Re: [Qemu-trivial] [Qemu-devel] [PATCH v2 1/1] configure: use appropriate code fragment for -fstack-protector checks

[Markus Armbruster <armbru@redhat.com>]

Rodrigo Rebello <rprebello@gmail.com> writes:

> The check for stack-protector support consisted in compiling and linking
> the test program below (output by function write_c_skeleton()) with the
> compiler flag -fstack-protector-strong first and then with
> -fstack-protector-all if the first one failed to work:
>
>   int main(void) { return 0; }
>
> This caused false positives when using certain toolchains in which the
> compiler accepted -fstack-protector-strong but no support was provided
> by the C library, since for this stack-protector variant the compiler
> emits canary code only for functions that meet specific conditions
> (local arrays, memory references to local variables, etc.) and the code
> fragment under test included none of them (hence no stack protection
> code generated, no link failure).
>
> This fix changes the test program used for -fstack-protector checks to
> include a function that meets conditions which cause the compiler to
> generate canary code in all variants.
>
> Signed-off-by: Rodrigo Rebello <rprebello@gmail.com>

Reviewed-by: Markus Armbruster <armbru@redhat.com>