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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-08-04 13:38:35 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-08-04 13:38:35 -0700 |
| commit | 5b5d3be5d690a94be390ccf3e4db8dcb7409bf75 (patch) | |
| tree | 3a5a4981e702c4a7db1f74c7c5471db248d509fc /security | |
| parent | 3e4a12a1bafafecaf1631f02099e82b424967718 (diff) | |
| parent | f0fe00d4972a8cd4b98cc2c29758615e4d51cdfe (diff) | |
Merge tag 'var-init-v5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull automatic variable initialization updates from Kees Cook:
"This adds the "zero" init option from Clang, which is being used
widely in production builds of Android and Chrome OS (though it also
keeps the "pattern" init, which is better for debug builds).
- Introduce CONFIG_INIT_STACK_ALL_ZERO (Alexander Potapenko)"
* tag 'var-init-v5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
security: allow using Clang's zero initialization for stack variables
Diffstat (limited to 'security')
| -rw-r--r-- | security/Kconfig.hardening | 29 |
1 files changed, 25 insertions, 4 deletions
diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening index af4c979b38ee..269967c4fc1b 100644 --- a/security/Kconfig.hardening +++ b/security/Kconfig.hardening @@ -19,13 +19,16 @@ config GCC_PLUGIN_STRUCTLEAK menu "Memory initialization" -config CC_HAS_AUTO_VAR_INIT +config CC_HAS_AUTO_VAR_INIT_PATTERN def_bool $(cc-option,-ftrivial-auto-var-init=pattern) +config CC_HAS_AUTO_VAR_INIT_ZERO + def_bool $(cc-option,-ftrivial-auto-var-init=zero -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang) + choice prompt "Initialize kernel stack variables at function entry" default GCC_PLUGIN_STRUCTLEAK_BYREF_ALL if COMPILE_TEST && GCC_PLUGINS - default INIT_STACK_ALL if COMPILE_TEST && CC_HAS_AUTO_VAR_INIT + default INIT_STACK_ALL_PATTERN if COMPILE_TEST && CC_HAS_AUTO_VAR_INIT_PATTERN default INIT_STACK_NONE help This option enables initialization of stack variables at @@ -88,9 +91,9 @@ choice of uninitialized stack variable exploits and information exposures. - config INIT_STACK_ALL + config INIT_STACK_ALL_PATTERN bool "0xAA-init everything on the stack (strongest)" - depends on CC_HAS_AUTO_VAR_INIT + depends on CC_HAS_AUTO_VAR_INIT_PATTERN help Initializes everything on the stack with a 0xAA pattern. This is intended to eliminate all classes @@ -98,6 +101,24 @@ choice exposures, even variables that were warned to have been left uninitialized. + Pattern initialization is known to provoke many existing bugs + related to uninitialized locals, e.g. pointers receive + non-NULL values, buffer sizes and indices are very big. + + config INIT_STACK_ALL_ZERO + bool "zero-init everything on the stack (strongest and safest)" + depends on CC_HAS_AUTO_VAR_INIT_ZERO + help + Initializes everything on the stack with a zero + value. This is intended to eliminate all classes + of uninitialized stack variable exploits and information + exposures, even variables that were warned to have been + left uninitialized. + + Zero initialization provides safe defaults for strings, + pointers, indices and sizes, and is therefore + more suitable as a security mitigation measure. + endchoice config GCC_PLUGIN_STRUCTLEAK_VERBOSE |