From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 24F0DC433DB for ; Fri, 19 Mar 2021 17:38:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0033B61925 for ; Fri, 19 Mar 2021 17:38:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230096AbhCSRiI (ORCPT ); Fri, 19 Mar 2021 13:38:08 -0400 Received: from mail.kernel.org ([198.145.29.99]:43048 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230317AbhCSRiF (ORCPT ); Fri, 19 Mar 2021 13:38:05 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 5557B6197A; Fri, 19 Mar 2021 17:38:01 +0000 (UTC) Date: Fri, 19 Mar 2021 17:37:58 +0000 From: Catalin Marinas To: Lecopzer Chen Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, kasan-dev@googlegroups.com, linux-arm-kernel@lists.infradead.org, will@kernel.org, dan.j.williams@intel.com, aryabinin@virtuozzo.com, glider@google.com, dvyukov@google.com, akpm@linux-foundation.org, linux-mediatek@lists.infradead.org, yj.chiang@mediatek.com, ardb@kernel.org, andreyknvl@google.com, broonie@kernel.org, linux@roeck-us.net, rppt@kernel.org, tyhicks@linux.microsoft.com, robin.murphy@arm.com, vincenzo.frascino@arm.com, gustavoars@kernel.org, lecopzer@gmail.com Subject: Re: [PATCH v3 1/5] arm64: kasan: don't populate vmalloc area for CONFIG_KASAN_VMALLOC Message-ID: <20210319173758.GC6832@arm.com> References: <20210206083552.24394-1-lecopzer.chen@mediatek.com> <20210206083552.24394-2-lecopzer.chen@mediatek.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210206083552.24394-2-lecopzer.chen@mediatek.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Feb 06, 2021 at 04:35:48PM +0800, Lecopzer Chen wrote: > Linux support KAsan for VMALLOC since commit 3c5c3cfb9ef4da9 > ("kasan: support backing vmalloc space with real shadow memory") > > Like how the MODULES_VADDR does now, just not to early populate > the VMALLOC_START between VMALLOC_END. > > Before: > > MODULE_VADDR: no mapping, no zoreo shadow at init > VMALLOC_VADDR: backed with zero shadow at init > > After: > > MODULE_VADDR: no mapping, no zoreo shadow at init > VMALLOC_VADDR: no mapping, no zoreo shadow at init s/zoreo/zero/ > Thus the mapping will get allocated on demand by the core function > of KASAN_VMALLOC. > > ----------- vmalloc_shadow_start > | | > | | > | | <= non-mapping > | | > | | > |-----------| > |///////////|<- kimage shadow with page table mapping. > |-----------| > | | > | | <= non-mapping > | | > ------------- vmalloc_shadow_end > |00000000000| > |00000000000| <= Zero shadow > |00000000000| > ------------- KASAN_SHADOW_END > > Signed-off-by: Lecopzer Chen > --- > arch/arm64/mm/kasan_init.c | 18 +++++++++++++----- > 1 file changed, 13 insertions(+), 5 deletions(-) > > diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c > index d8e66c78440e..20d06008785f 100644 > --- a/arch/arm64/mm/kasan_init.c > +++ b/arch/arm64/mm/kasan_init.c > @@ -214,6 +214,7 @@ static void __init kasan_init_shadow(void) > { > u64 kimg_shadow_start, kimg_shadow_end; > u64 mod_shadow_start, mod_shadow_end; > + u64 vmalloc_shadow_end; > phys_addr_t pa_start, pa_end; > u64 i; > > @@ -223,6 +224,8 @@ static void __init kasan_init_shadow(void) > mod_shadow_start = (u64)kasan_mem_to_shadow((void *)MODULES_VADDR); > mod_shadow_end = (u64)kasan_mem_to_shadow((void *)MODULES_END); > > + vmalloc_shadow_end = (u64)kasan_mem_to_shadow((void *)VMALLOC_END); > + > /* > * We are going to perform proper setup of shadow memory. > * At first we should unmap early shadow (clear_pgds() call below). > @@ -241,12 +244,17 @@ static void __init kasan_init_shadow(void) > > kasan_populate_early_shadow(kasan_mem_to_shadow((void *)PAGE_END), > (void *)mod_shadow_start); > - kasan_populate_early_shadow((void *)kimg_shadow_end, > - (void *)KASAN_SHADOW_END); > > - if (kimg_shadow_start > mod_shadow_end) > - kasan_populate_early_shadow((void *)mod_shadow_end, > - (void *)kimg_shadow_start); Not something introduced by this patch but what happens if this condition is false? It means that kimg_shadow_end < mod_shadow_start and the above kasan_populate_early_shadow(PAGE_END, mod_shadow_start) overlaps with the earlier kasan_map_populate(kimg_shadow_start, kimg_shadow_end). > + if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) > + kasan_populate_early_shadow((void *)vmalloc_shadow_end, > + (void *)KASAN_SHADOW_END); > + else { > + kasan_populate_early_shadow((void *)kimg_shadow_end, > + (void *)KASAN_SHADOW_END); > + if (kimg_shadow_start > mod_shadow_end) > + kasan_populate_early_shadow((void *)mod_shadow_end, > + (void *)kimg_shadow_start); > + } > > for_each_mem_range(i, &pa_start, &pa_end) { > void *start = (void *)__phys_to_virt(pa_start); > -- > 2.25.1 > -- Catalin