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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C5D4AC433EF for ; Mon, 24 Jan 2022 18:24:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245186AbiAXSYn (ORCPT ); Mon, 24 Jan 2022 13:24:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37086 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245221AbiAXSYf (ORCPT ); Mon, 24 Jan 2022 13:24:35 -0500 Received: from mail-pl1-x62f.google.com (mail-pl1-x62f.google.com [IPv6:2607:f8b0:4864:20::62f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A0447C06173D for ; Mon, 24 Jan 2022 10:24:35 -0800 (PST) Received: by mail-pl1-x62f.google.com with SMTP id b15so1944153plg.3 for ; Mon, 24 Jan 2022 10:24:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=uhZIz3/JykOBz9VP0YFQFFJB6JHp3P7kosVSER8JbCs=; b=alUnBjwA9GnJNcB1VQbp/WSOeoyPUm7ct70T0RMkE/CVfVe0iGp5KNjxhHwR40ceTB 6amxmfkC0OCiiUzzNflT0LH8nbTiIXGFiCnRTzrzB1Zm94fqLJkT7M5ODG5wwtdaegO4 q9dcoLaWBG29OEiHULjhmJXDUEbMQUlUoOw/4= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=uhZIz3/JykOBz9VP0YFQFFJB6JHp3P7kosVSER8JbCs=; b=N9s/fIl9MF1dNm+PnhBEkNiPX4pBtdkXGvGODHJbNrikL6dJWJKHZt+tcZa90vtyc7 OXDW6yi52iNhjusVrNvXN9k7DtRib3TotnTyMzlghDpR/uyjwFY/2qmV0V2bNMCxwlib dXskzNwIif/95Z6pNYb2u1pTn8f/+caw5jbPOWZPqlRxwV/q6DC3cIK/LBX6L+Ihi22G 37g2136Fd/fyrQdaM03S0zYSJLxN0LpflGDZZZZ1RZJ2d/Ptl/X1/MGi8W6VssZTbKgP iUAWQyMyt+fgtChJve3BHctYjnfUlcu0s/nLsBTCKakqWy9QYt9cHMdHxG5SGyCWMNYN Pfew== X-Gm-Message-State: AOAM530fVYNGu/xM+8jSCaojl+7oNH/ABtRA4Ac3clE7U9pRcOcylw0X aeOTXrND+RezZdW+CGImKdElRQ== X-Google-Smtp-Source: ABdhPJx/8XSSCE4pNF/rMKWRrUHHg7PdBjMRFPZ0Ya0DtIbcSeRdq+8k4YOK6JIR4In6vxCm3Y1BZw== X-Received: by 2002:a17:902:bc88:b0:149:2032:6bcf with SMTP id bb8-20020a170902bc8800b0014920326bcfmr15462814plb.44.1643048675213; Mon, 24 Jan 2022 10:24:35 -0800 (PST) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id e1sm12311920pgu.17.2022.01.24.10.24.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 24 Jan 2022 10:24:34 -0800 (PST) Date: Mon, 24 Jan 2022 10:24:34 -0800 From: Kees Cook To: Marco Elver Cc: Andrew Morton , Andrey Ryabinin , Alexander Potapenko , Andrey Konovalov , Dmitry Vyukov , kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Brendan Higgins , linux-hardening@vger.kernel.org, Nico Pache Subject: Re: [PATCH] kasan: test: fix compatibility with FORTIFY_SOURCE Message-ID: <202201241024.DA581869@keescook> References: <20220124160744.1244685-1-elver@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220124160744.1244685-1-elver@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org On Mon, Jan 24, 2022 at 05:07:44PM +0100, Marco Elver wrote: > With CONFIG_FORTIFY_SOURCE enabled, string functions will also perform > dynamic checks using __builtin_object_size(ptr), which when failed will > panic the kernel. > > Because the KASAN test deliberately performs out-of-bounds operations, > the kernel panics with FORITY_SOURCE, for example: > > | kernel BUG at lib/string_helpers.c:910! > | invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI > | CPU: 1 PID: 137 Comm: kunit_try_catch Tainted: G B 5.16.0-rc3+ #3 > | Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 > | RIP: 0010:fortify_panic+0x19/0x1b > | ... > | Call Trace: > | > | kmalloc_oob_in_memset.cold+0x16/0x16 > | ... > > Fix it by also hiding `ptr` from the optimizer, which will ensure that > __builtin_object_size() does not return a valid size, preventing > fortified string functions from panicking. > > Reported-by: Nico Pache > Signed-off-by: Marco Elver Yup, more good fixes. Thanks! Reviewed-by: Kees Cook -- Kees Cook