From patchwork Tue Nov 22 11:12:25 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Evgeniy Baskov X-Patchwork-Id: 13052221 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 42772C43217 for ; Tue, 22 Nov 2022 11:18:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233193AbiKVLSc (ORCPT ); Tue, 22 Nov 2022 06:18:32 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33600 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232682AbiKVLRc (ORCPT ); Tue, 22 Nov 2022 06:17:32 -0500 Received: from mail.ispras.ru (mail.ispras.ru [83.149.199.84]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8A488DEE9; Tue, 22 Nov 2022 03:14:46 -0800 (PST) Received: from localhost.localdomain (unknown [83.149.199.65]) by mail.ispras.ru (Postfix) with ESMTPSA id 91753419E9FE; Tue, 22 Nov 2022 11:14:44 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 mail.ispras.ru 91753419E9FE DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ispras.ru; s=default; t=1669115684; bh=hDUzGiUVmLaacOXu/z6JftlYgMxorcNB1P4zYdNcUVA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fGp+oA9iDBAPhlVYXBcZfYbMN02qaqGsTRz7H2BSjs+/7jTtObG+4M1M1MvcrYwyS rYutse9d68YK6zjZDvAzrCSHnlnmMKYENCBqkOjK7G3Nonpj+4/J67ocO4x5QqnaD1 9pQax7kYHukdsFvsRvMvpiQU/uMqsb/hTPSoqBjk= From: Evgeniy Baskov To: Ard Biesheuvel Cc: Evgeniy Baskov , Borislav Petkov , Andy Lutomirski , Dave Hansen , Ingo Molnar , Peter Zijlstra , Thomas Gleixner , Alexey Khoroshilov , Peter Jones , "Limonciello, Mario" , joeyli , lvc-project@linuxtesting.org, x86@kernel.org, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH v3 16/24] x86/boot: Reduce lower limit of physical KASLR Date: Tue, 22 Nov 2022 14:12:25 +0300 Message-Id: <0e6a4c9c7655d3f42f624e1174b223fec5b2b087.1668958803.git.baskov@ispras.ru> X-Mailer: git-send-email 2.37.4 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org Set lower limit of physical KASLR to 64M. Previously is was set to 512M when kernel is loaded higher than that. That prevented physical KASLR from being performed on x86_32, where upper limit is also set to 512M. The limit is pretty arbitrary, and the most important is to set it above the ISA hole, i.e. higher than 16M. It was not that important before, but now kernel is not getting relocated to the lower address when booting via EFI, exposing the KASLR failures. Tested-by: Mario Limonciello Signed-off-by: Evgeniy Baskov --- arch/x86/boot/compressed/kaslr.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c index 7e09d65f7b57..672550686f62 100644 --- a/arch/x86/boot/compressed/kaslr.c +++ b/arch/x86/boot/compressed/kaslr.c @@ -852,10 +852,10 @@ void choose_random_location(unsigned long input, /* * Low end of the randomization range should be the - * smaller of 512M or the initial kernel image + * smaller of 64M or the initial kernel image * location: */ - min_addr = min(*output, 512UL << 20); + min_addr = min(*output, 64UL << 20); /* Make sure minimum is aligned. */ min_addr = ALIGN(min_addr, CONFIG_PHYSICAL_ALIGN);