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Date: Wed, 18 Mar 2015 16:45:00 -0000
Message-ID: <CAMe9rOq0fw+b+UGvRs-Fr3+43ud7jy9xe_EKsP0oXftB+0UdiA@mail.gmail.com>
Subject: Re: [PATCH, libmpx, i386, PR driver/65444] Pass '-z bndplt' when building dynamic objects with MPX
From: "H.J. Lu" <hjl.tools@gmail.com>
To: Ilya Enkovich <enkovich.gnu@gmail.com>
Cc: Jakub Jelinek <jakub@redhat.com>, Richard Biener <richard.guenther@gmail.com>, 	GCC Patches <gcc-patches@gcc.gnu.org>, Uros Bizjak <ubizjak@gmail.com>
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On Wed, Mar 18, 2015 at 9:14 AM, Ilya Enkovich <enkovich.gnu@gmail.com> wrote:
> 2015-03-18 17:42 GMT+03:00 H.J. Lu <hjl.tools@gmail.com>:
>> On Wed, Mar 18, 2015 at 7:31 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>>> On Wed, Mar 18, 2015 at 7:02 AM, Jakub Jelinek <jakub@redhat.com> wrote:
>>>>
>>>> Yeah, I agree, the configure check is a reasonable thing to do.
>>>>
>>>
>>> We should either always pass -z bndplt to linker or disable
>>> MPX.
>>>
>>
>> MPX is a security feature.  Knowing leaving a door open is a
>> bad idea.
>
> Instrumented binary used with legacy libraries is a supported usage
> model. Each user determines his own level of security.
>

It doesn't mean we should leave a door open.  Are we supposed to
detect this with MPX:

[hjl@skylakeclient bug-1]$ cat x.c
#include <string.h>

int
main ()
{
  char buf[10];
  memset(buf, 'a', 11);
  return 0;
}
[hjl@skylakeclient bug-1]$

I believe we should, not maybe.  We shouldn't silent fail it
when linker doesn't support -z bndplt.

-- 
H.J.