[Buildroot] [PATCH next] tpm2-abrmd: fix build without stack smashing protection (SSP)

[Carlos Santos <casantos@datacom.com.br>]

> From: "Thomas Petazzoni" <thomas.petazzoni@bootlin.com>
> To: "DATACOM" <casantos@datacom.com.br>
> Cc: "buildroot" <buildroot@buildroot.org>
> Sent: Quarta-feira, 21 de novembro de 2018 18:06:52
> Subject: Re: [Buildroot] [PATCH next] tpm2-abrmd: fix build without stack smashing protection (SSP)

> Hello,
> 
> On Wed, 21 Nov 2018 15:43:37 -0200, Carlos Santos wrote:
>> The configuration environment setup that disables SSP if the toolchain
>> does not support it must be updated after the bump to version 2.0.3.
>> 
>> Fixes:
>>   http://autobuild.buildroot.net/results/bd9005eeb24678aa530179a80bbc99b2176f8559
>>   http://autobuild.buildroot.net/results/feff61dcb481a94f5f030117830984c5e09727ea
>> 
>> Signed-off-by: Carlos Santos <casantos@datacom.com.br>
>> ---
>>  package/tpm2-abrmd/tpm2-abrmd.mk | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/package/tpm2-abrmd/tpm2-abrmd.mk b/package/tpm2-abrmd/tpm2-abrmd.mk
>> index a4d9cfb384..74cc66ba20 100644
>> --- a/package/tpm2-abrmd/tpm2-abrmd.mk
>> +++ b/package/tpm2-abrmd/tpm2-abrmd.mk
>> @@ -13,7 +13,7 @@ TPM2_ABRMD_DEPENDENCIES = dbus libglib2 tpm2-tss host-pkgconf
>>  
>>  # configure.ac doesn't contain a link test, so it doesn't detect when
>>  # libssp is missing.
>> -TPM2_ABRMD_CONF_ENV = ax_cv_check_cflags___fstack_protector_all=$(if
>> $(BR2_TOOLCHAIN_HAS_SSP),yes,no)
>> +TPM2_ABRMD_CONF_ENV =
>> ax_cv_check_cflags___________Werror_______fstack_protector_all=$(if
>> $(BR2_TOOLCHAIN_HAS_SSP),yes,no)
> 
> It's a bit annoying to fix this once in a while, what about the
> following change instead:
> 
> diff --git a/m4/flags.m4 b/m4/flags.m4
> index 1b01198..59b6d5b 100644
> --- a/m4/flags.m4
> +++ b/m4/flags.m4
> @@ -5,7 +5,7 @@ dnl   mandatory (configure will fail).
> dnl $1: C compiler flag to add to EXTRA_CFLAGS.
> dnl $2: Set to "required" to cause configure failure if flag not supported..
> AC_DEFUN([AX_ADD_COMPILER_FLAG],[
> -    AX_CHECK_COMPILE_FLAG([$1],[
> +    AX_CHECK_LINK_FLAG([$1],[
>         EXTRA_CFLAGS="$EXTRA_CFLAGS $1"
>         AC_SUBST([EXTRA_CFLAGS])],[
>         AS_IF([test x$2 != xrequired],[
> 
> (entirely untested). It could be submitted upstream.

I can forward your suggestion upstream but for the moment I'd keep
the CONF_ENV approach.

Patching flags.m4 would require AUTORECONF, which in its turn would
require adding host-autoconf-archive as a build dependency. So more
dependencies, a larger build to time and exactly the same result.

-- 
Carlos Santos (Casantos) - DATACOM, P&D
?Marched towards the enemy, spear upright, armed with the certainty
that only the ignorant can have.? ? Epitaph of a volunteer