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=-17.4 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_IN_DEF_DKIM_WL 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 02205C4742C for ; Mon, 2 Nov 2020 15:17:19 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 76BEB21D40 for ; Mon, 2 Nov 2020 15:17:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="DkhU/qMV" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 76BEB21D40 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 043F26B0070; Mon, 2 Nov 2020 10:17:18 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id F344C6B0071; Mon, 2 Nov 2020 10:17:17 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E150A6B0072; Mon, 2 Nov 2020 10:17:17 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0160.hostedemail.com [216.40.44.160]) by kanga.kvack.org (Postfix) with ESMTP id 8B2746B0070 for ; Mon, 2 Nov 2020 10:17:17 -0500 (EST) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 1F38B1EE6 for ; Mon, 2 Nov 2020 15:17:17 +0000 (UTC) X-FDA: 77439831714.20.sofa38_1809792272b1 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin20.hostedemail.com (Postfix) with ESMTP id EBC36180C07AF for ; Mon, 2 Nov 2020 15:17:16 +0000 (UTC) X-HE-Tag: sofa38_1809792272b1 X-Filterd-Recvd-Size: 9258 Received: from mail-pf1-f196.google.com (mail-pf1-f196.google.com [209.85.210.196]) by imf29.hostedemail.com (Postfix) with ESMTP for ; Mon, 2 Nov 2020 15:17:16 +0000 (UTC) Received: by mail-pf1-f196.google.com with SMTP id 13so11374563pfy.4 for ; Mon, 02 Nov 2020 07:17:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=3SSjI8L6tAN7wnaresierGkcZcom6o46dDNzyiPHjlU=; b=DkhU/qMVrvN1fx4wAGkNA9axcRMaO84W+G/hRGQCobjjbFdT50hJC+Y0P1+WsLC/fC nQjYHCHoPj9rXVGzQWB7TF3L7FxjLAfh1rLJIGaWPqojCrRG0UyO/MrQueQN3REsMBzk xy1+ZQCYCtioNMDJCLMNTShS0wp/dl83ZmeYPRRQTr9bOuUbhQ7KBGqBzCZmwqZde+3U OjIDIuDW4ct8N6zFiAhT3BmW1YmvSSl3Ned6jfQhv2SiRUlcE8mMSszc2T9KHg5xG3gl OJI2jAfwQkYpHdrke4KFyQMb2LyDzkNTrO/VuDGvlmGcTc0/fyjQFik6WagkeD6Dp+jf DeKw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=3SSjI8L6tAN7wnaresierGkcZcom6o46dDNzyiPHjlU=; b=SR8Pev1k2O6K7skW4C6im/fpChg91mBkMgGQbJTWsiSSPgMWcl6lCUFF1rHHz6H8fc R00KaDmy4Nx0SNLkmW1Ne/CuwFzcptJbuEuwhPhjdZtoYRbQtKHljhVtQ65gO5aAbwKL GybVbTYfx1FJ/qADjfX7inVMqU4P3SSB4IwvXlcEeSpOe13Ics1aWw0rw679wLTB8I0A ePFgg7Rgp3vI3VqPqT4HMaEA8cz2ZYFF+t5Wp2mnQYbAfvXRZkwvnfGdowykGFobM2Wc b3XHXHv350VyReLVFaBoBklvsWr9rdVEJ3NCOVOXJb+UZsaOYrOVR2L6PyUctAIWMfMA pAzQ== X-Gm-Message-State: AOAM533liR7lckL9+851QJYv1To7ZbY2nJlZ5kJ5Ca+0ncxIDKqMd8k/ clsnI+E6ByT11JRWGY4g4iSTPA8TLrQXbgC3DRWeFQ== X-Google-Smtp-Source: ABdhPJyRJC3YZ5USOl/mcJCYzr7fXk7g4cY3TwW4VhXjTLtE65jadiAZBn5mzk3cAxoYI7xitmatRSaV0b0XNSTpUyU= X-Received: by 2002:a63:d456:: with SMTP id i22mr13760189pgj.440.1604330235200; Mon, 02 Nov 2020 07:17:15 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Andrey Konovalov Date: Mon, 2 Nov 2020 16:17:04 +0100 Message-ID: Subject: Re: [PATCH RFC v2 16/21] kasan: optimize poisoning in kmalloc and krealloc To: Dmitry Vyukov Cc: Catalin Marinas , Will Deacon , Vincenzo Frascino , Alexander Potapenko , Marco Elver , Evgenii Stepanov , Kostya Serebryany , Peter Collingbourne , Serban Constantinescu , Andrey Ryabinin , Elena Petrova , Branislav Rankov , Kevin Brodsky , Andrew Morton , kasan-dev , Linux ARM , Linux-MM , LKML Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Oct 28, 2020 at 5:55 PM Dmitry Vyukov wrote: > > On Thu, Oct 22, 2020 at 3:20 PM Andrey Konovalov wrote: > > > > Since kasan_kmalloc() always follows kasan_slab_alloc(), there's no need > > to reunpoison the object data, only to poison the redzone. > > > > This requires changing kasan annotation for early SLUB cache to > > kasan_slab_alloc(). Otherwise kasan_kmalloc() doesn't untag the object. > > This doesn't do any functional changes, as kmem_cache_node->object_size > > is equal to sizeof(struct kmem_cache_node). > > > > Similarly for kasan_krealloc(), as it's called after ksize(), which > > already unpoisoned the object, there's no need to do it again. > > Have you considered doing this the other way around: make krealloc > call __ksize and unpoison in kasan_krealloc? > This has the advantage of more precise poisoning as ksize will > unpoison the whole underlying object. > > But then maybe we will need to move first checks in ksize into __ksize > as we may need them in krealloc as well. This might be a good idea. I won't implement this for the next version, but will look into this after that. Thanks! > > > > > > > Signed-off-by: Andrey Konovalov > > Link: https://linux-review.googlesource.com/id/I4083d3b55605f70fef79bca9b90843c4390296f2 > > --- > > mm/kasan/common.c | 31 +++++++++++++++++++++---------- > > mm/slub.c | 3 +-- > > 2 files changed, 22 insertions(+), 12 deletions(-) > > > > diff --git a/mm/kasan/common.c b/mm/kasan/common.c > > index c5ec60e1a4d2..a581937c2a44 100644 > > --- a/mm/kasan/common.c > > +++ b/mm/kasan/common.c > > @@ -360,8 +360,14 @@ static void *____kasan_kmalloc(struct kmem_cache *cache, const void *object, > > if (IS_ENABLED(CONFIG_KASAN_SW_TAGS) || IS_ENABLED(CONFIG_KASAN_HW_TAGS)) > > tag = assign_tag(cache, object, false, keep_tag); > > > > - /* Tag is ignored in set_tag without CONFIG_KASAN_SW/HW_TAGS */ > > - kasan_unpoison_memory(set_tag(object, tag), size); > > + /* > > + * Don't unpoison the object when keeping the tag. Tag is kept for: > > + * 1. krealloc(), and then the memory has already been unpoisoned via ksize(); > > + * 2. kmalloc(), and then the memory has already been unpoisoned by kasan_kmalloc(). > > + * Tag is ignored in set_tag() without CONFIG_KASAN_SW/HW_TAGS. > > + */ > > + if (!keep_tag) > > + kasan_unpoison_memory(set_tag(object, tag), size); > > kasan_poison_memory((void *)redzone_start, redzone_end - redzone_start, > > KASAN_KMALLOC_REDZONE); > > > > @@ -384,10 +390,9 @@ void * __must_check __kasan_kmalloc(struct kmem_cache *cache, const void *object > > } > > EXPORT_SYMBOL(__kasan_kmalloc); > > > > -void * __must_check __kasan_kmalloc_large(const void *ptr, size_t size, > > - gfp_t flags) > > +static void * __must_check ____kasan_kmalloc_large(struct page *page, const void *ptr, > > + size_t size, gfp_t flags, bool realloc) > > { > > - struct page *page; > > unsigned long redzone_start; > > unsigned long redzone_end; > > > > @@ -397,18 +402,24 @@ void * __must_check __kasan_kmalloc_large(const void *ptr, size_t size, > > if (unlikely(ptr == NULL)) > > return NULL; > > > > - page = virt_to_page(ptr); > > - redzone_start = round_up((unsigned long)(ptr + size), > > - KASAN_GRANULE_SIZE); > > + redzone_start = round_up((unsigned long)(ptr + size), KASAN_GRANULE_SIZE); > > redzone_end = (unsigned long)ptr + page_size(page); > > > > - kasan_unpoison_memory(ptr, size); > > + /* ksize() in __do_krealloc() already unpoisoned the memory. */ > > + if (!realloc) > > + kasan_unpoison_memory(ptr, size); > > kasan_poison_memory((void *)redzone_start, redzone_end - redzone_start, > > KASAN_PAGE_REDZONE); > > > > return (void *)ptr; > > } > > > > +void * __must_check __kasan_kmalloc_large(const void *ptr, size_t size, > > + gfp_t flags) > > +{ > > + return ____kasan_kmalloc_large(virt_to_page(ptr), ptr, size, flags, false); > > +} > > + > > void * __must_check __kasan_krealloc(const void *object, size_t size, gfp_t flags) > > { > > struct page *page; > > @@ -419,7 +430,7 @@ void * __must_check __kasan_krealloc(const void *object, size_t size, gfp_t flag > > page = virt_to_head_page(object); > > > > if (unlikely(!PageSlab(page))) > > - return __kasan_kmalloc_large(object, size, flags); > > + return ____kasan_kmalloc_large(page, object, size, flags, true); > > else > > return ____kasan_kmalloc(page->slab_cache, object, size, > > flags, true); > > diff --git a/mm/slub.c b/mm/slub.c > > index 1d3f2355df3b..afb035b0bf2d 100644 > > --- a/mm/slub.c > > +++ b/mm/slub.c > > @@ -3535,8 +3535,7 @@ static void early_kmem_cache_node_alloc(int node) > > init_object(kmem_cache_node, n, SLUB_RED_ACTIVE); > > init_tracking(kmem_cache_node, n); > > #endif > > - n = kasan_kmalloc(kmem_cache_node, n, sizeof(struct kmem_cache_node), > > - GFP_KERNEL); > > + n = kasan_slab_alloc(kmem_cache_node, n, GFP_KERNEL); > > page->freelist = get_freepointer(kmem_cache_node, n); > > page->inuse = 1; > > page->frozen = 0; > > -- > > 2.29.0.rc1.297.gfa9743e501-goog > >