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 C8FA3FA3740 for ; Thu, 27 Oct 2022 19:13:24 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5ED916B0071; Thu, 27 Oct 2022 15:13:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 59D2B6B0073; Thu, 27 Oct 2022 15:13:24 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 464EE6B0074; Thu, 27 Oct 2022 15:13:24 -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 336076B0071 for ; Thu, 27 Oct 2022 15:13:24 -0400 (EDT) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id E315940FCC for ; Thu, 27 Oct 2022 19:13:23 +0000 (UTC) X-FDA: 80067677886.06.6E567A4 Received: from mail-pf1-f181.google.com (mail-pf1-f181.google.com [209.85.210.181]) by imf14.hostedemail.com (Postfix) with ESMTP id 6BEF3100005 for ; Thu, 27 Oct 2022 19:13:23 +0000 (UTC) Received: by mail-pf1-f181.google.com with SMTP id m6so2630678pfb.0 for ; Thu, 27 Oct 2022 12:13:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=KRy9sqvf0ZM2bZpgrnftqxmIbppdN+rJl6H1sXbtcEA=; b=ePBvbYsqqxinV1869tyLVSPuexY7f5oFCO4bFBrZ0zRyJ8fAIYv6HyDImZpOI7sDK4 wV01b3ApWa7HxYPZmSq7Y80QJ8waTqfMmGkATXW/AodfcPzYcSL2X9iXgY+1T73b5Ysl 7tELmVPx85ac64Og2sYczqg5VmOjiPDZGHsIc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=KRy9sqvf0ZM2bZpgrnftqxmIbppdN+rJl6H1sXbtcEA=; b=PMUDnWVhjTEi/JEjeZa6Sk0cH1ahgtp/U/WLJwp7iPOMSkN/EDwTl66a96T7kO2vrm 6B2l/lBc2DQTMyR84X5vZ481YTOcfN+iJidBNiWPD8T8cRVpyAunzn+RrCBhc+SwpvLg mZT2qWnkBNMSj1PcDsQxPrntLYa6cUNFoFexqWaGBlM63q/i6RzAM5tpkA835VINkHks XIg43NYlGS50vEAZ0D6+OpS9CAZPeW48TX3kzUn0suAAeDjq/iGJMANX12yjskDchAbM e6Ti8TNwxtrISpcWbcHQ7kC1QMAMgq7wfAgNpu9GI1g7fswrr4h3Z73m4MM5hulBCj5s +6/A== X-Gm-Message-State: ACrzQf3XgEdKGXs9uUk31V5ilO6hN+6Y2A1EJ5WbM4Go7J9SJhVJrvE4 2FXHEkqtgV11PHPKxvmh5uYzrQ== X-Google-Smtp-Source: AMsMyM4innxfNZAzhGWL/DpqnIwUOYEYiApzjV6DBWLPdx0UZXtA4mdOwut8gE2N2aGulndGyPlvSA== X-Received: by 2002:a63:7909:0:b0:458:1ba6:ec80 with SMTP id u9-20020a637909000000b004581ba6ec80mr44062420pgc.414.1666898002301; Thu, 27 Oct 2022 12:13:22 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id q10-20020a170903204a00b00176e6f553efsm1525222pla.84.2022.10.27.12.13.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 27 Oct 2022 12:13:21 -0700 (PDT) Date: Thu, 27 Oct 2022 12:13:20 -0700 From: Kees Cook To: Andrey Konovalov Cc: Christoph Lameter , Dmitry Vyukov , Jakub Kicinski , Paolo Abeni , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Andrey Ryabinin , Alexander Potapenko , Vincenzo Frascino , linux-mm@kvack.org, kasan-dev@googlegroups.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH] mm: Make ksize() a reporting-only function Message-ID: <202210271212.EB69EF1@keescook> References: <20221022180455.never.023-kees@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1666898003; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=KRy9sqvf0ZM2bZpgrnftqxmIbppdN+rJl6H1sXbtcEA=; b=01Y/J3MSFlorrIPjM2GrmLR+L/F9+80KjCs0Lp1E5wxGMddA1l6FbT7ZlfFMzp4+5h66HQ Fnj9lrwxmsQGbEs43QVKiyjLk7tsvROlNpxjAHc8IrLJbmenGyf2wkcAf53yK0PIjJ+tCB 8bPMmXTY4mUgOVZwiPWSRnMEEQ9mtlE= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=ePBvbYsq; spf=pass (imf14.hostedemail.com: domain of keescook@chromium.org designates 209.85.210.181 as permitted sender) smtp.mailfrom=keescook@chromium.org; dmarc=pass (policy=none) header.from=chromium.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1666898003; a=rsa-sha256; cv=none; b=5mgAyX7VFrZ8KYIt2/x/82qehgGldDEGWFXUqN7gQWl77E55mhW4N6QqSuDdGUbVx6hWJi IqL8vWyAF7UEmDEHkP8Wg0SX2PankfXkJ2ZCzX4TWJSk0eLolDjvnYoUWvx9kyCoHmgqjX bQ1IKAUpqFuQJ+zVeKFE2ICRWid3wNU= X-Stat-Signature: zramr4edsdmj9r4rabj4qhy9q4rddkuj X-Rspamd-Queue-Id: 6BEF3100005 Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=ePBvbYsq; spf=pass (imf14.hostedemail.com: domain of keescook@chromium.org designates 209.85.210.181 as permitted sender) smtp.mailfrom=keescook@chromium.org; dmarc=pass (policy=none) header.from=chromium.org X-Rspam-User: X-Rspamd-Server: rspam01 X-HE-Tag: 1666898003-464950 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 Thu, Oct 27, 2022 at 09:05:45PM +0200, Andrey Konovalov wrote: > On Sat, Oct 22, 2022 at 8:08 PM Kees Cook wrote: > [...] > > -/* Check that ksize() makes the whole object accessible. */ > > +/* Check that ksize() does NOT unpoison whole object. */ > > static void ksize_unpoisons_memory(struct kunit *test) > > { > > char *ptr; > > @@ -791,15 +791,17 @@ static void ksize_unpoisons_memory(struct kunit *test) > > > > ptr = kmalloc(size, GFP_KERNEL); > > KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); > > + > > real_size = ksize(ptr); > > + KUNIT_EXPECT_GT(test, real_size, size); > > > > OPTIMIZER_HIDE_VAR(ptr); > > > > /* This access shouldn't trigger a KASAN report. */ > > - ptr[size] = 'x'; > > + ptr[size - 1] = 'x'; > > > > /* This one must. */ > > - KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[real_size]); > > + KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)ptr)[real_size - 1]); > > How about also accessing ptr[size] here? It would allow for a more > precise checking of the in-object redzone. Sure! Probably both ptr[size] and ptr[real_size -1], yes? -- Kees Cook