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=-5.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 371F2C17443 for ; Mon, 11 Nov 2019 08:25:14 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0CC3820856 for ; Mon, 11 Nov 2019 08:25:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Q/GfOsLA" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0CC3820856 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=virtuozzo.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:To:Subject:Reply-To:Content-ID:Content-Description :Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=nSs54oqiCWJOXNrJAHfGp2dkTtW6SkN2rpU/Hvkthso=; b=Q/GfOsLAXoEMTF ljt04O74R0GgL2IE/mqcy4WbiKUypolSHzG2QYGJr0+9jte1mbAhWWMQpeh/pdieIM51t+ZC51Bs6 QRFDxsVBivjUd5deKlrobVNOPJ9Rs61nITxPHGqP4Ia/Bs413hNcBtxAWDATXHjHvOsta076pm25d 3B6wbiYDbpeGdyvuh7A/g1QLEeqEmub93A7bor6sPf7VQjlUTOMTKoVBqVsfGglnoQy79C2NyAj0f Q/yMeOs1NUE3aAiuVIDZDVH1rbueBGz4iCQNK7Fj9Db4fOOQ1RviBiYezkkw26HPU7HdsW4osSM4g XS+Lv5mZXB0UHCRgrBaA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iU50a-00040x-7M; Mon, 11 Nov 2019 08:25:12 +0000 Received: from relay.sw.ru ([185.231.240.75]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1iU50W-0002pR-K1 for linux-arm-kernel@lists.infradead.org; Mon, 11 Nov 2019 08:25:10 +0000 Received: from [172.16.25.5] by relay.sw.ru with esmtp (Exim 4.92.3) (envelope-from ) id 1iU50L-00018h-TL; Mon, 11 Nov 2019 11:24:58 +0300 Subject: Re: [PATCH v3 1/2] kasan: detect negative size in memory operation function To: Dmitry Vyukov References: <20191104020519.27988-1-walter-zh.wu@mediatek.com> <34bf9c08-d2f2-a6c6-1dbe-29b1456d8284@virtuozzo.com> From: Andrey Ryabinin Message-ID: <20df03c5-e733-98b0-84e9-8d52ddce5c98@virtuozzo.com> Date: Mon, 11 Nov 2019 11:24:36 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191111_002508_661306_E034D0CC X-CRM114-Status: GOOD ( 15.59 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Walter Wu , wsd_upstream , LKML , kasan-dev , Linux-MM , Alexander Potapenko , Matthias Brugger , Linux ARM Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 11/11/19 10:57 AM, Dmitry Vyukov wrote: > On Fri, Nov 8, 2019 at 11:32 PM Andrey Ryabinin wrote: >>> diff --git a/mm/kasan/generic_report.c b/mm/kasan/generic_report.c >>> index 36c645939bc9..52a92c7db697 100644 >>> --- a/mm/kasan/generic_report.c >>> +++ b/mm/kasan/generic_report.c >>> @@ -107,6 +107,24 @@ static const char *get_wild_bug_type(struct kasan_access_info *info) >>> >>> const char *get_bug_type(struct kasan_access_info *info) >>> { >>> + /* >>> + * If access_size is negative numbers, then it has three reasons >>> + * to be defined as heap-out-of-bounds bug type. >>> + * 1) Casting negative numbers to size_t would indeed turn up as >>> + * a large size_t and its value will be larger than ULONG_MAX/2, >>> + * so that this can qualify as out-of-bounds. >>> + * 2) If KASAN has new bug type and user-space passes negative size, >>> + * then there are duplicate reports. So don't produce new bug type >>> + * in order to prevent duplicate reports by some systems >>> + * (e.g. syzbot) to report the same bug twice. >>> + * 3) When size is negative numbers, it may be passed from user-space. >>> + * So we always print heap-out-of-bounds in order to prevent that >>> + * kernel-space and user-space have the same bug but have duplicate >>> + * reports. >>> + */ >> >> Completely fail to understand 2) and 3). 2) talks something about *NOT* producing new bug >> type, but at the same time you code actually does that. >> 3) says something about user-space which have nothing to do with kasan. > > The idea was to use one of the existing bug titles so that syzbot does > not produce 2 versions for OOBs where size is user-controlled. We > don't know if it's overflow from heap, global or stack, but heap is > the most common bug, so saying heap overflow will reduce chances of > producing duplicates the most. > But for all of this to work we do need to use one of the existing bug titles. The "heap-out-of-bounds" is not one of the existing bug titles. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel