From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753324AbcEIWBG (ORCPT ); Mon, 9 May 2016 18:01:06 -0400 Received: from mail-vk0-f65.google.com ([209.85.213.65]:34701 "EHLO mail-vk0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751628AbcEIWBE (ORCPT ); Mon, 9 May 2016 18:01:04 -0400 MIME-Version: 1.0 In-Reply-To: <1462825332-10505-2-git-send-email-keescook@chromium.org> References: <1462825332-10505-1-git-send-email-keescook@chromium.org> <1462825332-10505-2-git-send-email-keescook@chromium.org> Date: Mon, 9 May 2016 15:01:02 -0700 X-Google-Sender-Auth: NDq08qneI-7w29WURWx37hsi1ns Message-ID: Subject: Re: [PATCH v7 1/9] x86/KASLR: Initialize mapping_info every time From: Yinghai Lu To: Kees Cook Cc: Ingo Molnar , Borislav Petkov , Baoquan He , Ingo Molnar , "H. Peter Anvin" , Borislav Petkov , Vivek Goyal , Andy Lutomirski , lasse.collin@tukaani.org, Andrew Morton , Dave Young , "kernel-hardening@lists.openwall.com" , LKML Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 9, 2016 at 1:22 PM, Kees Cook wrote: > As it turns out, mapping_info DOES need to be initialized every > time. Without this, page tables were not being corrected updated, which > could cause reboots when a physical address beyond 2G was chosen. > > Signed-off-by: Kees Cook > --- > arch/x86/boot/compressed/pagetable.c | 16 +++++----------- > 1 file changed, 5 insertions(+), 11 deletions(-) > > diff --git a/arch/x86/boot/compressed/pagetable.c b/arch/x86/boot/compressed/pagetable.c > index 3c99051566a9..34b95df14e69 100644 > --- a/arch/x86/boot/compressed/pagetable.c > +++ b/arch/x86/boot/compressed/pagetable.c > @@ -90,23 +90,17 @@ static void prepare_level4(void) > } > > /* > - * Mapping information structure passed to kernel_ident_mapping_init(). > - * Since this never changes, there's no reason to repeatedly fill it > - * in on the stack when calling add_identity_map(). > - */ > -static struct x86_mapping_info mapping_info = { > - .alloc_pgt_page = alloc_pgt_page, > - .context = &pgt_data, > - .pmd_flag = __PAGE_KERNEL_LARGE_EXEC, > -}; > - > -/* > * Adds the specified range to what will become the new identity mappings. > * Once all ranges have been added, the new mapping is activated by calling > * finalize_identity_maps() below. > */ > void add_identity_map(unsigned long start, unsigned long size) > { > + struct x86_mapping_info mapping_info = { > + .alloc_pgt_page = alloc_pgt_page, > + .context = &pgt_data, > + .pmd_flag = __PAGE_KERNEL_LARGE_EXEC, > + }; > unsigned long end = start + size; Still should be assigned once, and should be done in prepare_level4(). --- by may need different name for that ? The exact reason to have assigning in functions. pgt_data address could be changed during kernel relocation. so can not assigned during compiling time. Thanks Yinghai