lib/Kconfig.kasan

   1 config HAVE_ARCH_KASAN
   2         bool
   3
   4 if HAVE_ARCH_KASAN
   5
   6 config KASAN
   7         bool "KASan: runtime memory debugger"
   8         depends on SLUB || (SLAB && !DEBUG_SLAB)
   9         select CONSTRUCTORS
  10         select STACKDEPOT
  11         help
  12           Enables kernel address sanitizer - runtime memory debugger,
  13           designed to find out-of-bounds accesses and use-after-free bugs.
  14           This is strictly a debugging feature and it requires a gcc version
  15           of 4.9.2 or later. Detection of out of bounds accesses to stack or
  16           global variables requires gcc 5.0 or later.
  17           This feature consumes about 1/8 of available memory and brings about
  18           ~x3 performance slowdown.
  19           For better error detection enable CONFIG_STACKTRACE.
  20           Currently CONFIG_KASAN doesn't work with CONFIG_DEBUG_SLAB
  21           (the resulting kernel does not boot).
  22
  23 config KASAN_EXTRA
  24         bool "KAsan: extra checks"
  25         depends on KASAN && DEBUG_KERNEL && !COMPILE_TEST
  26         help
  27           This enables further checks in the kernel address sanitizer, for now
  28           it only includes the address-use-after-scope check that can lead
  29           to excessive kernel stack usage, frame size warnings and longer
  30           compile time.
  31           https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715 has more
  32
  33
  34 choice
  35         prompt "Instrumentation type"
  36         depends on KASAN
  37         default KASAN_OUTLINE
  38
  39 config KASAN_OUTLINE
  40         bool "Outline instrumentation"
  41         help
  42           Before every memory access compiler insert function call
  43           __asan_load*/__asan_store*. These functions performs check
  44           of shadow memory. This is slower than inline instrumentation,
  45           however it doesn't bloat size of kernel's .text section so
  46           much as inline does.
  47
  48 config KASAN_INLINE
  49         bool "Inline instrumentation"
  50         help
  51           Compiler directly inserts code checking shadow memory before
  52           memory accesses. This is faster than outline (in some workloads
  53           it gives about x2 boost over outline instrumentation), but
  54           make kernel's .text size much bigger.
  55           This requires a gcc version of 5.0 or later.
  56
  57 endchoice
  58
  59 config TEST_KASAN
  60         tristate "Module for testing kasan for bug detection"
  61         depends on m && KASAN
  62         help
  63           This is a test module doing various nasty things like
  64           out of bounds accesses, use after free. It is useful for testing
  65           kernel debugging features like kernel address sanitizer.
  66
  67 endif