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,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham 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 73769C433E0 for ; Wed, 13 Jan 2021 17:25:04 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A7B8120739 for ; Wed, 13 Jan 2021 17:25:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A7B8120739 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A62278D0076; Wed, 13 Jan 2021 12:25:02 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id A11C68D006A; Wed, 13 Jan 2021 12:25:02 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 927568D0076; Wed, 13 Jan 2021 12:25:02 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0045.hostedemail.com [216.40.44.45]) by kanga.kvack.org (Postfix) with ESMTP id 7CD0D8D006A for ; Wed, 13 Jan 2021 12:25:02 -0500 (EST) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 3975B180AD82F for ; Wed, 13 Jan 2021 17:25:02 +0000 (UTC) X-FDA: 77701427244.05.jeans34_1a159a82751f Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin05.hostedemail.com (Postfix) with ESMTP id 14DBA18082C87 for ; Wed, 13 Jan 2021 17:25:02 +0000 (UTC) X-HE-Tag: jeans34_1a159a82751f X-Filterd-Recvd-Size: 3711 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf17.hostedemail.com (Postfix) with ESMTP for ; Wed, 13 Jan 2021 17:25:01 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 023E0ACF5; Wed, 13 Jan 2021 17:24:59 +0000 (UTC) Subject: Re: [PATCH 1/2] kasan, mm: fix conflicts with init_on_alloc/free To: Andrey Konovalov , Catalin Marinas , Vincenzo Frascino , Dmitry Vyukov , Alexander Potapenko , Marco Elver Cc: Andrew Morton , Will Deacon , Andrey Ryabinin , Peter Collingbourne , Evgenii Stepanov , Branislav Rankov , Kevin Brodsky , kasan-dev@googlegroups.com, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <7fbac00e4d155cf529517a165a48351dcf3c3156.1610553774.git.andreyknvl@google.com> From: Vlastimil Babka Message-ID: <25aa25d6-080c-ccfa-9367-fc60f46ff10f@suse.cz> Date: Wed, 13 Jan 2021 18:24:58 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <7fbac00e4d155cf529517a165a48351dcf3c3156.1610553774.git.andreyknvl@google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit 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 1/13/21 5:03 PM, Andrey Konovalov wrote: > A few places where SLUB accesses object's data or metadata were missed in > a previous patch. This leads to false positives with hardware tag-based > KASAN when bulk allocations are used with init_on_alloc/free. > > Fix the false-positives by resetting pointer tags during these accesses. > > Link: https://linux-review.googlesource.com/id/I50dd32838a666e173fe06c3c5c766f2c36aae901 > Fixes: aa1ef4d7b3f67 ("kasan, mm: reset tags when accessing metadata") > Reported-by: Dmitry Vyukov > Signed-off-by: Andrey Konovalov Acked-by: Vlastimil Babka > --- > mm/slub.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/mm/slub.c b/mm/slub.c > index dc5b42e700b8..75fb097d990d 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -2791,7 +2791,8 @@ static __always_inline void maybe_wipe_obj_freeptr(struct kmem_cache *s, > void *obj) > { > if (unlikely(slab_want_init_on_free(s)) && obj) > - memset((void *)((char *)obj + s->offset), 0, sizeof(void *)); > + memset((void *)((char *)kasan_reset_tag(obj) + s->offset), > + 0, sizeof(void *)); > } > > /* > @@ -2883,7 +2884,7 @@ static __always_inline void *slab_alloc_node(struct kmem_cache *s, > stat(s, ALLOC_FASTPATH); > } > > - maybe_wipe_obj_freeptr(s, kasan_reset_tag(object)); > + maybe_wipe_obj_freeptr(s, object); And in that case the reset was unnecessary, right. (commit log only mentions adding missing resets). > if (unlikely(slab_want_init_on_alloc(gfpflags, s)) && object) > memset(kasan_reset_tag(object), 0, s->object_size); > @@ -3329,7 +3330,7 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, > int j; > > for (j = 0; j < i; j++) > - memset(p[j], 0, s->object_size); > + memset(kasan_reset_tag(p[j]), 0, s->object_size); > } > > /* memcg and kmem_cache debug support */ >