From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f47.google.com (mail-lf0-f47.google.com [209.85.215.47]) by kanga.kvack.org (Postfix) with ESMTP id 10517828F3 for ; Mon, 11 Jan 2016 07:50:59 -0500 (EST) Received: by mail-lf0-f47.google.com with SMTP id 17so10407979lfz.1 for ; Mon, 11 Jan 2016 04:50:59 -0800 (PST) Received: from relay.parallels.com (relay.parallels.com. [195.214.232.42]) by mx.google.com with ESMTPS id th5si68987388lbb.36.2016.01.11.04.50.57 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 11 Jan 2016 04:50:57 -0800 (PST) From: 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> 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 Sender: owner-linux-mm@kvack.org List-ID: To: Borislav Petkov , Andy Lutomirski , x86@kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" Cc: Brian Gerst , Dave Hansen , Linus Torvalds , Oleg Nesterov , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Ryabinin 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org