^52, the minimum alignment is 2^21, so the slot number cannot be greater than 2^31. The slot areas are limited by MAX_SLOT_AREA, currently 100. Replace the type used for slot number, which is currently a mix of int and unsigned long, with unsigned int consistently. Drop unnecessary check that number of slots is not zero in store_slot_info, it's guaranteed to be at least 1 by the calculation. Drop unnecessary alignment of image_size to CONFIG_PHYSICAL_ALIGN in find_random_virt_addr, it cannot change the result: the largest valid slot is the largest n that satisfies minimum + n * CONFIG_PHYSICAL_ALIGN + image_size <= KERNEL_IMAGE_SIZE (since minimum is already aligned) and so n is equal to (KERNEL_IMAGE_SIZE - minimum - image_size) / CONFIG_PHYSICAL_ALIGN even if image_size is not aligned to CONFIG_PHYSICAL_ALIGN. Signed-off-by: Arvind Sankar --- arch/x86/boot/compressed/kaslr.c | 36 ++++++++++++-------------------- 1 file changed, 13 insertions(+), 23 deletions(-) diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c index 91c5f9771f42..eca2acc65e2a 100644 --- a/arch/x86/boot/compressed/kaslr.c +++ b/arch/x86/boot/compressed/kaslr.c @@ -511,16 +511,14 @@ static bool mem_avoid_overlap(struct mem_vector *img, struct slot_area { unsigned long addr; - int num; + unsigned int num; }; #define MAX_SLOT_AREA 100 static struct slot_area slot_areas[MAX_SLOT_AREA]; - -static unsigned long slot_max; - -static unsigned long slot_area_index; +static unsigned int slot_area_index; +static unsigned int slot_max; static void store_slot_info(struct mem_vector *region, unsigned long image_size) { @@ -530,13 +528,10 @@ static void store_slot_info(struct mem_vector *region, unsigned long image_size) return; slot_area.addr = region->start; - slot_area.num = (region->size - image_size) / - CONFIG_PHYSICAL_ALIGN + 1; + slot_area.num = 1 + (region->size - image_size) / CONFIG_PHYSICAL_ALIGN; - if (slot_area.num > 0) { - slot_areas[slot_area_index++] = slot_area; - slot_max += slot_area.num; - } + slot_areas[slot_area_index++] = slot_area; + slot_max += slot_area.num; } /* @@ -589,8 +584,7 @@ process_gb_huge_pages(struct mem_vector *region, unsigned long image_size) static unsigned long slots_fetch_random(void) { - unsigned long slot; - int i; + unsigned int slot, i; /* Handle case of no slots stored. */ if (slot_max == 0) @@ -603,7 +597,7 @@ static unsigned long slots_fetch_random(void) slot -= slot_areas[i].num; continue; } - return slot_areas[i].addr + slot * CONFIG_PHYSICAL_ALIGN; + return slot_areas[i].addr + (unsigned long)slot * CONFIG_PHYSICAL_ALIGN; } if (i == slot_area_index) @@ -819,28 +813,24 @@ static unsigned long find_random_phys_addr(unsigned long minimum, return 0; } - if (process_efi_entries(minimum, image_size)) - return slots_fetch_random(); + if (!process_efi_entries(minimum, image_size)) + process_e820_entries(minimum, image_size); - process_e820_entries(minimum, image_size); return slots_fetch_random(); } static unsigned long find_random_virt_addr(unsigned long minimum, unsigned long image_size) { - unsigned long slots, random_addr; - - /* Align image_size for easy slot calculations. */ - image_size = ALIGN(image_size, CONFIG_PHYSICAL_ALIGN); + unsigned int slots; + unsigned long random_addr; /* * There are how many CONFIG_PHYSICAL_ALIGN-sized slots * that can hold image_size within the range of minimum to * KERNEL_IMAGE_SIZE? */ - slots = (KERNEL_IMAGE_SIZE - minimum - image_size) / - CONFIG_PHYSICAL_ALIGN + 1; + slots = 1 + (KERNEL_IMAGE_SIZE - minimum - image_size) / CONFIG_PHYSICAL_ALIGN; random_addr = kaslr_get_random_long("Virtual") % slots; -- 2.26.2