1# SPDX-License-Identifier: GPL-2.0-only 2config ARCH_HAS_UBSAN_SANITIZE_ALL 3 bool 4 5menuconfig 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 13if UBSAN 14 15config UBSAN_TRAP 16 bool "Abort on Sanitizer warnings (smaller kernel but less verbose)" 17 depends on !COMPILE_TEST 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 Also note that selecting Y will cause your kernel to Oops 30 with an "illegal instruction" error with no further details 31 when a UBSAN violation occurs. (Except on arm64 and x86, which 32 will report which Sanitizer failed.) This may make it hard to 33 determine whether an Oops was caused by UBSAN or to figure 34 out the details of a UBSAN violation. It makes the kernel log 35 output less useful for bug reports. 36 37config CC_HAS_UBSAN_BOUNDS_STRICT 38 def_bool $(cc-option,-fsanitize=bounds-strict) 39 help 40 The -fsanitize=bounds-strict option is only available on GCC, 41 but uses the more strict handling of arrays that includes knowledge 42 of flexible arrays, which is comparable to Clang's regular 43 -fsanitize=bounds. 44 45config CC_HAS_UBSAN_ARRAY_BOUNDS 46 def_bool $(cc-option,-fsanitize=array-bounds) 47 help 48 Under Clang, the -fsanitize=bounds option is actually composed 49 of two more specific options, -fsanitize=array-bounds and 50 -fsanitize=local-bounds. However, -fsanitize=local-bounds can 51 only be used when trap mode is enabled. (See also the help for 52 CONFIG_LOCAL_BOUNDS.) Explicitly check for -fsanitize=array-bounds 53 so that we can build up the options needed for UBSAN_BOUNDS 54 with or without UBSAN_TRAP. 55 56config UBSAN_BOUNDS 57 bool "Perform array index bounds checking" 58 default UBSAN 59 depends on CC_HAS_UBSAN_ARRAY_BOUNDS || CC_HAS_UBSAN_BOUNDS_STRICT 60 help 61 This option enables detection of directly indexed out of bounds 62 array accesses, where the array size is known at compile time. 63 Note that this does not protect array overflows via bad calls 64 to the {str,mem}*cpy() family of functions (that is addressed 65 by CONFIG_FORTIFY_SOURCE). 66 67config UBSAN_BOUNDS_STRICT 68 def_bool UBSAN_BOUNDS && CC_HAS_UBSAN_BOUNDS_STRICT 69 help 70 GCC's bounds sanitizer. This option is used to select the 71 correct options in Makefile.ubsan. 72 73config UBSAN_ARRAY_BOUNDS 74 def_bool UBSAN_BOUNDS && CC_HAS_UBSAN_ARRAY_BOUNDS 75 help 76 Clang's array bounds sanitizer. This option is used to select 77 the correct options in Makefile.ubsan. 78 79config UBSAN_LOCAL_BOUNDS 80 def_bool UBSAN_ARRAY_BOUNDS && UBSAN_TRAP 81 help 82 This option enables Clang's -fsanitize=local-bounds which traps 83 when an access through a pointer that is derived from an object 84 of a statically-known size, where an added offset (which may not 85 be known statically) is out-of-bounds. Since this option is 86 trap-only, it depends on CONFIG_UBSAN_TRAP. 87 88config UBSAN_SHIFT 89 bool "Perform checking for bit-shift overflows" 90 default UBSAN 91 depends on $(cc-option,-fsanitize=shift) 92 help 93 This option enables -fsanitize=shift which checks for bit-shift 94 operations that overflow to the left or go switch to negative 95 for signed types. 96 97config UBSAN_DIV_ZERO 98 bool "Perform checking for integer divide-by-zero" 99 depends on $(cc-option,-fsanitize=integer-divide-by-zero) 100 # https://github.com/ClangBuiltLinux/linux/issues/1657 101 # https://github.com/llvm/llvm-project/issues/56289 102 depends on !CC_IS_CLANG 103 help 104 This option enables -fsanitize=integer-divide-by-zero which checks 105 for integer division by zero. This is effectively redundant with the 106 kernel's existing exception handling, though it can provide greater 107 debugging information under CONFIG_UBSAN_REPORT_FULL. 108 109config UBSAN_UNREACHABLE 110 bool "Perform checking for unreachable code" 111 # objtool already handles unreachable checking and gets angry about 112 # seeing UBSan instrumentation located in unreachable places. 113 depends on !(OBJTOOL && (STACK_VALIDATION || UNWINDER_ORC || HAVE_UACCESS_VALIDATION)) 114 depends on $(cc-option,-fsanitize=unreachable) 115 help 116 This option enables -fsanitize=unreachable which checks for control 117 flow reaching an expected-to-be-unreachable position. 118 119config UBSAN_BOOL 120 bool "Perform checking for non-boolean values used as boolean" 121 default UBSAN 122 depends on $(cc-option,-fsanitize=bool) 123 help 124 This option enables -fsanitize=bool which checks for boolean values being 125 loaded that are neither 0 nor 1. 126 127config UBSAN_ENUM 128 bool "Perform checking for out of bounds enum values" 129 default UBSAN 130 depends on $(cc-option,-fsanitize=enum) 131 help 132 This option enables -fsanitize=enum which checks for values being loaded 133 into an enum that are outside the range of given values for the given enum. 134 135config UBSAN_ALIGNMENT 136 bool "Perform checking for misaligned pointer usage" 137 default !HAVE_EFFICIENT_UNALIGNED_ACCESS 138 depends on !UBSAN_TRAP && !COMPILE_TEST 139 depends on $(cc-option,-fsanitize=alignment) 140 help 141 This option enables the check of unaligned memory accesses. 142 Enabling this option on architectures that support unaligned 143 accesses may produce a lot of false positives. 144 145config UBSAN_SANITIZE_ALL 146 bool "Enable instrumentation for the entire kernel" 147 depends on ARCH_HAS_UBSAN_SANITIZE_ALL 148 default y 149 help 150 This option activates instrumentation for the entire kernel. 151 If you don't enable this option, you have to explicitly specify 152 UBSAN_SANITIZE := y for the files/directories you want to check for UB. 153 Enabling this option will get kernel image size increased 154 significantly. 155 156config TEST_UBSAN 157 tristate "Module for testing for undefined behavior detection" 158 depends on m 159 help 160 This is a test module for UBSAN. 161 It triggers various undefined behavior, and detect it. 162 163endif # if UBSAN 164