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=-16.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 34453C4320A for ; Tue, 27 Jul 2021 03:12:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 174FC6101E for ; Tue, 27 Jul 2021 03:12:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234699AbhG0CcC (ORCPT ); Mon, 26 Jul 2021 22:32:02 -0400 Received: from mail.kernel.org ([198.145.29.99]:44654 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234422AbhG0CcC (ORCPT ); Mon, 26 Jul 2021 22:32:02 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id C728160FF4; Tue, 27 Jul 2021 03:12:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1627355550; bh=byJUzmas4bh9ocUTUqQ3pGJIs/Wyhxir7SmarkwejNE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=b1eh/9iTqMQ/kk0G/DkQOprlmWqOxRA9cL0zaKqHq/Kda7JxuusEznA/OZtph6Flq 460LpqjN8rehK7qEOvFHfP2Yj5gAKzIcxFrNECEaVhwySvVxCa7+i0DXura37+uRL8 uXh1/IR6C/xeDBe4pfXghM0FVmFY4GZrirJqHIytRsIrFUBTfo/MaqdJi47TCkZp2+ PNzLa4gpXYojn0b84lGyhsNSGpQwlxcgsvmwKMPsanltQVvmfcvy3pXmBrCx5gB5Fr Q8QErSe72StMxcAUs6w1OcmfT3IW/3YXJxaCIovXz36P0vJnHDugqDAvgsVhk3NGHS 8lHuimkLrfzjA== Date: Tue, 27 Jul 2021 06:12:27 +0300 From: Jarkko Sakkinen To: Shuah Khan Cc: Shuah Khan , linux-kselftest@vger.kernel.org, linux-sgx@vger.kernel.org, Reinette Chatre , Borislav Petkov , Tianjia Zhang , Dave Hansen , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] selftests/sgx: Fix Q1 and Q2 calculation in sigstruct.c Message-ID: <20210727031227.tx2gqx2qg3mg4522@kernel.org> References: <20210705050922.63710-1-jarkko@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On Fri, Jul 23, 2021 at 01:53:06PM -0600, Shuah Khan wrote: > On 7/4/21 11:09 PM, Jarkko Sakkinen wrote: > > From: Tianjia Zhang > > > > Q1 and Q2 are numbers with *maximum* length of 384 bytes. If the calculated > > length of Q1 and Q2 is less than 384 bytes, things will go wrong. > > > > E.g. if Q2 is 383 bytes, then > > > > 1. The bytes of q2 are copied to sigstruct->q2 in calc_q1q2(). > > 2. The entire sigstruct->q2 is reversed, which results it being > > 256 * Q2, given that the last byte of sigstruct->q2 is added > > to before the bytes given by calc_q1q2(). > > > > Either change in key or measurement can trigger the bug. E.g. an unmeasured > > heap could cause a devastating change in Q1 or Q2. > > > > Reverse exactly the bytes of Q1 and Q2 in calc_q1q2() before returning to > > the caller. > > > > Fixes: dedde2634570 ("selftests/sgx: Trigger the reclaimer in the selftests") > > Link: https://lore.kernel.org/linux-sgx/20210301051836.30738-1-tianjia.zhang@linux.alibaba.com/ > > Signed-off-by: Tianjia Zhang > > Signed-off-by: Jarkko Sakkinen > > --- > > The original patch did a bad job explaining the code change but it > > turned out making sense. I wrote a new description. > > > > v2: > > - Added a fixes tag. > > tools/testing/selftests/sgx/sigstruct.c | 41 +++++++++++++------------ > > 1 file changed, 21 insertions(+), 20 deletions(-) > > > > diff --git a/tools/testing/selftests/sgx/sigstruct.c b/tools/testing/selftests/sgx/sigstruct.c > > index dee7a3d6c5a5..92bbc5a15c39 100644 > > --- a/tools/testing/selftests/sgx/sigstruct.c > > +++ b/tools/testing/selftests/sgx/sigstruct.c > > @@ -55,10 +55,27 @@ static bool alloc_q1q2_ctx(const uint8_t *s, const uint8_t *m, > > return true; > > } > > +static void reverse_bytes(void *data, int length) > > +{ > > + int i = 0; > > + int j = length - 1; > > + uint8_t temp; > > + uint8_t *ptr = data; > > + > > + while (i < j) { > > + temp = ptr[i]; > > + ptr[i] = ptr[j]; > > + ptr[j] = temp; > > + i++; > > + j--; > > + } > > +} > > I was just about apply this one and noticed this reverse_bytes(). > Aren't there byteswap functions you could call instead of writing > your own? Sorry for latency, just came from two week leave. glibc does provide bswap for 16, 32, 64 bit numbers but nothing better. I have no idea if libssl has such function. Since the test code already uses this function, and it works, and it's not a newly added function in this patch, I would consider keeping it. > thanks, > -- Shuah /Jarkko