[Buildroot] [PATCH] Config.in: disable PIC/PIE for Nios2

[Arnout Vandecappelle]

On 01/06/2021 21:00, Romain Naour wrote:
> Recently in Buildroot the option BR2_PIC_PIE has been enabled by default along
> with other hardening features [1]. Since then the nios2 defconfig
> qemu_nios2_10m50_defconfig is failing to boot due to a segfault in init program:
> 
> Run /init as init process
>   with arguments:
>     /init
>   with environment:
>     HOME=/
>     TERM=linux
> Failed to execute /init (error -12)
> 
> See Buildroot build log and Qemu runtime test log in build artifacts [2].
> 
> Analyzing one of the binary with strace show that the problem occur
> very early when starting the new process:
> 
>  # strace ./busybox
>  execve("./busybox", ["./busybox"], 0x7f91ce90 /* 10 vars */) = -1 ENOMEM
> (Cannot allocate memory)
>  +++ killed by SIGSEGV +++
> 
> Several binutils/glibc/gcc version has been tested without any success.
> 
> The issue has been reported to the glibc mailing list but it can be a linker
> or kernel bug [3].
> 
> For the Buildroot 2021.05 release, disable BR2_PIC_PIE until the problem is
> found and fixed.
> 
> Fixes:
> https://gitlab.com/buildroot.org/buildroot/-/jobs/1285145889
> 
> [1] https://git.buildroot.net/buildroot/commit/?id=810ba387bec3c5b6904e8893fb4cb6f9d3717466
> [2] https://gitlab.com/buildroot.org/buildroot/-/jobs/1285145889
> [3] https://sourceware.org/pipermail/libc-alpha/2021-May/126912.html
> 
> Signed-off-by: Romain Naour <romain.naour at gmail.com>
> Cc: Yann E. MORIN <yann.morin.1998 at free.fr>

 Applied to master, thanks.

 Regards,
 Arnout

> ---
>  Config.in | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/Config.in b/Config.in
> index c65e34bd5e..d9be677c21 100644
> --- a/Config.in
> +++ b/Config.in
> @@ -716,6 +716,8 @@ comment "Security Hardening Options"
>  config BR2_PIC_PIE
>  	bool "Build code with PIC/PIE"
>  	default y
> +	# Nios2 toolchains produce non working binaries with -fPIC
> +	depends on !BR2_nios2
>  	depends on BR2_SHARED_LIBS
>  	depends on BR2_TOOLCHAIN_SUPPORTS_PIE
>  	help
> @@ -723,6 +725,7 @@ config BR2_PIC_PIE
>  	  Position-Independent Executables (PIE).
>  
>  comment "PIC/PIE needs a toolchain w/ PIE"
> +	depends on !BR2_nios2
>  	depends on BR2_SHARED_LIBS
>  	depends on !BR2_TOOLCHAIN_SUPPORTS_PIE
>  
> @@ -813,6 +816,7 @@ config BR2_RELRO_PARTIAL
>  
>  config BR2_RELRO_FULL
>  	bool "Full"
> +	depends on !BR2_nios2 # BR2_PIC_PIE
>  	depends on BR2_TOOLCHAIN_SUPPORTS_PIE
>  	select BR2_PIC_PIE
>  	help
> @@ -821,6 +825,7 @@ config BR2_RELRO_FULL
>  	  program loading, i.e every time an executable is started.
>  
>  comment "RELRO Full needs a toolchain w/ PIE"
> +	depends on !BR2_nios2
>  	depends on !BR2_TOOLCHAIN_SUPPORTS_PIE
>  
>  endchoice
>