lib/Kconfig.ubsan

   1 # SPDX-License-Identifier: GPL-2.0-only
   2 config ARCH_HAS_UBSAN_SANITIZE_ALL
   3         bool
   4
   5 menuconfig UBSAN
   6         bool "Undefined behaviour sanity checker"
   7         help
   8           This option enables the Undefined Behaviour sanity checker.
   9           Compile-time instrumentation is used to detect various undefined
  10           behaviours at runtime. For more details, see:
  11           Documentation/dev-tools/ubsan.rst
  12
  13 if UBSAN
  14
  15 config UBSAN_TRAP
  16         bool "On Sanitizer warnings, abort the running kernel code"
  17         depends on $(cc-option, -fsanitize-undefined-trap-on-error)
  18         help
  19           Building kernels with Sanitizer features enabled tends to grow
  20           the kernel size by around 5%, due to adding all the debugging
  21           text on failure paths. To avoid this, Sanitizer instrumentation
  22           can just issue a trap. This reduces the kernel size overhead but
  23           turns all warnings (including potentially harmless conditions)
  24           into full exceptions that abort the running kernel code
  25           (regardless of context, locks held, etc), which may destabilize
  26           the system. For some system builders this is an acceptable
  27           trade-off.
  28
  29 config UBSAN_KCOV_BROKEN
  30         def_bool KCOV && CC_HAS_SANCOV_TRACE_PC
  31         depends on CC_IS_CLANG
  32         depends on !$(cc-option,-Werror=unused-command-line-argument -fsanitize=bounds -fsanitize-coverage=trace-pc)
  33         help
  34           Some versions of clang support either UBSAN or KCOV but not the
  35           combination of the two.
  36           See https://bugs.llvm.org/show_bug.cgi?id=45831 for the status
  37           in newer releases.
  38
  39 config UBSAN_BOUNDS
  40         bool "Perform array index bounds checking"
  41         default UBSAN
  42         depends on !UBSAN_KCOV_BROKEN
  43         help
  44           This option enables detection of directly indexed out of bounds
  45           array accesses, where the array size is known at compile time.
  46           Note that this does not protect array overflows via bad calls
  47           to the {str,mem}*cpy() family of functions (that is addressed
  48           by CONFIG_FORTIFY_SOURCE).
  49
  50 config UBSAN_LOCAL_BOUNDS
  51         bool "Perform array local bounds checking"
  52         depends on UBSAN_TRAP
  53         depends on CC_IS_CLANG
  54         depends on !UBSAN_KCOV_BROKEN
  55         help
  56           This option enables -fsanitize=local-bounds which traps when an
  57           exception/error is detected. Therefore, it should be enabled only
  58           if trapping is expected.
  59           Enabling this option detects errors due to accesses through a
  60           pointer that is derived from an object of a statically-known size,
  61           where an added offset (which may not be known statically) is
  62           out-of-bounds.
  63
  64 config UBSAN_MISC
  65         bool "Enable all other Undefined Behavior sanity checks"
  66         default UBSAN
  67         help
  68           This option enables all sanity checks that don't have their
  69           own Kconfig options. Disable this if you only want to have
  70           individually selected checks.
  71
  72 config UBSAN_SANITIZE_ALL
  73         bool "Enable instrumentation for the entire kernel"
  74         depends on ARCH_HAS_UBSAN_SANITIZE_ALL
  75
  76         # We build with -Wno-maybe-uninitilzed, but we still want to
  77         # use -Wmaybe-uninitilized in allmodconfig builds.
  78         # So dependsy bellow used to disable this option in allmodconfig
  79         depends on !COMPILE_TEST
  80         default y
  81         help
  82           This option activates instrumentation for the entire kernel.
  83           If you don't enable this option, you have to explicitly specify
  84           UBSAN_SANITIZE := y for the files/directories you want to check for UB.
  85           Enabling this option will get kernel image size increased
  86           significantly.
  87
  88 config UBSAN_ALIGNMENT
  89         bool "Enable checks for pointers alignment"
  90         default !HAVE_EFFICIENT_UNALIGNED_ACCESS
  91         depends on !UBSAN_TRAP
  92         help
  93           This option enables the check of unaligned memory accesses.
  94           Enabling this option on architectures that support unaligned
  95           accesses may produce a lot of false positives.
  96
  97 config TEST_UBSAN
  98         tristate "Module for testing for undefined behavior detection"
  99         depends on m
 100         help
 101           This is a test module for UBSAN.
 102           It triggers various undefined behavior, and detect it.
 103
 104 endif   # if UBSAN