[Buildroot] [PATCH]Libssp support

[Arnout Vandecappelle]

 Hi Guy,

 [Please don't top-post, but reply in-line, like I do now.]

On 11-06-17 10:55, Guy Benyei wrote:
> Hi Thomas,
> I checked the issue, and here are my findings:
> Libssp is used by gcc, only when the gcc_cv_libc_provides_ssp gcc configuration flag is set to "no".  In buildroot, this flag is set as:
> 
> 	HOST_GCC_COMMON_MAKE_OPTS = \
> 		gcc_cv_libc_provides_ssp=$(if $(BR2_TOOLCHAIN_HAS_SSP),yes,no)
> 
> For glibc SSP support is enabled by default, and BR2_TOOLCHAIN_HAS_SSP is set. Same goes for musl, except for some specific architectures. uClibc sets BR2_TOOLCHAIN_HAS_SSP only is it's configured to support SSP.

> All in all, it only makes sense to build and install libssp if the C library
> doesn't support SSP, i.e.: BR2_TOOLCHAIN_HAS_SSP is set to "n".

 It's a little more complicated than that - BR2_TOOLCHAIN_HAS_SSP should be set
when -fstack-protector works with this toolchain. In other words, if you make a
patch that uses gcc's libssp, then this symbol should be selected.

 So you need to introduce a new symbol (e.g. BR2_LIBC_HAS_SSP) that is set by
the libc, and use gcc's libssp if it is not set. The internal toolchain should
then always set BR2_TOOLCHAIN_HAS_SSP.

 All in all, a fairly complicated patch, I'm afraid. When you post something
we'll provice feedback on how it should be improved.

 Regards,
 Arnout

> I'll send out an updated patch soon.



-- 
Arnout Vandecappelle                          arnout at mind be
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