Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757606AbeAHNCl (ORCPT + 1 other); Mon, 8 Jan 2018 08:02:41 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:44810 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757572AbeAHNCi (ORCPT ); Mon, 8 Jan 2018 08:02:38 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andrey Ryabinin , Borislav Petkov , Andrew Morton , Andy Lutomirski , Andy Lutomirski , Borislav Petkov , Brian Gerst , Dave Hansen , Denys Vlasenko , "H. Peter Anvin" , Linus Torvalds , "Luis R. Rodriguez" , Oleg Nesterov , Peter Zijlstra , Thomas Gleixner , Toshi Kani , linux-mm@kvack.org, Ingo Molnar , Guenter Roeck Subject: [PATCH 4.4 01/22] x86/kasan: Write protect kasan zero shadow Date: Mon, 8 Jan 2018 13:59:28 +0100 Message-Id: <20180108125925.665331563@linuxfoundation.org> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20180108125925.601688333@linuxfoundation.org> References: <20180108125925.601688333@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Andrey Ryabinin commit 063fb3e56f6dd29b2633b678b837e1d904200e6f upstream. After kasan_init() executed, no one is allowed to write to kasan_zero_page, so write protect it. Signed-off-by: Andrey Ryabinin Reviewed-by: Borislav Petkov Cc: Andrew Morton Cc: Andy Lutomirski Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Luis R. Rodriguez Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Toshi Kani Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/1452516679-32040-3-git-send-email-aryabinin@virtuozzo.com Signed-off-by: Ingo Molnar Cc: Guenter Roeck Signed-off-by: Greg Kroah-Hartman --- arch/x86/mm/kasan_init_64.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) --- a/arch/x86/mm/kasan_init_64.c +++ b/arch/x86/mm/kasan_init_64.c @@ -126,10 +126,16 @@ void __init kasan_init(void) /* * kasan_zero_page has been used as early shadow memory, thus it may - * contain some garbage. Now we can clear it, since after the TLB flush - * no one should write to it. + * contain some garbage. Now we can clear and write protect it, since + * after the TLB flush no one should write to it. */ memset(kasan_zero_page, 0, PAGE_SIZE); + for (i = 0; i < PTRS_PER_PTE; i++) { + pte_t pte = __pte(__pa(kasan_zero_page) | __PAGE_KERNEL_RO); + set_pte(&kasan_zero_pte[i], pte); + } + /* Flush TLBs again to be sure that write protection applied. */ + __flush_tlb_all(); init_task.kasan_depth = 0; pr_info("KernelAddressSanitizer initialized\n");