Re: [PATCH 08/12] De-PLTize __stack_chk_fail internal calls within libc.so.

[Florian Weimer <fweimer at redhat dot com>]

On 12/15/2016 03:15 PM, Nix wrote:

> Possible fix, untested:
>
> diff --git a/sysdeps/generic/symbol-hacks.h b/sysdeps/generic/symbol-hacks.h
> index 36908b5..0679354 100644
> --- a/sysdeps/generic/symbol-hacks.h
> +++ b/sysdeps/generic/symbol-hacks.h
> @@ -7,5 +7,7 @@ asm ("memcpy = __GI_memcpy");
>
>  /* -fstack-protector generates calls to __stack_chk_fail, which need
>     similar adjustments to avoid going through the PLT.  */
> +#if defined __SSP__ || defined __SSP_ALL__ || defined __SSP_STRONG__
>  asm ("__stack_chk_fail = __stack_chk_fail_local");
>  #endif
> +#endif

The condition looks rather brittle.  What if GCC grows an 
-fstack-protector-light switch and __SSP_LIGHT__ macro?

I wonder if it's better to add something to $(no-stack-protector) and 
use that in the conditional.

Thanks,
Florian