# SPDX-License-Identifier: GPL-2.0-only config ARCH_HAS_UBSAN_SANITIZE_ALL bool menuconfig UBSAN bool "Undefined behaviour sanity checker" help This option enables the Undefined Behaviour sanity checker. Compile-time instrumentation is used to detect various undefined behaviours at runtime. For more details, see: Documentation/dev-tools/ubsan.rst if UBSAN config UBSAN_TRAP bool "On Sanitizer warnings, abort the running kernel code" depends on !COMPILE_TEST depends on $(cc-option, -fsanitize-undefined-trap-on-error) help Building kernels with Sanitizer features enabled tends to grow the kernel size by around 5%, due to adding all the debugging text on failure paths. To avoid this, Sanitizer instrumentation can just issue a trap. This reduces the kernel size overhead but turns all warnings (including potentially harmless conditions) into full exceptions that abort the running kernel code (regardless of context, locks held, etc), which may destabilize the system. For some system builders this is an acceptable trade-off. config UBSAN_KCOV_BROKEN def_bool KCOV && CC_HAS_SANCOV_TRACE_PC depends on CC_IS_CLANG depends on !$(cc-option,-Werror=unused-command-line-argument -fsanitize=bounds -fsanitize-coverage=trace-pc) help Some versions of clang support either UBSAN or KCOV but not the combination of the two. See https://bugs.llvm.org/show_bug.cgi?id=45831 for the status in newer releases. config CC_HAS_UBSAN_BOUNDS def_bool $(cc-option,-fsanitize=bounds) config CC_HAS_UBSAN_ARRAY_BOUNDS def_bool $(cc-option,-fsanitize=array-bounds) config UBSAN_BOUNDS bool "Perform array index bounds checking" default UBSAN depends on !UBSAN_KCOV_BROKEN depends on CC_HAS_UBSAN_ARRAY_BOUNDS || CC_HAS_UBSAN_BOUNDS help This option enables detection of directly indexed out of bounds array accesses, where the array size is known at compile time. Note that this does not protect array overflows via bad calls to the {str,mem}*cpy() family of functions (that is addressed by CONFIG_FORTIFY_SOURCE). config UBSAN_ONLY_BOUNDS def_bool CC_HAS_UBSAN_BOUNDS && !CC_HAS_UBSAN_ARRAY_BOUNDS depends on UBSAN_BOUNDS help This is a weird case: Clang's -fsanitize=bounds includes -fsanitize=local-bounds, but it's trapping-only, so for Clang, we must use -fsanitize=array-bounds when we want traditional array bounds checking enabled. For GCC, we want -fsanitize=bounds. config UBSAN_ARRAY_BOUNDS def_bool CC_HAS_UBSAN_ARRAY_BOUNDS depends on UBSAN_BOUNDS config UBSAN_LOCAL_BOUNDS bool "Perform array local bounds checking" depends on UBSAN_TRAP depends on !UBSAN_KCOV_BROKEN depends on $(cc-option,-fsanitize=local-bounds) help This option enables -fsanitize=local-bounds which traps when an exception/error is detected. Therefore, it may only be enabled with CONFIG_UBSAN_TRAP. Enabling this option detects errors due to accesses through a pointer that is derived from an object of a statically-known size, where an added offset (which may not be known statically) is out-of-bounds. config UBSAN_SHIFT bool "Perform checking for bit-shift overflows" default UBSAN depends on $(cc-option,-fsanitize=shift) help This option enables -fsanitize=shift which checks for bit-shift operations that overflow to the left or go switch to negative for signed types. config UBSAN_DIV_ZERO bool "Perform checking for integer divide-by-zero" depends on $(cc-option,-fsanitize=integer-divide-by-zero) help This option enables -fsanitize=integer-divide-by-zero which checks for integer division by zero. This is effectively redundant with the kernel's existing exception handling, though it can provide greater debugging information under CONFIG_UBSAN_REPORT_FULL. config UBSAN_UNREACHABLE bool "Perform checking for unreachable code" # objtool already handles unreachable checking and gets angry about # seeing UBSan instrumentation located in unreachable places. depends on !STACK_VALIDATION depends on $(cc-option,-fsanitize=unreachable) help This option enables -fsanitize=unreachable which checks for control flow reaching an expected-to-be-unreachable position. config UBSAN_OBJECT_SIZE bool "Perform checking for accesses beyond the end of objects" default UBSAN # gcc hugely expands stack usage with -fsanitize=object-size # https://lore.kernel.org/lkml/CAHk-=wjPasyJrDuwDnpHJS2TuQfExwe=px-SzLeN8GFMAQJPmQ@mail.gmail.com/ depends on !CC_IS_GCC depends on $(cc-option,-fsanitize=object-size) help This option enables -fsanitize=object-size which checks for accesses beyond the end of objects where the optimizer can determine both the object being operated on and its size, usually seen with bad downcasts, or access to struct members from NULL pointers. config UBSAN_BOOL bool "Perform checking for non-boolean values used as boolean" default UBSAN depends on $(cc-option,-fsanitize=bool) help This option enables -fsanitize=bool which checks for boolean values being loaded that are neither 0 nor 1. config UBSAN_ENUM bool "Perform checking for out of bounds enum values" default UBSAN depends on $(cc-option,-fsanitize=enum) help This option enables -fsanitize=enum which checks for values being loaded into an enum that are outside the range of given values for the given enum. config UBSAN_ALIGNMENT bool "Perform checking for misaligned pointer usage" default !HAVE_EFFICIENT_UNALIGNED_ACCESS depends on !UBSAN_TRAP && !COMPILE_TEST depends on $(cc-option,-fsanitize=alignment) help This option enables the check of unaligned memory accesses. Enabling this option on architectures that support unaligned accesses may produce a lot of false positives. config UBSAN_SANITIZE_ALL bool "Enable instrumentation for the entire kernel" depends on ARCH_HAS_UBSAN_SANITIZE_ALL default y help This option activates instrumentation for the entire kernel. If you don't enable this option, you have to explicitly specify UBSAN_SANITIZE := y for the files/directories you want to check for UB. Enabling this option will get kernel image size increased significantly. config TEST_UBSAN tristate "Module for testing for undefined behavior detection" depends on m help This is a test module for UBSAN. It triggers various undefined behavior, and detect it. endif # if UBSAN