From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757420AbdJKIbz (ORCPT ); Wed, 11 Oct 2017 04:31:55 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:7560 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932720AbdJKI2O (ORCPT ); Wed, 11 Oct 2017 04:28:14 -0400 From: Abbott Liu To: , , , , , , , , , , , , , , , , , , , , , , CC: , , , , , , , , , , Subject: [PATCH 10/11] Change mapping of kasan_zero_page int readonly Date: Wed, 11 Oct 2017 16:22:26 +0800 Message-ID: <20171011082227.20546-11-liuwenliang@huawei.com> X-Mailer: git-send-email 2.9.0 In-Reply-To: <20171011082227.20546-1-liuwenliang@huawei.com> References: <20171011082227.20546-1-liuwenliang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.67.54.198] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020205.59DDD541.0018,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2014-11-16 11:51:01, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: b50e80c439e1d14b15854e1b7b6bc5ff Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Because the kasan_zero_page(which is used as the shadow region for some memory that KASan doesn't need to track.) won't be writen after kasan_init, so change the mapping of kasan_zero_page into readonly. Cc: Andrey Ryabinin --- arch/arm/mm/kasan_init.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/arm/mm/kasan_init.c b/arch/arm/mm/kasan_init.c index 7cfdc39..c11826a 100644 --- a/arch/arm/mm/kasan_init.c +++ b/arch/arm/mm/kasan_init.c @@ -200,6 +200,7 @@ void __init kasan_init(void) { struct memblock_region *reg; u64 orig_ttbr0; + int i; orig_ttbr0 = cpu_get_ttbr(0); @@ -243,6 +244,17 @@ void __init kasan_init(void) create_mapping((unsigned long)kasan_mem_to_shadow((void *)MODULES_VADDR), (unsigned long)kasan_mem_to_shadow((void *)(PKMAP_BASE+PMD_SIZE)), NUMA_NO_NODE); + + /* + * KAsan may reuse the contents of kasan_zero_pte directly, so we + * should make sure that it maps the zero page read-only. + */ + for (i = 0; i < PTRS_PER_PTE; i++) + set_pte_at(&init_mm, KASAN_SHADOW_START + i*PAGE_SIZE, + &kasan_zero_pte[i], pfn_pte( + virt_to_pfn(kasan_zero_page), + __pgprot(_L_PTE_DEFAULT | L_PTE_DIRTY | L_PTE_XN | L_PTE_RDONLY))); + memset(kasan_zero_page, 0, PAGE_SIZE); cpu_set_ttbr0(orig_ttbr0); flush_cache_all(); local_flush_bp_all(); -- 2.9.0