Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Arvind Sankar <nivedita@alum.mit.edu>
Date:   Wed, 11 Mar 2020 23:52:37 -0400
To:     Pavel Machek <pavel@denx.de>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        Ard Biesheuvel <ardb@kernel.org>,
        Ingo Molnar <mingo@kernel.org>, linux-efi@vger.kernel.org,
        Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 4.19 84/86] efi/x86: Handle by-ref arguments covering
 multiple pages in mixed mode
Message-ID: <20200312035235.GA270934@rani.riverdale.lan>
References: <20200310124530.808338541@linuxfoundation.org>
 <20200310124535.409134291@linuxfoundation.org>
 <20200311130106.GB7285@duo.ucw.cz>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <20200311130106.GB7285@duo.ucw.cz>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed, Mar 11, 2020 at 02:01:07PM +0100, Pavel Machek wrote:
> We don't really need to do this computation on pa, it would work on va
> as well, right? It does not matter much, but old code worked that way.
> 
> Plus, strictly speaking, pa + size can overflow for huge sizes, and
> test will return false negatives.

This is 64-bit code, overflow would need pa + size to be bigger than
2^64, and even then a false negative would need size to be around 2^64.