linux-kernel - Re: [PATCH v9 06/29] x86/mpx: Use signed variables to compute effective addresses

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Message-ID: <1507225100.13798.0.camel@intel.com>
Date:   Thu, 5 Oct 2017 17:38:40 +0000
From:   "Neri, Ricardo" <ricardo.neri@...el.com>
To:     "bp@...e.de" <bp@...e.de>
CC:     "corbet@....net" <corbet@....net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "peterz@...radead.org" <peterz@...radead.org>,
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        "Ren, Qiaowei" <qiaowei.ren@...el.com>,
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Subject: Re: [PATCH v9 06/29] x86/mpx: Use signed variables to compute
 effective addresses

On Thu, 2017-10-05 at 11:41 +0200, Borislav Petkov wrote:
> On Tue, Oct 03, 2017 at 08:54:09PM -0700, Ricardo Neri wrote:
> > 
> > Even though memory addresses are unsigned, the operands used to compute the
> > effective address do have a sign. This is true for ModRM.rm, SIB.base,
> > SIB.index as well as the displacement bytes. Thus, signed variables shall
> > be used when computing the effective address from these operands. Once the
> > signed effective address has been computed, it is casted to an unsigned
> > long to determine the linear address.
> > 
> > Variables are renamed to better reflect the type of address being
> > computed.
> > 
> > Cc: Borislav Petkov <bp@...e.de>
> > Cc: Andy Lutomirski <luto@...nel.org>
> > Cc: Dave Hansen <dave.hansen@...ux.intel.com>
> > Cc: Adam Buchbinder <adam.buchbinder@...il.com>
> > Cc: Colin Ian King <colin.king@...onical.com>
> > Cc: Lorenzo Stoakes <lstoakes@...il.com>
> > Cc: Qiaowei Ren <qiaowei.ren@...el.com>
> > Cc: Peter Zijlstra <peterz@...radead.org>
> > Cc: Nathan Howard <liverlint@...il.com>
> > Cc: Adan Hawthorn <adanhawthorn@...il.com>
> > Cc: Joe Perches <joe@...ches.com>
> > Cc: Ravi V. Shankar <ravi.v.shankar@...el.com>
> > Cc: x86@...nel.org
> > Signed-off-by: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
> > ---
> >  arch/x86/mm/mpx.c | 20 ++++++++++++++------
> >  1 file changed, 14 insertions(+), 6 deletions(-)
> Reviewed-by: Borislav Petkov <bp@...e.de>

Thank you!

BR,
Ricardo