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=-10.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 8D52AC433F8 for ; Mon, 27 Jul 2020 14:12:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6A20B208E4 for ; Mon, 27 Jul 2020 14:12:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595859151; bh=dc5GIlP5hZ2l58dr+lnG1k9qkoosoB/+ERd84z3QCqo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=b3D9d93tnWkPoLh11IV05uNvBbbLAarcaoRP+ehzjqgxTMTqjgndd+67mI2MTaLUg MmYDo0ZtZ9wbz3UfT/xlhilbfnywBRDc0ScUbgrkOFkjGK8QWWjLM5DIarflXU6zKI Tnee8fsLpvD3ryOkml8YJ/o8zwiHKI9HE9vACTj8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730206AbgG0OMa (ORCPT ); Mon, 27 Jul 2020 10:12:30 -0400 Received: from mail.kernel.org ([198.145.29.99]:36560 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730189AbgG0OMU (ORCPT ); Mon, 27 Jul 2020 10:12:20 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D2F6A20838; Mon, 27 Jul 2020 14:12:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595859140; bh=dc5GIlP5hZ2l58dr+lnG1k9qkoosoB/+ERd84z3QCqo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=b6mciHwcRd9ypKEBZMSPBA0aQO/6t+yYCX+LXaCpMrMOYmq1IPdtQVJAvk/V1cE5x x3aybnaAHR+XrXkcn7NZfGTCqHkWm+u4iziPYOqdOht8Ds7sdHcjSYsKDZIM1sfU74 b3h6C6xR8dF/wGjp3YKKCJ005TBcAaZ/3kXEShJs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Joerg Roedel , Thomas Gleixner , Kees Cook Subject: [PATCH 4.19 81/86] x86, vmlinux.lds: Page-align end of ..page_aligned sections Date: Mon, 27 Jul 2020 16:04:55 +0200 Message-Id: <20200727134918.465504233@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200727134914.312934924@linuxfoundation.org> References: <20200727134914.312934924@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Joerg Roedel commit de2b41be8fcccb2f5b6c480d35df590476344201 upstream. On x86-32 the idt_table with 256 entries needs only 2048 bytes. It is page-aligned, but the end of the .bss..page_aligned section is not guaranteed to be page-aligned. As a result, objects from other .bss sections may end up on the same 4k page as the idt_table, and will accidentially get mapped read-only during boot, causing unexpected page-faults when the kernel writes to them. This could be worked around by making the objects in the page aligned sections page sized, but that's wrong. Explicit sections which store only page aligned objects have an implicit guarantee that the object is alone in the page in which it is placed. That works for all objects except the last one. That's inconsistent. Enforcing page sized objects for these sections would wreckage memory sanitizers, because the object becomes artificially larger than it should be and out of bound access becomes legit. Align the end of the .bss..page_aligned and .data..page_aligned section on page-size so all objects places in these sections are guaranteed to have their own page. [ tglx: Amended changelog ] Signed-off-by: Joerg Roedel Signed-off-by: Thomas Gleixner Reviewed-by: Kees Cook Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20200721093448.10417-1-joro@8bytes.org Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/vmlinux.lds.S | 1 + include/asm-generic/vmlinux.lds.h | 5 ++++- 2 files changed, 5 insertions(+), 1 deletion(-) --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -372,6 +372,7 @@ SECTIONS .bss : AT(ADDR(.bss) - LOAD_OFFSET) { __bss_start = .; *(.bss..page_aligned) + . = ALIGN(PAGE_SIZE); *(BSS_MAIN) BSS_DECRYPTED . = ALIGN(PAGE_SIZE); --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -279,7 +279,8 @@ #define PAGE_ALIGNED_DATA(page_align) \ . = ALIGN(page_align); \ - *(.data..page_aligned) + *(.data..page_aligned) \ + . = ALIGN(page_align); #define READ_MOSTLY_DATA(align) \ . = ALIGN(align); \ @@ -650,7 +651,9 @@ . = ALIGN(bss_align); \ .bss : AT(ADDR(.bss) - LOAD_OFFSET) { \ BSS_FIRST_SECTIONS \ + . = ALIGN(PAGE_SIZE); \ *(.bss..page_aligned) \ + . = ALIGN(PAGE_SIZE); \ *(.dynbss) \ *(BSS_MAIN) \ *(COMMON) \