From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932774AbcAKMvB (ORCPT ); Mon, 11 Jan 2016 07:51:01 -0500 Received: from relay.parallels.com ([195.214.232.42]:55180 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932732AbcAKMu6 (ORCPT ); Mon, 11 Jan 2016 07:50:58 -0500 From: Andrey Ryabinin To: Borislav Petkov , Andy Lutomirski , , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" CC: Brian Gerst , Dave Hansen , Linus Torvalds , Oleg Nesterov , , , Andrey Ryabinin Subject: [PATCH 2/2] x86/kasan: write protect kasan zero shadow Date: Mon, 11 Jan 2016 15:51:19 +0300 Message-ID: <1452516679-32040-3-git-send-email-aryabinin@virtuozzo.com> X-Mailer: git-send-email 2.4.10 In-Reply-To: <1452516679-32040-1-git-send-email-aryabinin@virtuozzo.com> References: <20160110185916.GD22896@pd.tnic> <1452516679-32040-1-git-send-email-aryabinin@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain X-ClientProxiedBy: US-EXCH.sw.swsoft.com (10.255.249.47) To MSK-EXCH1.sw.swsoft.com (10.67.48.55) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org After kasan_init() executed, no one is allowed to write to kasan_zero_page, so write protect it. Signed-off-by: Andrey Ryabinin --- arch/x86/mm/kasan_init_64.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c index 303e470..1b1110f 100644 --- a/arch/x86/mm/kasan_init_64.c +++ b/arch/x86/mm/kasan_init_64.c @@ -125,10 +125,16 @@ 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"); -- 2.4.10