[PATCH v2] use -fstack-protector-strong

[Kees Cook]

On Wed, Nov 27, 2013 at 10:11 AM, Kees Cook <keescook at chromium.org> wrote:
> On Wed, Nov 27, 2013 at 9:55 AM, H. Peter Anvin <hpa at zytor.com> wrote:
>> On 11/27/2013 09:54 AM, Ingo Molnar wrote:
>>>>
>>>> Looks to be 2% for defconfig. That's way better. Shall I send a v3?
>>>
>>> Well, it's better than 9%, but still almost an order of magnitude
>>> higher than the cost is today, and a lot of distros have
>>> CONFIG_CC_STACKPROTECTOR=y.
>>>
>>> So it would be nice to measure how much the instruction count goes up
>>> in some realistic system-bound test. How much does something like
>>> kernel/built-in.o increase, as per 'size' output?
>
>    text    data     bss     dec     hex filename
>  929611   90851  594496 1614958  18a46e built-in.o-gcc-4.9
>  954648   90851  594496 1639995  19063b built-in.o-gcc-4.9+strong
>
> Looks like 3% for defconfg + CONFIG_CC_STACKPROTECTOR
>
>>
>> Do we need CONFIG_CC_STACKPROTECTOR_STRONG?
>
> I'm hoping to avoid this since nearly anyone using CC_STACKPROTECTOR
> would want strong added, but as a fallback, I'm happy to implement it
> as a separate config item.

Any verdict on this? Should I go with adding ..._STRONG like we used
to have for ..._ALL, or is defaulting to -strong best?

-Kees

-- 
Kees Cook
Chrome OS Security