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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2018-06-14 06:21:18 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-06-14 06:21:18 +0300 |
| commit | 050e9baa9dc9fbd9ce2b27f0056990fc9e0a08a0 (patch) | |
| tree | 5087d180ea4c26c6b89f10bc160c15559cc02785 /arch/Kconfig | |
| parent | be779f03d563981c65cc7417cc5e0dbbc5b89d30 (diff) | |
| download | linux-050e9baa9dc9fbd9ce2b27f0056990fc9e0a08a0.tar.xz | |
Kbuild: rename CC_STACKPROTECTOR[_STRONG] config variables
The changes to automatically test for working stack protector compiler
support in the Kconfig files removed the special STACKPROTECTOR_AUTO
option that picked the strongest stack protector that the compiler
supported.
That was all a nice cleanup - it makes no sense to have the AUTO case
now that the Kconfig phase can just determine the compiler support
directly.
HOWEVER.
It also meant that doing "make oldconfig" would now _disable_ the strong
stackprotector if you had AUTO enabled, because in a legacy config file,
the sane stack protector configuration would look like
CONFIG_HAVE_CC_STACKPROTECTOR=y
# CONFIG_CC_STACKPROTECTOR_NONE is not set
# CONFIG_CC_STACKPROTECTOR_REGULAR is not set
# CONFIG_CC_STACKPROTECTOR_STRONG is not set
CONFIG_CC_STACKPROTECTOR_AUTO=y
and when you ran this through "make oldconfig" with the Kbuild changes,
it would ask you about the regular CONFIG_CC_STACKPROTECTOR (that had
been renamed from CONFIG_CC_STACKPROTECTOR_REGULAR to just
CONFIG_CC_STACKPROTECTOR), but it would think that the STRONG version
used to be disabled (because it was really enabled by AUTO), and would
disable it in the new config, resulting in:
CONFIG_HAVE_CC_STACKPROTECTOR=y
CONFIG_CC_HAS_STACKPROTECTOR_NONE=y
CONFIG_CC_STACKPROTECTOR=y
# CONFIG_CC_STACKPROTECTOR_STRONG is not set
CONFIG_CC_HAS_SANE_STACKPROTECTOR=y
That's dangerously subtle - people could suddenly find themselves with
the weaker stack protector setup without even realizing.
The solution here is to just rename not just the old RECULAR stack
protector option, but also the strong one. This does that by just
removing the CC_ prefix entirely for the user choices, because it really
is not about the compiler support (the compiler support now instead
automatially impacts _visibility_ of the options to users).
This results in "make oldconfig" actually asking the user for their
choice, so that we don't have any silent subtle security model changes.
The end result would generally look like this:
CONFIG_HAVE_CC_STACKPROTECTOR=y
CONFIG_CC_HAS_STACKPROTECTOR_NONE=y
CONFIG_STACKPROTECTOR=y
CONFIG_STACKPROTECTOR_STRONG=y
CONFIG_CC_HAS_SANE_STACKPROTECTOR=y
where the "CC_" versions really are about internal compiler
infrastructure, not the user selections.
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/Kconfig')
| -rw-r--r-- | arch/Kconfig | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/Kconfig b/arch/Kconfig index ebbb45096191..c302b3dd0058 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -558,7 +558,7 @@ config HAVE_CC_STACKPROTECTOR config CC_HAS_STACKPROTECTOR_NONE def_bool $(cc-option,-fno-stack-protector) -config CC_STACKPROTECTOR +config STACKPROTECTOR bool "Stack Protector buffer overflow detection" depends on HAVE_CC_STACKPROTECTOR depends on $(cc-option,-fstack-protector) @@ -582,9 +582,9 @@ config CC_STACKPROTECTOR about 3% of all kernel functions, which increases kernel code size by about 0.3%. -config CC_STACKPROTECTOR_STRONG +config STACKPROTECTOR_STRONG bool "Strong Stack Protector" - depends on CC_STACKPROTECTOR + depends on STACKPROTECTOR depends on $(cc-option,-fstack-protector-strong) default y help |