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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 23E88C433EF for ; Wed, 13 Oct 2021 11:51:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 05B28610D0 for ; Wed, 13 Oct 2021 11:51:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231145AbhJMLxi (ORCPT ); Wed, 13 Oct 2021 07:53:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40932 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229580AbhJMLxh (ORCPT ); Wed, 13 Oct 2021 07:53:37 -0400 Received: from mail-wr1-x432.google.com (mail-wr1-x432.google.com [IPv6:2a00:1450:4864:20::432]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AB4D6C061746 for ; Wed, 13 Oct 2021 04:51:34 -0700 (PDT) Received: by mail-wr1-x432.google.com with SMTP id u18so7476750wrg.5 for ; Wed, 13 Oct 2021 04:51:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=date:from:to:cc:subject:message-id:mail-followup-to:references :mime-version:content-disposition:in-reply-to; bh=vki2MOpHiPRjF8WV03xObL8WLrTT/QCXIdeoymbkrg4=; b=HOpvbV/8VIT89xQR1G4qB0gn/wkeFr8tbi7t7Ej6scW9DiwHBv0LY+jJ7JSgoE6KyU ZKyYEyAPrAtFtBiWCENUNiCOHeHWltxgzVqvUv9juywA/4hMMtJV05+HobRwvzQ6gnfu YRNTwUtzRrjTIr12GISb0kYjCbUdwoXkepK6g= 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 :mail-followup-to:references:mime-version:content-disposition :in-reply-to; bh=vki2MOpHiPRjF8WV03xObL8WLrTT/QCXIdeoymbkrg4=; b=kAVpWdKb3bhv9QStOvVhc9Cvdea4mX+XDjA2epCDinZzk9arkqE+3WypCetpvdNN0s x7lVB6nLzToz/mfTDD8nxSpuPekbE90eTOOwE7jiq8Gsex202BfNUoBIHEVBVoWXBguk Ykwy1QHbwwLSDExsMZK/2GogoAo4CYzs6oppdHDQNi8ZXoi2xybXb9p/X/MCPz0hepNG l5JGeeqoo5cUBoFQEgGUouuAcXAibV3vQYA+ZofwfI6LwvlaGp4NyBJ2QHT8uywUMdOn 7TTMtGCMxV2+CDjdtXLoL6EFKy1IYU5oHA28PqMb1irWkG7+wThSxmwH3eQxrq7iMD0a u/0g== X-Gm-Message-State: AOAM530nHGI+7Q3oYMTd60FEEfsvxWQ0Fs30Z6SU3EVH2iYoQQCfRKKm XLM4vWwI/gfU4zCW156q7RbPeA== X-Google-Smtp-Source: ABdhPJyqMmgpu2ql1/ClhZBIYGjM/oxKKvUtKMfYyVBZ/3VbeIdFLbpRezHwmnmwnj2CHBJT0vE0iA== X-Received: by 2002:a05:600c:154a:: with SMTP id f10mr12123883wmg.184.1634125892773; Wed, 13 Oct 2021 04:51:32 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id b10sm8533490wrf.68.2021.10.13.04.51.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Oct 2021 04:51:32 -0700 (PDT) Date: Wed, 13 Oct 2021 13:51:30 +0200 From: Daniel Vetter To: Jani Nikula Cc: Len Baker , Joonas Lahtinen , Rodrigo Vivi , David Airlie , Daniel Vetter , Kees Cook , "Gustavo A. R. Silva" , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] drm/i915: Prefer struct_size over open coded arithmetic Message-ID: Mail-Followup-To: Jani Nikula , Len Baker , Joonas Lahtinen , Rodrigo Vivi , David Airlie , Kees Cook , "Gustavo A. R. Silva" , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org References: <20211003104258.18550-1-len.baker@gmx.com> <20211011092304.GA5790@titan> <87k0ihxj56.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87k0ihxj56.fsf@intel.com> X-Operating-System: Linux phenom 5.10.0-8-amd64 Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org On Wed, Oct 13, 2021 at 02:24:05PM +0300, Jani Nikula wrote: > On Mon, 11 Oct 2021, Len Baker wrote: > > Hi, > > > > On Sun, Oct 03, 2021 at 12:42:58PM +0200, Len Baker wrote: > >> As noted in the "Deprecated Interfaces, Language Features, Attributes, > >> and Conventions" documentation [1], size calculations (especially > >> multiplication) should not be performed in memory allocator (or similar) > >> function arguments due to the risk of them overflowing. This could lead > >> to values wrapping around and a smaller allocation being made than the > >> caller was expecting. Using those allocations could lead to linear > >> overflows of heap memory and other misbehaviors. > >> > >> In this case these are not actually dynamic sizes: all the operands > >> involved in the calculation are constant values. However it is better to > >> refactor them anyway, just to keep the open-coded math idiom out of > >> code. > >> > >> So, add at the end of the struct i915_syncmap a union with two flexible > >> array members (these arrays share the same memory layout). This is > >> possible using the new DECLARE_FLEX_ARRAY macro. And then, use the > >> struct_size() helper to do the arithmetic instead of the argument > >> "size + count * size" in the kmalloc and kzalloc() functions. > >> > >> Also, take the opportunity to refactor the __sync_seqno and __sync_child > >> making them more readable. > >> > >> This code was detected with the help of Coccinelle and audited and fixed > >> manually. > >> > >> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments > >> > >> Signed-off-by: Len Baker > >> --- > >> drivers/gpu/drm/i915/i915_syncmap.c | 12 ++++++++---- > >> 1 file changed, 8 insertions(+), 4 deletions(-) > > > > I received a mail telling that this patch doesn't build: > > > > == Series Details == > > > > Series: drm/i915: Prefer struct_size over open coded arithmetic > > URL : https://patchwork.freedesktop.org/series/95408/ > > State : failure > > > > But it builds without error against linux-next (tag next-20211001). Against > > which tree and branch do I need to build? > > drm-tip [1]. It's a sort of linux-next for graphics. I think there are > still some branches that don't feed to linux-next. Yeah we need to get gt-next in linux-next asap. Joonas promised to send out his patch to make that happen in dim. -Daniel > > BR, > Jani. > > > [1] https://cgit.freedesktop.org/drm/drm-tip > > > > > > Regards, > > Len > > -- > Jani Nikula, Intel Open Source Graphics Center -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch