|author||Kees Cook <email@example.com>||2018-02-06 15:37:45 -0800|
|committer||Linus Torvalds <firstname.lastname@example.org>||2018-02-06 18:32:44 -0800|
|parent||Makefile: move stack-protector availability out of Kconfig (diff)|
Makefile: introduce CONFIG_CC_STACKPROTECTOR_AUTO
Nearly all modern compilers support a stack-protector option, and nearly all modern distributions enable the kernel stack-protector, so enabling this by default in kernel builds would make sense. However, Kconfig does not have knowledge of available compiler features, so it isn't safe to force on, as this would unconditionally break builds for the compilers or architectures that don't have support. Instead, this introduces a new option, CONFIG_CC_STACKPROTECTOR_AUTO, which attempts to discover the best possible stack-protector available, and will allow builds to proceed even if the compiler doesn't support any stack-protector. This option is made the default so that kernels built with modern compilers will be protected-by-default against stack buffer overflows, avoiding things like the recent BlueBorne attack. Selection of a specific stack-protector option remains available, including disabling it. Additionally, tiny.config is adjusted to use CC_STACKPROTECTOR_NONE, since that's the option with the least code size (and it used to be the default, so we have to explicitly choose it there now). Link: http://email@example.com Signed-off-by: Kees Cook <firstname.lastname@example.org> Tested-by: Laura Abbott <email@example.com> Cc: Masahiro Yamada <firstname.lastname@example.org> Cc: Arnd Bergmann <email@example.com> Cc: Josh Triplett <firstname.lastname@example.org> Signed-off-by: Andrew Morton <email@example.com> Signed-off-by: Linus Torvalds <firstname.lastname@example.org>
Diffstat (limited to 'arch/Kconfig')
1 files changed, 7 insertions, 1 deletions
diff --git a/arch/Kconfig b/arch/Kconfig
index 9330a9d79dc3..76c0b54443b1 100644
@@ -541,7 +541,7 @@ config HAVE_CC_STACKPROTECTOR
prompt "Stack Protector buffer overflow detection"
depends on HAVE_CC_STACKPROTECTOR
- default CC_STACKPROTECTOR_NONE
+ default CC_STACKPROTECTOR_AUTO
This option turns on the "stack-protector" GCC feature. This
feature puts, at the beginning of functions, a canary value on
@@ -588,6 +588,12 @@ config CC_STACKPROTECTOR_STRONG
about 20% of all kernel functions, which increases the kernel code
size by about 2%.
+ bool "Automatic"
+ If the compiler supports it, the best available stack-protector
+ option will be chosen.