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 !COMPILE_TEST
  18         depends on $(cc-option, -fsanitize-undefined-trap-on-error)
  19         help
  20           Building kernels with Sanitizer features enabled tends to grow
  21           the kernel size by around 5%, due to adding all the debugging
  22           text on failure paths. To avoid this, Sanitizer instrumentation
  23           can just issue a trap. This reduces the kernel size overhead but
  24           turns all warnings (including potentially harmless conditions)
  25           into full exceptions that abort the running kernel code
  26           (regardless of context, locks held, etc), which may destabilize
  27           the system. For some system builders this is an acceptable
  28           trade-off.
  29
  30 config UBSAN_KCOV_BROKEN
  31         def_bool KCOV && CC_HAS_SANCOV_TRACE_PC
  32         depends on CC_IS_CLANG
  33         depends on !$(cc-option,-Werror=unused-command-line-argument -fsanitize=bounds -fsanitize-coverage=trace-pc)
  34         help
  35           Some versions of clang support either UBSAN or KCOV but not the
  36           combination of the two.
  37           See https://bugs.llvm.org/show_bug.cgi?id=45831 for the status
  38           in newer releases.
  39
  40 config CC_HAS_UBSAN_BOUNDS
  41         def_bool $(cc-option,-fsanitize=bounds)
  42
  43 config CC_HAS_UBSAN_ARRAY_BOUNDS
  44         def_bool $(cc-option,-fsanitize=array-bounds)
  45
  46 config UBSAN_BOUNDS
  47         bool "Perform array index bounds checking"
  48         default UBSAN
  49         depends on !UBSAN_KCOV_BROKEN
  50         depends on CC_HAS_UBSAN_ARRAY_BOUNDS || CC_HAS_UBSAN_BOUNDS
  51         help
  52           This option enables detection of directly indexed out of bounds
  53           array accesses, where the array size is known at compile time.
  54           Note that this does not protect array overflows via bad calls
  55           to the {str,mem}*cpy() family of functions (that is addressed
  56           by CONFIG_FORTIFY_SOURCE).
  57
  58 config UBSAN_ONLY_BOUNDS
  59         def_bool CC_HAS_UBSAN_BOUNDS && !CC_HAS_UBSAN_ARRAY_BOUNDS
  60         depends on UBSAN_BOUNDS
  61         help
  62           This is a weird case: Clang's -fsanitize=bounds includes
  63           -fsanitize=local-bounds, but it's trapping-only, so for
  64           Clang, we must use -fsanitize=array-bounds when we want
  65           traditional array bounds checking enabled. For GCC, we
  66           want -fsanitize=bounds.
  67
  68 config UBSAN_ARRAY_BOUNDS
  69         def_bool CC_HAS_UBSAN_ARRAY_BOUNDS
  70         depends on UBSAN_BOUNDS
  71
  72 config UBSAN_LOCAL_BOUNDS
  73         bool "Perform array local bounds checking"
  74         depends on UBSAN_TRAP
  75         depends on !UBSAN_KCOV_BROKEN
  76         depends on $(cc-option,-fsanitize=local-bounds)
  77         help
  78           This option enables -fsanitize=local-bounds which traps when an
  79           exception/error is detected. Therefore, it may only be enabled
  80           with CONFIG_UBSAN_TRAP.
  81
  82           Enabling this option detects errors due to accesses through a
  83           pointer that is derived from an object of a statically-known size,
  84           where an added offset (which may not be known statically) is
  85           out-of-bounds.
  86
  87 config UBSAN_SHIFT
  88         bool "Perform checking for bit-shift overflows"
  89         default UBSAN
  90         depends on $(cc-option,-fsanitize=shift)
  91         help
  92           This option enables -fsanitize=shift which checks for bit-shift
  93           operations that overflow to the left or go switch to negative
  94           for signed types.
  95
  96 config UBSAN_DIV_ZERO
  97         bool "Perform checking for integer divide-by-zero"
  98         depends on $(cc-option,-fsanitize=integer-divide-by-zero)
  99         help
 100           This option enables -fsanitize=integer-divide-by-zero which checks
 101           for integer division by zero. This is effectively redundant with the
 102           kernel's existing exception handling, though it can provide greater
 103           debugging information under CONFIG_UBSAN_REPORT_FULL.
 104
 105 config UBSAN_UNREACHABLE
 106         bool "Perform checking for unreachable code"
 107         # objtool already handles unreachable checking and gets angry about
 108         # seeing UBSan instrumentation located in unreachable places.
 109         depends on !STACK_VALIDATION
 110         depends on $(cc-option,-fsanitize=unreachable)
 111         help
 112           This option enables -fsanitize=unreachable which checks for control
 113           flow reaching an expected-to-be-unreachable position.
 114
 115 config UBSAN_SIGNED_OVERFLOW
 116         bool "Perform checking for signed arithmetic overflow"
 117         default UBSAN
 118         depends on $(cc-option,-fsanitize=signed-integer-overflow)
 119         help
 120           This option enables -fsanitize=signed-integer-overflow which checks
 121           for overflow of any arithmetic operations with signed integers.
 122
 123 config UBSAN_UNSIGNED_OVERFLOW
 124         bool "Perform checking for unsigned arithmetic overflow"
 125         depends on $(cc-option,-fsanitize=unsigned-integer-overflow)
 126         depends on !X86_32 # avoid excessive stack usage on x86-32/clang
 127         help
 128           This option enables -fsanitize=unsigned-integer-overflow which checks
 129           for overflow of any arithmetic operations with unsigned integers. This
 130           currently causes x86 to fail to boot.
 131
 132 config UBSAN_OBJECT_SIZE
 133         bool "Perform checking for accesses beyond the end of objects"
 134         default UBSAN
 135         # gcc hugely expands stack usage with -fsanitize=object-size
 136         # https://lore.kernel.org/lkml/CAHk-=wjPasyJrDuwDnpHJS2TuQfExwe=px-SzLeN8GFMAQJPmQ@mail.gmail.com/
 137         depends on !CC_IS_GCC
 138         depends on $(cc-option,-fsanitize=object-size)
 139         help
 140           This option enables -fsanitize=object-size which checks for accesses
 141           beyond the end of objects where the optimizer can determine both the
 142           object being operated on and its size, usually seen with bad downcasts,
 143           or access to struct members from NULL pointers.
 144
 145 config UBSAN_BOOL
 146         bool "Perform checking for non-boolean values used as boolean"
 147         default UBSAN
 148         depends on $(cc-option,-fsanitize=bool)
 149         help
 150           This option enables -fsanitize=bool which checks for boolean values being
 151           loaded that are neither 0 nor 1.
 152
 153 config UBSAN_ENUM
 154         bool "Perform checking for out of bounds enum values"
 155         default UBSAN
 156         depends on $(cc-option,-fsanitize=enum)
 157         help
 158           This option enables -fsanitize=enum which checks for values being loaded
 159           into an enum that are outside the range of given values for the given enum.
 160
 161 config UBSAN_ALIGNMENT
 162         bool "Perform checking for misaligned pointer usage"
 163         default !HAVE_EFFICIENT_UNALIGNED_ACCESS
 164         depends on !UBSAN_TRAP && !COMPILE_TEST
 165         depends on $(cc-option,-fsanitize=alignment)
 166         help
 167           This option enables the check of unaligned memory accesses.
 168           Enabling this option on architectures that support unaligned
 169           accesses may produce a lot of false positives.
 170
 171 config UBSAN_SANITIZE_ALL
 172         bool "Enable instrumentation for the entire kernel"
 173         depends on ARCH_HAS_UBSAN_SANITIZE_ALL
 174         default y
 175         help
 176           This option activates instrumentation for the entire kernel.
 177           If you don't enable this option, you have to explicitly specify
 178           UBSAN_SANITIZE := y for the files/directories you want to check for UB.
 179           Enabling this option will get kernel image size increased
 180           significantly.
 181
 182 config TEST_UBSAN
 183         tristate "Module for testing for undefined behavior detection"
 184         depends on m
 185         help
 186           This is a test module for UBSAN.
 187           It triggers various undefined behavior, and detect it.
 188
 189 endif   # if UBSAN