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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7CB21C43334 for ; Thu, 16 Jun 2022 08:31:56 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id EDF856B0072; Thu, 16 Jun 2022 04:31:55 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E8F706B0073; Thu, 16 Jun 2022 04:31:55 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D7E486B0074; Thu, 16 Jun 2022 04:31:55 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id C94386B0072 for ; Thu, 16 Jun 2022 04:31:55 -0400 (EDT) Received: from smtpin25.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay13.hostedemail.com (Postfix) with ESMTP id 54F4861449 for ; Thu, 16 Jun 2022 08:31:55 +0000 (UTC) X-FDA: 79583430990.25.3A3EE33 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf18.hostedemail.com (Postfix) with ESMTP id C58A51C007F for ; Thu, 16 Jun 2022 08:31:54 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 2402112FC; Thu, 16 Jun 2022 01:31:54 -0700 (PDT) Received: from [10.57.69.164] (unknown [10.57.69.164]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 312093F7F5; Thu, 16 Jun 2022 01:31:51 -0700 (PDT) Message-ID: <8982344a-c726-934c-70fc-011b8b83bdd2@arm.com> Date: Thu, 16 Jun 2022 09:31:50 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH v2 1/4] mm: kasan: Ensure the tags are visible before the tag in page->flags Content-Language: en-US To: Catalin Marinas , Andrey Ryabinin , Andrey Konovalov Cc: Will Deacon , Peter Collingbourne , kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org References: <20220610152141.2148929-1-catalin.marinas@arm.com> <20220610152141.2148929-2-catalin.marinas@arm.com> From: Vincenzo Frascino In-Reply-To: <20220610152141.2148929-2-catalin.marinas@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1655368314; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=IqZ+hZyAEiz+E8OGzxpfXdnI7felGnGoOrHidH9d8qQ=; b=z+218VcfPi0yluT9zemt9YIiSek0wsExUHdj4jRuUPswe6LMPMkO7Z8ntK07fn3RkQ+nEO zfgNdzvAZailhGXz2rku1lM4iUmiqMIXDggkKdN78Pb8r2zx8oqwNMEBzWBypbcEdn9HLr dsBBHFk9Ecod1ogMcR1BrIsnzjKp/tY= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1655368314; a=rsa-sha256; cv=none; b=4vcdzBAMUJwoMtSJdifEJcSAmdM8iHMx1xXcj2QJt2JLeTp8BqicvskKoqSTC11Mdp1dk+ r24A1c2qV744no4Mxahcc1/4FEFBPESDyzs9fJWkPcJEWbSQfR+zEVEm2m31XGSVzWWQ2g iFON5Ut2TQhSg73FrClWs/TDWPpDVz0= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf18.hostedemail.com: domain of vincenzo.frascino@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=vincenzo.frascino@arm.com Authentication-Results: imf18.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf18.hostedemail.com: domain of vincenzo.frascino@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=vincenzo.frascino@arm.com X-Rspamd-Server: rspam12 X-Rspam-User: X-Stat-Signature: emahj7r1wba3nmyduh4cebm1wfn744uc X-Rspamd-Queue-Id: C58A51C007F X-HE-Tag: 1655368314-706400 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 6/10/22 16:21, Catalin Marinas wrote: > __kasan_unpoison_pages() colours the memory with a random tag and stores > it in page->flags in order to re-create the tagged pointer via > page_to_virt() later. When the tag from the page->flags is read, ensure > that the in-memory tags are already visible by re-ordering the > page_kasan_tag_set() after kasan_unpoison(). The former already has > barriers in place through try_cmpxchg(). On the reader side, the order > is ensured by the address dependency between page->flags and the memory > access. > > Signed-off-by: Catalin Marinas > Reviewed-by: Andrey Konovalov > Cc: Andrey Ryabinin > Cc: Vincenzo Frascino Reviewed-by: Vincenzo Frascino > --- > mm/kasan/common.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/kasan/common.c b/mm/kasan/common.c > index c40c0e7b3b5f..78be2beb7453 100644 > --- a/mm/kasan/common.c > +++ b/mm/kasan/common.c > @@ -108,9 +108,10 @@ void __kasan_unpoison_pages(struct page *page, unsigned int order, bool init) > return; > > tag = kasan_random_tag(); > + kasan_unpoison(set_tag(page_address(page), tag), > + PAGE_SIZE << order, init); > for (i = 0; i < (1 << order); i++) > page_kasan_tag_set(page + i, tag); > - kasan_unpoison(page_address(page), PAGE_SIZE << order, init); > } > > void __kasan_poison_pages(struct page *page, unsigned int order, bool init) -- Regards, Vincenzo