Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   David Laight <David.Laight@ACULAB.COM>
To:     "'Kirill A. Shutemov'" <kirill.shutemov@linux.intel.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Andy Lutomirski <luto@kernel.org>,
        "Peter Zijlstra" <peterz@infradead.org>
CC:     "x86@kernel.org" <x86@kernel.org>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Alexander Potapenko <glider@google.com>,
        "Dmitry Vyukov" <dvyukov@google.com>,
        "H . J . Lu" <hjl.tools@gmail.com>,
        Andi Kleen <ak@linux.intel.com>,
        Rick Edgecombe <rick.p.edgecombe@intel.com>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [RFCv2 06/10] x86/uaccess: Remove tags from the address before
 checking
Thread-Topic: [RFCv2 06/10] x86/uaccess: Remove tags from the address before
 checking
Thread-Index: AQHYZN8hTSKv+xBtAEiDWI98RCjTSK0bNyYw
Date:   Thu, 12 May 2022 13:02:55 +0000
Message-ID: <be77009d1b164abc9ff7a71068aa9c08@AcuMS.aculab.com>
References: <20220511022751.65540-1-kirill.shutemov@linux.intel.com>
 <20220511022751.65540-8-kirill.shutemov@linux.intel.com>
In-Reply-To: <20220511022751.65540-8-kirill.shutemov@linux.intel.com>
Accept-Language: en-GB, en-US
MIME-Version: 1.0
Content-Language: en-US
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8BIT
Precedence: bulk

From: Kirill A. Shutemov
> Sent: 11 May 2022 03:28
> 
> The tags must not be included into check whether it's okay to access the
> userspace address.
> 
> Strip tags in  access_ok().

Why?
Just change the test to check the buffer doesn't cross 1u << 63.


	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)