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=-2.6 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, 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 D7DFEECDE5F for ; Wed, 25 Jul 2018 15:48:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 91D3F204EC for ; Wed, 25 Jul 2018 15:48:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=8bytes.org header.i=@8bytes.org header.b="jWvJ76oN" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 91D3F204EC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=8bytes.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729213AbeGYRAh (ORCPT ); Wed, 25 Jul 2018 13:00:37 -0400 Received: from 8bytes.org ([81.169.241.247]:40220 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728360AbeGYRAh (ORCPT ); Wed, 25 Jul 2018 13:00:37 -0400 Received: by theia.8bytes.org (Postfix, from userid 1000) id D9F372DF; Wed, 25 Jul 2018 17:48:19 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=8bytes.org; s=mail-1; t=1532533699; bh=7uyJQGX9MH9cxdB/eSz9dqZtNfQZQYIzfaEbxYSk570=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jWvJ76oNSjsoIEonhak0wCu79+mD3+lH8iEegZ2evNmKO+cqf2NAIgHNfcKAMaf/a MwEA8Nmk4a36mKs1n/PTDVMNm2lbnbqUzO8yVgmf5QPOFm/saH6ykWhxrPA1/ua4rQ jcfBBfX4noPHzUHxiqVdpkXt3zjYVsmYMFnvcPNkVJbkqpPIDyC98hRITyAH2mvxhX Dz8rmMkMDrQGy2YlBi05whtLt7MmvrCzvXCkNig/FKr5J0XFZ6B8xWjhcAFraBcj9l 9QaqO1QXQT/Ghrq9msDwWKdx4gjaCnXVe+LKKXJ3G2xG+JjaZmiVNAdnEC2ReocCF4 0xZCnx2vRRXpw== From: Joerg Roedel To: Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" Cc: x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Linus Torvalds , Andy Lutomirski , Dave Hansen , Josh Poimboeuf , Juergen Gross , Peter Zijlstra , Borislav Petkov , Jiri Kosina , Boris Ostrovsky , Brian Gerst , David Laight , Denys Vlasenko , Eduardo Valentin , Greg KH , Will Deacon , aliguori@amazon.com, daniel.gruss@iaik.tugraz.at, hughd@google.com, keescook@google.com, Andrea Arcangeli , Waiman Long , Pavel Machek , "David H . Gutteridge" , jroedel@suse.de, Arnaldo Carvalho de Melo , Alexander Shishkin , Jiri Olsa , Namhyung Kim , joro@8bytes.org Subject: [PATCH 3/3] x86/kexec: Allocate 8k PGDs for PTI Date: Wed, 25 Jul 2018 17:48:03 +0200 Message-Id: <1532533683-5988-4-git-send-email-joro@8bytes.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1532533683-5988-1-git-send-email-joro@8bytes.org> References: <1532533683-5988-1-git-send-email-joro@8bytes.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Joerg Roedel Fuzzing the PTI-x86-32 code with trinity showed unhandled kernel paging request oops-messages that looked a lot like silent data corruption. Lot's of debugging and testing lead to the kexec-32bit code, which is still allocating 4k PGDs when PTI is enabled. But since it uses native_set_pud() to build the page-table, it will unevitably call into __pti_set_user_pgtbl(), which writes beyond the allocated 4k page. Use PGD_ALLOCATION_ORDER to allocate PGDs in the kexec code to fix the issue. Signed-off-by: Joerg Roedel --- arch/x86/kernel/machine_kexec_32.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/machine_kexec_32.c b/arch/x86/kernel/machine_kexec_32.c index d1ab07e..5409c28 100644 --- a/arch/x86/kernel/machine_kexec_32.c +++ b/arch/x86/kernel/machine_kexec_32.c @@ -56,7 +56,7 @@ static void load_segments(void) static void machine_kexec_free_page_tables(struct kimage *image) { - free_page((unsigned long)image->arch.pgd); + free_pages((unsigned long)image->arch.pgd, PGD_ALLOCATION_ORDER); image->arch.pgd = NULL; #ifdef CONFIG_X86_PAE free_page((unsigned long)image->arch.pmd0); @@ -72,7 +72,8 @@ static void machine_kexec_free_page_tables(struct kimage *image) static int machine_kexec_alloc_page_tables(struct kimage *image) { - image->arch.pgd = (pgd_t *)get_zeroed_page(GFP_KERNEL); + image->arch.pgd = (pgd_t *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, + PGD_ALLOCATION_ORDER); #ifdef CONFIG_X86_PAE image->arch.pmd0 = (pmd_t *)get_zeroed_page(GFP_KERNEL); image->arch.pmd1 = (pmd_t *)get_zeroed_page(GFP_KERNEL); -- 2.7.4