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=-6.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no 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 13135C4338F for ; Sun, 22 Aug 2021 13:24:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EA11A61245 for ; Sun, 22 Aug 2021 13:24:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232148AbhHVNYr (ORCPT ); Sun, 22 Aug 2021 09:24:47 -0400 Received: from mail.kernel.org ([198.145.29.99]:48506 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230495AbhHVNYo (ORCPT ); Sun, 22 Aug 2021 09:24:44 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id CB99A61354; Sun, 22 Aug 2021 13:24:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1629638643; bh=+0KLb9o630gwsAklksMT+OiAbRBsvMLZHD8SBqtnUus=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=iTpGkQGBW0QaKllQHFS84RT2heM9sXV/6IKcYuEeJcpP02OJpX/7OlimUA8o/bntn z9xstex+4bb0M0IhMs3sEkvM+NKX9/pW8HtJd3rm8e6/jrY7bHWzoOQsz4vDveyQko W/BYR1/Ii6BM78f1eq2XZeuI/BQIz8URji4HTqViv8nOAzMjuw0FMzBYCXn8Q+UZK+ 79NvwGYIxGRevspoJ/xRpPP0yegpKafCjsAAv+LFzzRlhLEpoN4UIZE6KEOYQb+ZU5 bNTBfyPm51Ndu0dybfJtdkmPqEeepwuqUAL2NwZXXGjhkWy0D8aojo0K7kGSPXivf1 /LREEZ8gHGi2A== Received: by mail-oo1-f54.google.com with SMTP id t2-20020a4ae9a2000000b0028c7144f106so3447283ood.6; Sun, 22 Aug 2021 06:24:03 -0700 (PDT) X-Gm-Message-State: AOAM532DqJNXpOm1HCboIupGBctodFbi8Wv0wGek20Q6sR0V2SOmqmNN xpBViYvUi1R9uETBivnuMD8ZJrxSDOg+6p57oFc= X-Google-Smtp-Source: ABdhPJyFgHF/pYD3PAz8sWJVS2fTtBUpAQY87RdiATdCa+OOpC4w2u+fSSW6TcgHyDZxt+I7QmDh7PTmPTldhDarXQ4= X-Received: by 2002:a4a:dfac:: with SMTP id k12mr22727674ook.41.1629638643184; Sun, 22 Aug 2021 06:24:03 -0700 (PDT) MIME-Version: 1.0 References: <20210809141027.860850-1-chouhan.shreyansh630@gmail.com> <20210820083111.GA28484@gondor.apana.org.au> <20210820125315.GB28484@gondor.apana.org.au> In-Reply-To: <20210820125315.GB28484@gondor.apana.org.au> From: Ard Biesheuvel Date: Sun, 22 Aug 2021 15:23:52 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] crypto: xts_crypt() return if walk.nbytes is 0 To: Herbert Xu Cc: Shreyansh Chouhan , "David S. Miller" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , X86 ML , "H. Peter Anvin" , Linux Crypto Mailing List , Linux Kernel Mailing List , syzbot+20191dc583eff8602d2d@syzkaller.appspotmail.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 20 Aug 2021 at 14:53, Herbert Xu wrote: > > On Fri, Aug 20, 2021 at 01:14:52PM +0200, Ard Biesheuvel wrote: > > > > In spite of that, I have a slight preference for this version, given > > that it makes it obvious that we bail on two separate conditions: > > - an error has occurred > > - no error has occurred but the resulting walk is empty > > > > Testing walk.nbytes only needlessly obfuscates the code, as we need to > > return 'err' in the end anyway. > > I disagree, this is how most skcipher walkers are structured, they > never explicitly test on err and only terminate the loop when > walk->nbytes hits zero, in which case err is returned as is. > > I don't see why this particular skcipher walker should deviate > from that paradigm. In fact it is exactly that deviation that > caused the bug in the first instance. > Fair enough.