[Buildroot] [PATCH 1/2] toolchain/external: copy libssp.so if SSP is enabled

[Romain Naour]

Hi Yann,

Le 09/09/2019 à 22:11, Yann Droneaud a écrit :
> Hi,
> 
> Le samedi 07 septembre 2019 à 15:18 +0200, Romain Naour a écrit :
> 
>>
> 
>> Thanks for your patch.
>>
>> Le 02/09/2019 à 08:37, Yann Droneaud a écrit :
>>> Unlike libgcc_s.so, libssp.so is not copied on the target file
>>> system. As it's available at link time, allowing packages such
>>> as sox to be linked against the library.
>>>
>>> As it's not copied, running programs linked against libssp.so
>>> lead to failure such as the following:
>>>
>>>   $ sox
>>>   sox: error while loading shared libraries: libssp.so.0: cannot
>>> open shared object file: No such file or directory
>>>
>>>   $ rec
>>>   rec: error while loading shared libraries: libssp.so.0: cannot
>>> open shared object file: No such file or directory
>>>
>>> If BR2_SSP_REGULAR, BR2_SSP_STRONG, or BR2_SSP_ALL is set, as
>>> libssp.so provides __stack_chk_fail, and *_chk symbols, the
>>> library must be copied to the target filesystem, like libgcc_s.so.
>>>
>>> If BR2_SSP_NONE is set, there should be no need to copy it.
>>
>> I'm unable to reproduce the issue with the following defconfig:
>>
>> BR2_aarch64=y
>> BR2_SSP_ALL=y
>> BR2_TOOLCHAIN_EXTERNAL=y
>> BR2_TARGET_GENERIC_GETTY_PORT="ttyAMA0"
>> BR2_SYSTEM_DHCP="eth0"
>> BR2_LINUX_KERNEL=y
>> BR2_LINUX_KERNEL_CUSTOM_VERSION=y
>> BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="4.19.16"
>> BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
>> BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="board/qemu/aarch64-
>> virt/linux.config"
>> BR2_LINUX_KERNEL_NEEDS_HOST_OPENSSL=y
>> BR2_PACKAGE_SOX=y
>> BR2_TARGET_ROOTFS_EXT2=y
>> BR2_TARGET_ROOTFS_EXT2_4=y
>> # BR2_TARGET_ROOTFS_TAR is not set
>>
>> This defconfig use the external toolchain from ARM that provide SSP
>> support.
>> But there is no libssp.so in this toolchain.
>>
>> Also, libssp from gcc is disabled in Buildroot for internal toolchain
>> since a while:
>> https://git.buildroot.net/buildroot/commit/?id=3b712a3d891bf23055a587fc518f7cd2139a6a09
>>
>> In Buildroot, we are using libssp provided by the C library (glibc,
>> musl, uClibc-ng) when available. We are not using libssp from gcc.
>>
>> Can you describe your issue ? Are you using a custom external
>> toolchain ?
>>
> 
> I'm sorry I wasn't specific enough. I had the issue with linaro aarch64
> external toolchain. (For some reason I don't recall, I thought this
> issue happen with other toolchain, but it's doesn't happen with ARM one
> as you demonstrated, nor with Codesourcery one).

No problem at all!

Actually the toolchain have both ssp implementation: libssp from gcc and ssp
from Glibc!

ssp_cv_cc=yes
ssp_cv_lib=yes

I did a second build and removed libssp* files after extracting the toolchain
and sox is able to detect the ssp support from Glibc.

ssp_cv_cc=yes
ssp_cv_lib=no

Note: the ssp test from helpers.mk [1] only test without -lssp.
You can find additional information here [2].

So, you can patch sox to prefer the libc's ssp implementation and/or remove
those libssp libraries from a POST_EXTRACT_HOOKS in the
toolchain-external-linaro-aarch64 package.

[1]
https://git.buildroot.net/buildroot/tree/toolchain/helpers.mk?id=03fb00f2175cdb4565e26fcb9b3da1c1059de1bd#n424
[2] https://patchwork.openembedded.org/patch/150197/

Best regards,
Romain

> 
> Regards.
>