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config HAVE_ARCH_KASAN
bool
if HAVE_ARCH_KASAN
config KASAN
bool "KASan: runtime memory debugger"
depends on (SLUB && SYSFS) || (SLAB && !DEBUG_SLAB)
select SLUB_DEBUG if SLUB
select CONSTRUCTORS
select STACKDEPOT
help
Enables kernel address sanitizer - runtime memory debugger,
designed to find out-of-bounds accesses and use-after-free bugs.
This is strictly a debugging feature and it requires a gcc version
of 4.9.2 or later. Detection of out of bounds accesses to stack or
global variables requires gcc 5.0 or later.
This feature consumes about 1/8 of available memory and brings about
~x3 performance slowdown.
For better error detection enable CONFIG_STACKTRACE.
Currently CONFIG_KASAN doesn't work with CONFIG_DEBUG_SLAB
(the resulting kernel does not boot).
config KASAN_EXTRA
bool "KAsan: extra checks"
depends on KASAN && DEBUG_KERNEL && !COMPILE_TEST
help
This enables further checks in the kernel address sanitizer, for now
it only includes the address-use-after-scope check that can lead
to excessive kernel stack usage, frame size warnings and longer
compile time.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715 has more
choice
prompt "Instrumentation type"
depends on KASAN
default KASAN_OUTLINE
config KASAN_OUTLINE
bool "Outline instrumentation"
help
Before every memory access compiler insert function call
__asan_load*/__asan_store*. These functions performs check
of shadow memory. This is slower than inline instrumentation,
however it doesn't bloat size of kernel's .text section so
much as inline does.
config KASAN_INLINE
bool "Inline instrumentation"
help
Compiler directly inserts code checking shadow memory before
memory accesses. This is faster than outline (in some workloads
it gives about x2 boost over outline instrumentation), but
make kernel's .text size much bigger.
This requires a gcc version of 5.0 or later.
endchoice
config KASAN_S390_4_LEVEL_PAGING
bool "KASan: use 4-level paging"
depends on KASAN && S390
help
Compiling the kernel with KASan disables automatic 3-level vs
4-level paging selection. 3-level paging is used by default (up
to 3TB of RAM with KASan enabled). This options allows to force
4-level paging instead.
config TEST_KASAN
tristate "Module for testing kasan for bug detection"
depends on m && KASAN
help
This is a test module doing various nasty things like
out of bounds accesses, use after free. It is useful for testing
kernel debugging features like kernel address sanitizer.
endif
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