From: Dave Hansen <dave.hansen@intel.com>
To: Jarkko Sakkinen <jarkko@kernel.org>, Shuah Khan <shuah@kernel.org>
Cc: linux-kselftest@vger.kernel.org, linux-sgx@vger.kernel.org,
Reinette Chatre <reinette.chatre@intel.com>,
Borislav Petkov <bp@alien8.de>,
Tianjia Zhang <tianjia.zhang@linux.alibaba.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Jethro Beekman <jethro@fortanix.com>,
Borislav Petkov <bp@suse.de>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/4] selftests/sgx: Fix Q1 and Q2 calculation in sigstruct.c
Date: Tue, 6 Jul 2021 13:53:20 -0700 [thread overview]
Message-ID: <4303b822-5861-ba2c-f620-0e752e499329@intel.com> (raw)
In-Reply-To: <20210705143652.116125-3-jarkko@kernel.org>
On 7/5/21 7:36 AM, Jarkko Sakkinen wrote:
> From: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
>
> 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: 2adcba79e69d ("selftests/x86: Add a selftest for SGX")
> Link: https://lore.kernel.org/linux-sgx/20210301051836.30738-1-tianjia.zhang@linux.alibaba.com/
> Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
> Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
This looks fine, but can I suggest a Subject: tweak?
selftests/sgx: Fix calculations for sub-maximum field sizes
In any case:
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
next prev parent reply other threads:[~2021-07-06 20:53 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20210705143652.116125-1-jarkko@kernel.org>
2021-07-05 14:36 ` [PATCH 1/4] x86/sgx: Add sgx_nr_all_pages to the debugfs Jarkko Sakkinen
2021-07-06 14:56 ` Dave Hansen
2021-07-06 15:39 ` Greg KH
2021-07-06 22:08 ` Jarkko Sakkinen
2021-07-05 14:36 ` [PATCH 2/4] selftests/sgx: Fix Q1 and Q2 calculation in sigstruct.c Jarkko Sakkinen
2021-07-06 20:53 ` Dave Hansen [this message]
2021-07-06 23:52 ` Jarkko Sakkinen
2021-07-05 14:36 ` [PATCH 3/4] selftests/sgx: Assign source for each segment Jarkko Sakkinen
2021-07-05 14:36 ` [PATCH 4/4] selftests/sgx: Trigger the reclaimer and #PF handler Jarkko Sakkinen
2021-07-06 18:34 ` Reinette Chatre
2021-07-06 23:50 ` Jarkko Sakkinen
2021-07-07 0:10 ` Reinette Chatre
2021-07-07 9:17 ` Jarkko Sakkinen
2021-07-07 15:02 ` Reinette Chatre
2021-07-07 20:50 ` Jarkko Sakkinen
2021-07-07 21:20 ` Reinette Chatre
2021-07-09 16:22 ` Jarkko Sakkinen
2021-07-07 21:20 ` Dave Hansen
2021-07-09 16:25 ` Jarkko Sakkinen
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