linux-kernel - RE: [RFCv2 06/10] x86/uaccess: Remove tags from the address before checking

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Date:   Thu, 12 May 2022 13:02:55 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     "'Kirill A. Shutemov'" <kirill.shutemov@...ux.intel.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        "Peter Zijlstra" <peterz@...radead.org>
CC:     "x86@...nel.org" <x86@...nel.org>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        "Dmitry Vyukov" <dvyukov@...gle.com>,
        "H . J . Lu" <hjl.tools@...il.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Rick Edgecombe <rick.p.edgecombe@...el.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [RFCv2 06/10] x86/uaccess: Remove tags from the address before
 checking

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

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