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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED autolearn=ham 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 ACA79ECDFB8 for ; Wed, 18 Jul 2018 14:50:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 609722075C for ; Wed, 18 Jul 2018 14:50:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linaro.org header.i=@linaro.org header.b="TznRaq0s" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 609722075C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731041AbeGRP24 (ORCPT ); Wed, 18 Jul 2018 11:28:56 -0400 Received: from mail-io0-f196.google.com ([209.85.223.196]:46398 "EHLO mail-io0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730499AbeGRP24 (ORCPT ); Wed, 18 Jul 2018 11:28:56 -0400 Received: by mail-io0-f196.google.com with SMTP id i18-v6so4301114ioj.13 for ; Wed, 18 Jul 2018 07:50:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=6PqGTrnoFqomKK2IGI+iecZRX7MxoapEwQIIosfEGs0=; b=TznRaq0sedNyZPRo7D+KHVxf5s+3/oGdBjSfA5tZTQnBw7md0pmnpAua9W+0I2PIgL qcqaBj4suk/ywz7ZLfv5BQz3xYjkN76iIQl2LOVYAtIcaRumb9Y1g4eRfYyMG/OUM3oG 6G82NDNI6Skhe+JxPq2HIV6vdmA6eD9U6om6c= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=6PqGTrnoFqomKK2IGI+iecZRX7MxoapEwQIIosfEGs0=; b=IMvOlaIr8jO7Ee0hrBcih5VBaOR9lb9nKFnjhAJ7DFuYGEwZNocZNVYcM686Q/X2Xo h80Ygtcu8yuV4N0QTPYUV6M+iqD25jYuJM0lFm/59+tkfeOMuNYDr0W/Kg11T2xvUHAY MAj+W8zavHl7YIiCkEdkcZqMtENoqWHhzgijCvyC5m8Rtuhl0mmmzGqfgm9+AzBZTN9y +P68VKyEIUxvvgoT4cjBIyc6Wex7DX0ih9quf2RHRqwoI17rI2HVNn/Gv9FBq1u+0mBG ge3kmDKyhPBefaQB0aKxmQL9sxY0RNJvxzQwtd9VEqfdWj5wN1lib5ab/f+jNYF0y11v 2hmg== X-Gm-Message-State: AOUpUlHNgxoLw7gvDljZsowX5Wg5FOoYaHMp9yGcc3GqQBB5TTGAzL79 KwPcP1O2E4k6DJ5EYJwhIfw9Mr0fQMYeT9SoCrEUcA== X-Google-Smtp-Source: AAOMgpfK837Fwp8zQIJtcYHMxxAqTRIle9HeFVbsniQ4J1M2ySlLZR3kTcK0924mS3Iw1C5cDFTiaXGvLNRAgaoSeuY= X-Received: by 2002:a6b:5208:: with SMTP id g8-v6mr5516940iob.60.1531925439854; Wed, 18 Jul 2018 07:50:39 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:a6b:ac05:0:0:0:0:0 with HTTP; Wed, 18 Jul 2018 07:50:39 -0700 (PDT) In-Reply-To: References: <20180711203619.1020-1-keescook@chromium.org> <20180711203619.1020-12-keescook@chromium.org> <20180713004038.lwibdesz7ohhoind@gondor.apana.org.au> <20180713034406.zwu2pkp3f2onybxs@gondor.apana.org.au> <20180713052029.cfo24bsr5swtbdja@gondor.apana.org.au> From: Ard Biesheuvel Date: Wed, 18 Jul 2018 23:50:39 +0900 Message-ID: Subject: Re: [PATCH v4 11/14] treewide: Prepare to remove VLA usage for AHASH_REQUEST_ON_STACK To: Arnd Bergmann Cc: Kees Cook , Herbert Xu , "Gustavo A. R. Silva" , Eric Biggers , Alasdair Kergon , Giovanni Cabiddu , Lars Persson , Mike Snitzer , Rabin Vincent , Tim Chen , "David S. Miller" , Masahiro Yamada , "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" , qat-linux@intel.com, dm-devel@redhat.com, Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 18 July 2018 at 05:59, Arnd Bergmann wrote: > On Sun, Jul 15, 2018 at 6:28 AM, Kees Cook wrote: >> >> After my ahash to shash conversions, only ccm is left as an ahash >> user, since it actually uses sg. But with the hard-coded value reduced >> to 376, this doesn't trip the frame warnings any more. :) >> >> I'll send an updated series soon. > > Maybe we should get rid of that one as well then and remove > AHASH_REQUEST_ON_STACK()? > > I see that Ard (now on Cc) added this usage only recently. Looking > at the code some more, I also find that the descsize is probably > much smaller than 376 for all possible cases of "cbcmac(*)", > either alg->cra_blocksize plus a few bytes or sizeof(mac_desc_ctx) > (i.e. 20) for arch/arm64/crypto/aes-glue.c. > > Walking the sglist here means open-coding a shash_ahash_update() > implementation in crypto_ccm_auth(), that that doesn't seem to > add much complexity over what it already has to do to chain > the sglist today. > It would be better to add a variably sized ahash request member to struct crypto_ccm_req_priv_ctx, the only problem is that the last member of that struct (skreq) is variably sized already, so it would involve having a struct ahash_request pointer pointing into the same struct, after the skreq member.