On Fri, Jul 01, 2022 at 04:22PM +0200, 'Alexander Potapenko' via kasan-dev wrote: [...] > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 2e24db4bff192..59819e6fa5865 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -963,6 +963,7 @@ config DEBUG_STACKOVERFLOW > > source "lib/Kconfig.kasan" > source "lib/Kconfig.kfence" > +source "lib/Kconfig.kmsan" > > endmenu # "Memory Debugging" > > diff --git a/lib/Kconfig.kmsan b/lib/Kconfig.kmsan > new file mode 100644 > index 0000000000000..8f768d4034e3c > --- /dev/null > +++ b/lib/Kconfig.kmsan > @@ -0,0 +1,50 @@ > +# SPDX-License-Identifier: GPL-2.0-only > +config HAVE_ARCH_KMSAN > + bool > + > +config HAVE_KMSAN_COMPILER > + # Clang versions <14.0.0 also support -fsanitize=kernel-memory, but not > + # all the features necessary to build the kernel with KMSAN. > + depends on CC_IS_CLANG && CLANG_VERSION >= 140000 > + def_bool $(cc-option,-fsanitize=kernel-memory -mllvm -msan-disable-checks=1) > + > +config HAVE_KMSAN_PARAM_RETVAL > + # Separate check for -fsanitize-memory-param-retval support. This comment doesn't add much value, maybe instead say that "Supported only by Clang >= 15." > + depends on CC_IS_CLANG && CLANG_VERSION >= 140000 Why not just "depends on HAVE_KMSAN_COMPILER"? (All fsanitize-memory-param-retval supporting compilers must also be KMSAN compilers.) > + def_bool $(cc-option,-fsanitize=kernel-memory -fsanitize-memory-param-retval) > + > + HAVE_KMSAN_PARAM_RETVAL should be moved under "if KMSAN" so that this isn't unnecessarily evaluated in every kernel build (saving 1 shelling out to clang in most builds). > +config KMSAN > + bool "KMSAN: detector of uninitialized values use" > + depends on HAVE_ARCH_KMSAN && HAVE_KMSAN_COMPILER > + depends on SLUB && DEBUG_KERNEL && !KASAN && !KCSAN > + select STACKDEPOT > + select STACKDEPOT_ALWAYS_INIT > + help > + KernelMemorySanitizer (KMSAN) is a dynamic detector of uses of > + uninitialized values in the kernel. It is based on compiler > + instrumentation provided by Clang and thus requires Clang to build. > + > + An important note is that KMSAN is not intended for production use, > + because it drastically increases kernel memory footprint and slows > + the whole system down. > + > + See <file:Documentation/dev-tools/kmsan.rst> for more details. > + > +if KMSAN > + > +config KMSAN_CHECK_PARAM_RETVAL > + bool "Check for uninitialized values passed to and returned from functions" > + default HAVE_KMSAN_PARAM_RETVAL This can be enabled even if !HAVE_KMSAN_PARAM_RETVAL. Should this be: default y depends on HAVE_KMSAN_PARAM_RETVAL instead? > + help > + If the compiler supports -fsanitize-memory-param-retval, KMSAN will > + eagerly check every function parameter passed by value and every > + function return value. > + > + Disabling KMSAN_CHECK_PARAM_RETVAL will result in tracking shadow for > + function parameters and return values across function borders. This > + is a more relaxed mode, but it generates more instrumentation code and > + may potentially report errors in corner cases when non-instrumented > + functions call instrumented ones. > +
