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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 8587FC3A5A3 for ; Thu, 29 Aug 2019 18:15:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6039B2339E for ; Thu, 29 Aug 2019 18:15:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567102507; bh=UawKxel9NpXxg9oacRYyoPRRnVT7c7gYBtipihZk+NQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Zl1jCLbhEDtSj9SYYfPv9Y6rgbiFb+NPl/L+naR/WwUYZTh7q5vMI0Ut1lngyACWl kHw38AZNiWDwL/FSlefuiAekC6YCjjEjMDicMx1lCZURi1/bRrE2aWCewsBoJ70yM2 X26DP0B/MqAolnF/kse2VOyGUWmW/jAxxkYSHxZc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729139AbfH2SPF (ORCPT ); Thu, 29 Aug 2019 14:15:05 -0400 Received: from mail.kernel.org ([198.145.29.99]:56632 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729055AbfH2SPB (ORCPT ); Thu, 29 Aug 2019 14:15:01 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1F00F233FF; Thu, 29 Aug 2019 18:14:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567102500; bh=UawKxel9NpXxg9oacRYyoPRRnVT7c7gYBtipihZk+NQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=da25sV5KMmt/x3ExG0jyioeOvL+g07wk0FuGkDfcrsMeRP5nYxiNbEHWsIOo00HLL jPU5cOg2UHILt/HhFulsdc5vvJJVmcVriNRw4ZacV5w+SSEvHv1MU6C1MCitq7cWyA 9E1XDxfN7deEZju3TukEz8+U/cn6rdUolWU7F1Xc= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Kirill A. Shutemov" , "Kirill A . Shutemov" , Borislav Petkov , "H. Peter Anvin" , Ingo Molnar , Thomas Gleixner , x86-ml , Sasha Levin Subject: [PATCH AUTOSEL 5.2 51/76] x86/boot/compressed/64: Fix boot on machines with broken E820 table Date: Thu, 29 Aug 2019 14:12:46 -0400 Message-Id: <20190829181311.7562-51-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190829181311.7562-1-sashal@kernel.org> References: <20190829181311.7562-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Kirill A. Shutemov" [ Upstream commit 0a46fff2f9108c2c44218380a43a736cf4612541 ] BIOS on Samsung 500C Chromebook reports very rudimentary E820 table that consists of 2 entries: BIOS-e820: [mem 0x0000000000000000-0x0000000000000fff] usable BIOS-e820: [mem 0x00000000fffff000-0x00000000ffffffff] reserved It breaks logic in find_trampoline_placement(): bios_start lands on the end of the first 4k page and trampoline start gets placed below 0. Detect underflow and don't touch bios_start for such cases. It makes kernel ignore E820 table on machines that doesn't have two usable pages below BIOS_START_MAX. Fixes: 1b3a62643660 ("x86/boot/compressed/64: Validate trampoline placement against E820") Signed-off-by: Kirill A. Shutemov Signed-off-by: Borislav Petkov Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Thomas Gleixner Cc: x86-ml Link: https://bugzilla.kernel.org/show_bug.cgi?id=203463 Link: https://lkml.kernel.org/r/20190813131654.24378-1-kirill.shutemov@linux.intel.com Signed-off-by: Sasha Levin --- arch/x86/boot/compressed/pgtable_64.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/arch/x86/boot/compressed/pgtable_64.c b/arch/x86/boot/compressed/pgtable_64.c index f8debf7aeb4c1..f0537a1f7fc25 100644 --- a/arch/x86/boot/compressed/pgtable_64.c +++ b/arch/x86/boot/compressed/pgtable_64.c @@ -73,6 +73,8 @@ static unsigned long find_trampoline_placement(void) /* Find the first usable memory region under bios_start. */ for (i = boot_params->e820_entries - 1; i >= 0; i--) { + unsigned long new; + entry = &boot_params->e820_table[i]; /* Skip all entries above bios_start. */ @@ -85,15 +87,20 @@ static unsigned long find_trampoline_placement(void) /* Adjust bios_start to the end of the entry if needed. */ if (bios_start > entry->addr + entry->size) - bios_start = entry->addr + entry->size; + new = entry->addr + entry->size; /* Keep bios_start page-aligned. */ - bios_start = round_down(bios_start, PAGE_SIZE); + new = round_down(new, PAGE_SIZE); /* Skip the entry if it's too small. */ - if (bios_start - TRAMPOLINE_32BIT_SIZE < entry->addr) + if (new - TRAMPOLINE_32BIT_SIZE < entry->addr) continue; + /* Protect against underflow. */ + if (new - TRAMPOLINE_32BIT_SIZE > bios_start) + break; + + bios_start = new; break; } -- 2.20.1