| Message ID | 20250307041914.937329-2-kees@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | ubsan/overflow: Enable pattern exclusions | expand |
Hi, On Thu, Mar 06, 2025 at 08:19:10PM -0800, Kees Cook wrote: > To make integer wrap-around mitigation actually useful, the associated > sanitizers must not instrument cases where the wrap-around is explicitly > defined (e.g. "-2UL"), being tested for (e.g. "if (a + b < a)"), or > where it has no impact on code flow (e.g. "while (var--)"). Enable > pattern exclusions for the integer wrap sanitizers. > > Signed-off-by: Kees Cook <kees@kernel.org> > --- > Cc: Justin Stitt <justinstitt@google.com> > Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org> > Cc: Masahiro Yamada <masahiroy@kernel.org> > Cc: Nathan Chancellor <nathan@kernel.org> > Cc: Nicolas Schier <nicolas@fjasle.eu> > Cc: Marco Elver <elver@google.com> > Cc: Andrey Konovalov <andreyknvl@gmail.com> > Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> > Cc: linux-kbuild@vger.kernel.org > Cc: kasan-dev@googlegroups.com > Cc: linux-hardening@vger.kernel.org > --- > lib/Kconfig.ubsan | 1 + > scripts/Makefile.ubsan | 1 + > 2 files changed, 2 insertions(+) > > diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan > index 63e5622010e0..888c2e72c586 100644 > --- a/lib/Kconfig.ubsan > +++ b/lib/Kconfig.ubsan > @@ -120,6 +120,7 @@ config UBSAN_INTEGER_WRAP > bool "Perform checking for integer arithmetic wrap-around" > default UBSAN > depends on !COMPILE_TEST > + depends on $(cc-option,-fsanitize-undefined-ignore-overflow-pattern=all) This option group "all" may be expanded in the future, e.g., negations of unsigned integers (not just unsigned integer literals). As these are deliberately designed for the kernel, I think we will want them anyways. So, all is good. > depends on $(cc-option,-fsanitize=signed-integer-overflow) > depends on $(cc-option,-fsanitize=unsigned-integer-overflow) > depends on $(cc-option,-fsanitize=implicit-signed-integer-truncation) > diff --git a/scripts/Makefile.ubsan b/scripts/Makefile.ubsan > index 4fad9afed24c..233379c193a7 100644 > --- a/scripts/Makefile.ubsan > +++ b/scripts/Makefile.ubsan > @@ -15,6 +15,7 @@ ubsan-cflags-$(CONFIG_UBSAN_TRAP) += $(call cc-option,-fsanitize-trap=undefined > export CFLAGS_UBSAN := $(ubsan-cflags-y) > > ubsan-integer-wrap-cflags-$(CONFIG_UBSAN_INTEGER_WRAP) += \ > + -fsanitize-undefined-ignore-overflow-pattern=all \ > -fsanitize=signed-integer-overflow \ > -fsanitize=unsigned-integer-overflow \ > -fsanitize=implicit-signed-integer-truncation \ > -- > 2.34.1 > Reviewed-by: Justin Stitt <justinstitt@google.com> Justin
diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan index 63e5622010e0..888c2e72c586 100644 --- a/lib/Kconfig.ubsan +++ b/lib/Kconfig.ubsan @@ -120,6 +120,7 @@ config UBSAN_INTEGER_WRAP bool "Perform checking for integer arithmetic wrap-around" default UBSAN depends on !COMPILE_TEST + depends on $(cc-option,-fsanitize-undefined-ignore-overflow-pattern=all) depends on $(cc-option,-fsanitize=signed-integer-overflow) depends on $(cc-option,-fsanitize=unsigned-integer-overflow) depends on $(cc-option,-fsanitize=implicit-signed-integer-truncation) diff --git a/scripts/Makefile.ubsan b/scripts/Makefile.ubsan index 4fad9afed24c..233379c193a7 100644 --- a/scripts/Makefile.ubsan +++ b/scripts/Makefile.ubsan @@ -15,6 +15,7 @@ ubsan-cflags-$(CONFIG_UBSAN_TRAP) += $(call cc-option,-fsanitize-trap=undefined export CFLAGS_UBSAN := $(ubsan-cflags-y) ubsan-integer-wrap-cflags-$(CONFIG_UBSAN_INTEGER_WRAP) += \ + -fsanitize-undefined-ignore-overflow-pattern=all \ -fsanitize=signed-integer-overflow \ -fsanitize=unsigned-integer-overflow \ -fsanitize=implicit-signed-integer-truncation \
To make integer wrap-around mitigation actually useful, the associated sanitizers must not instrument cases where the wrap-around is explicitly defined (e.g. "-2UL"), being tested for (e.g. "if (a + b < a)"), or where it has no impact on code flow (e.g. "while (var--)"). Enable pattern exclusions for the integer wrap sanitizers. Signed-off-by: Kees Cook <kees@kernel.org> --- Cc: Justin Stitt <justinstitt@google.com> Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Nicolas Schier <nicolas@fjasle.eu> Cc: Marco Elver <elver@google.com> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: linux-kbuild@vger.kernel.org Cc: kasan-dev@googlegroups.com Cc: linux-hardening@vger.kernel.org --- lib/Kconfig.ubsan | 1 + scripts/Makefile.ubsan | 1 + 2 files changed, 2 insertions(+)