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Date: Wed, 18 Mar 2015 17:13:00 -0000
Message-ID: <CAMbmDYZq8ww6Ot_EoRJ5oJCPppiRc-_F1DzwQY3i+b8R6qWaJQ@mail.gmail.com>
Subject: Re: [PATCH, libmpx, i386, PR driver/65444] Pass '-z bndplt' when building dynamic objects with MPX
From: Ilya Enkovich <enkovich.gnu@gmail.com>
To: "H.J. Lu" <hjl.tools@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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2015-03-18 19:45 GMT+03:00 H.J. Lu <hjl.tools@gmail.com>:
> 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:
>>>
>>> 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.

It depends on compiler flags and libraries used and is up to user to
decide. User may be warned during libmpx configuration.

Ilya

>
> --
> H.J.