Kernel stack smashing protection on x86_64

For Developers
1

Anyone able to tell me why kernel stack smashing protection is disabled on x86_64 when using glibc?

        choice
                prompt "Kernel space Stack-Smashing Protection"
                default KERNEL_CC_STACKPROTECTOR_REGULAR
                depends on USE_MUSL || !(x86_64 || i386)
                help
                  Enable GCC Stack-Smashing Protection (SSP) for the kernel
                config KERNEL_CC_STACKPROTECTOR_NONE
                        bool "None"
                config KERNEL_CC_STACKPROTECTOR_REGULAR
                        bool "Regular"
                config KERNEL_CC_STACKPROTECTOR_STRONG
                        bool "Strong"
        endchoice
2

You an use git blame to find the commit hash that affect that line and then you can find the commit message that should provide enough information about the reasoning.

3

Thanks @fantom-x

Here's the reason if anyone else is looking for the same info

commit bf82deff7069599c9f130f5bb0222acd171fd19d
Author: Felix Fietkau <nbd@openwrt.org>
Date:   Sun Aug 2 07:40:12 2015 +0000

    build: disable kernel stack protector support for i386/x86_64
    
    When stack protector support is disabled in libc (always the case for
    !musl), gcc assumes that it needs to use __stack_chk_guard for the stack
    canary.
    This causes kernel build errors, because the kernel is only set up to
    handle TLS stack canaries.
    
    Signed-off-by: Felix Fietkau <nbd@openwrt.org>
    
    SVN-Revision: 46543