[PATCH 5/6] ubsan: Split wrapping sanitizer Makefile rules

[Kees Cook]

To allow for fine-grained control of where the wrapping sanitizers can
be disabled, split them from the main UBSAN CFLAGS into their own set of
rules.

Cc: Masahiro Yamada <masahiroy@xxxxxxxxxx>
Cc: Nathan Chancellor <nathan@xxxxxxxxxx>
Cc: Nicolas Schier <nicolas@xxxxxxxxx>
Cc: linux-kbuild@xxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
 scripts/Makefile.lib   |  9 +++++++++
 scripts/Makefile.ubsan | 12 +++++++++---
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 52efc520ae4f..5ce4f4e0bc61 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -177,6 +177,15 @@ ifeq ($(CONFIG_UBSAN),y)
 _c_flags += $(if $(patsubst n%,, \
 		$(UBSAN_SANITIZE_$(basetarget).o)$(UBSAN_SANITIZE)y), \
 		$(CFLAGS_UBSAN))
+_c_flags += $(if $(patsubst n%,, \
+		$(UBSAN_WRAP_SIGNED_$(basetarget).o)$(UBSAN_SANITIZE_$(basetarget).o)$(UBSAN_WRAP_SIGNED)$(UBSAN_SANITIZE)y), \
+		$(CFLAGS_UBSAN_WRAP_SIGNED))
+_c_flags += $(if $(patsubst n%,, \
+		$(UBSAN_WRAP_UNSIGNED_$(basetarget).o)$(UBSAN_SANITIZE_$(basetarget).o)$(UBSAN_WRAP_UNSIGNED)$(UBSAN_SANITIZE)y), \
+		$(CFLAGS_UBSAN_WRAP_UNSIGNED))
+_c_flags += $(if $(patsubst n%,, \
+		$(UBSAN_WRAP_POINTER_$(basetarget).o)$(UBSAN_SANITIZE_$(basetarget).o)$(UBSAN_WRAP_POINTER)$(UBSAN_SANITIZE)y), \
+		$(CFLAGS_UBSAN_WRAP_POINTER))
 endif
 
 ifeq ($(CONFIG_KCOV),y)
diff --git a/scripts/Makefile.ubsan b/scripts/Makefile.ubsan
index df4ccf063f67..6b1e65583d6f 100644
--- a/scripts/Makefile.ubsan
+++ b/scripts/Makefile.ubsan
@@ -8,11 +8,17 @@ ubsan-cflags-$(CONFIG_UBSAN_LOCAL_BOUNDS)	+= -fsanitize=local-bounds
 ubsan-cflags-$(CONFIG_UBSAN_SHIFT)		+= -fsanitize=shift
 ubsan-cflags-$(CONFIG_UBSAN_DIV_ZERO)		+= -fsanitize=integer-divide-by-zero
 ubsan-cflags-$(CONFIG_UBSAN_UNREACHABLE)	+= -fsanitize=unreachable
-ubsan-cflags-$(CONFIG_UBSAN_SIGNED_WRAP)	+= -fsanitize=signed-integer-overflow
-ubsan-cflags-$(CONFIG_UBSAN_UNSIGNED_WRAP)	+= -fsanitize=unsigned-integer-overflow
-ubsan-cflags-$(CONFIG_UBSAN_POINTER_WRAP)	+= -fsanitize=pointer-overflow
 ubsan-cflags-$(CONFIG_UBSAN_BOOL)		+= -fsanitize=bool
 ubsan-cflags-$(CONFIG_UBSAN_ENUM)		+= -fsanitize=enum
 ubsan-cflags-$(CONFIG_UBSAN_TRAP)		+= $(call cc-option,-fsanitize-trap=undefined,-fsanitize-undefined-trap-on-error)
 
 export CFLAGS_UBSAN := $(ubsan-cflags-y)
+
+ubsan-wrap-signed-cflags-$(CONFIG_UBSAN_SIGNED_WRAP)     += -fsanitize=signed-integer-overflow
+export CFLAGS_UBSAN_WRAP_SIGNED := $(ubsan-wrap-signed-cflags-y)
+
+ubsan-wrap-unsigned-cflags-$(CONFIG_UBSAN_UNSIGNED_WRAP) += -fsanitize=unsigned-integer-overflow
+export CFLAGS_UBSAN_WRAP_UNSIGNED := $(ubsan-wrap-unsigned-cflags-y)
+
+ubsan-wrap-pointer-cflags-$(CONFIG_UBSAN_POINTER_WRAP)   += -fsanitize=pointer-overflow
+export CFLAGS_UBSAN_WRAP_POINTER := $(ubsan-wrap-pointer-cflags-y)
-- 
2.34.1