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Date: Wed, 5 Mar 2025 02:19:08 +0200
From: Jarkko Sakkinen <jarkko@kernel.org>
To: Dave Hansen <dave.hansen@intel.com>
Cc: linux-integrity@vger.kernel.org,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Dan Carpenter <dan.carpenter@linaro.org>, linux-sgx@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] arch/x86: Fix size overflows in sgx_encl_create()
Message-ID: <Z8eYfALmwN68F39V@kernel.org>
References: <20250305000602.127665-1-jarkko@kernel.org>
 <8255b211-5510-4c09-b13f-c4e3bd0d0aba@intel.com>
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In-Reply-To: <8255b211-5510-4c09-b13f-c4e3bd0d0aba@intel.com>

On Tue, Mar 04, 2025 at 04:18:03PM -0800, Dave Hansen wrote:
> On 3/4/25 16:06, Jarkko Sakkinen wrote:
> > +	/*
> > +	 * This is a micro-architectural requirement. ECREATE would detect this
> > +	 * too without mentionable overhead but this check guarantees also that
> > +	 * the space calculations for EPC and shmem allocations never overflow.
> > +	 */
> > +	if (!is_power_of_2(secs->size))
> > +		return -EINVAL;
> 
> Isn't it a plain old documented architectural requirement?

Yes, but it requires some explanation why it exists here instead of
counting on ECREATE.

What do you suggest?

BR, Jarkko