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Subject[PATCH 1/4] ubsan: Move cc-option tests into Kconfig
Date
Instead of doing if/endif blocks with cc-option calls in the UBSAN
Makefile, move all the tests into Kconfig and use the Makefile to
collect the results.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/lkml/CAHk-=wjPasyJrDuwDnpHJS2TuQfExwe=px-SzLeN8GFMAQJPmQ@mail.gmail.com/
Signed-off-by: Kees Cook <keescook@chromium.org>
---
lib/Kconfig.ubsan | 48 +++++++++++++++++++++++++++++++++++++++-
scripts/Makefile.ubsan | 50 ++++++++++++++----------------------------
2 files changed, 64 insertions(+), 34 deletions(-)

diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan
index 58f8d03d037b..c0b801871e0b 100644
--- a/lib/Kconfig.ubsan
+++ b/lib/Kconfig.ubsan
@@ -36,10 +36,17 @@ config UBSAN_KCOV_BROKEN
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.
@@ -47,11 +54,17 @@ config UBSAN_BOUNDS
to the {str,mem}*cpy() family of functions (that is addressed
by CONFIG_FORTIFY_SOURCE).

+config CC_ARG_UBSAN_BOUNDS
+ string
+ default "-fsanitize=array-bounds" if CC_HAS_UBSAN_ARRAY_BOUNDS
+ default "-fsanitize=bounds"
+ depends on UBSAN_BOUNDS
+
config UBSAN_LOCAL_BOUNDS
bool "Perform array local bounds checking"
depends on UBSAN_TRAP
- depends on CC_IS_CLANG
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 should be enabled only
@@ -69,6 +82,38 @@ config UBSAN_MISC
own Kconfig options. Disable this if you only want to have
individually selected checks.

+config UBSAN_SHIFT
+ def_bool UBSAN_MISC
+ depends on $(cc-option,-fsanitize=shift)
+
+config UBSAN_DIV_ZERO
+ def_bool UBSAN_MISC
+ depends on $(cc-option,-fsanitize=integer-divide-by-zero)
+
+config UBSAN_UNREACHABLE
+ def_bool UBSAN_MISC
+ depends on $(cc-option,-fsanitize=unreachable)
+
+config UBSAN_SIGNED_OVERFLOW
+ def_bool UBSAN_MISC
+ depends on $(cc-option,-fsanitize=signed-integer-overflow)
+
+config UBSAN_UNSIGNED_OVERFLOW
+ def_bool UBSAN_MISC
+ depends on $(cc-option,-fsanitize=unsigned-integer-overflow)
+
+config UBSAN_OBJECT_SIZE
+ def_bool UBSAN_MISC
+ depends on $(cc-option,-fsanitize=object-size)
+
+config UBSAN_BOOL
+ def_bool UBSAN_MISC
+ depends on $(cc-option,-fsanitize=bool)
+
+config UBSAN_ENUM
+ def_bool UBSAN_MISC
+ depends on $(cc-option,-fsanitize=enum)
+
config UBSAN_SANITIZE_ALL
bool "Enable instrumentation for the entire kernel"
depends on ARCH_HAS_UBSAN_SANITIZE_ALL
@@ -89,6 +134,7 @@ config UBSAN_ALIGNMENT
bool "Enable checks for pointers alignment"
default !HAVE_EFFICIENT_UNALIGNED_ACCESS
depends on !UBSAN_TRAP
+ depends on $(cc-option,-fsanitize=alignment)
help
This option enables the check of unaligned memory accesses.
Enabling this option on architectures that support unaligned
diff --git a/scripts/Makefile.ubsan b/scripts/Makefile.ubsan
index 9716dab06bc7..72862da47baf 100644
--- a/scripts/Makefile.ubsan
+++ b/scripts/Makefile.ubsan
@@ -1,37 +1,21 @@
# SPDX-License-Identifier: GPL-2.0

-export CFLAGS_UBSAN :=
+# -fsanitize=* options makes GCC less smart than usual and
+# increases the number of 'maybe-uninitialized' false-positives.
+ubsan-cflags-$(CONFIG_UBSAN) += $(call cc-disable-warning, maybe-uninitialized)

-ifdef CONFIG_UBSAN_ALIGNMENT
- CFLAGS_UBSAN += $(call cc-option, -fsanitize=alignment)
-endif
+# Enable available and selected UBSAN features.
+ubsan-cflags-$(CONFIG_UBSAN_ALIGNMENT) += -fsanitize=alignment
+ubsan-cflags-$(CONFIG_UBSAN_BOUNDS) += $(CONFIG_CC_ARG_UBSAN_BOUNDS)
+ubsan-cflags-$(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_OVERFLOW) += -fsanitize=signed-integer-overflow
+ubsan-cflags-$(CONFIG_UBSAN_UNSIGNED_OVERFLOW) += -fsanitize=unsigned-integer-overflow
+ubsan-cflags-$(CONFIG_UBSAN_OBJECT_SIZE) += -fsanitize=object-size
+ubsan-cflags-$(CONFIG_UBSAN_BOOL) += -fsanitize=bool
+ubsan-cflags-$(CONFIG_UBSAN_ENUM) += -fsanitize=enum
+ubsan-cflags-$(CONFIG_UBSAN_TRAP) += -fsanitize-undefined-trap-on-error

-ifdef CONFIG_UBSAN_BOUNDS
- ifdef CONFIG_CC_IS_CLANG
- CFLAGS_UBSAN += -fsanitize=array-bounds
- else
- CFLAGS_UBSAN += $(call cc-option, -fsanitize=bounds)
- endif
-endif
-
-ifdef CONFIG_UBSAN_LOCAL_BOUNDS
- CFLAGS_UBSAN += -fsanitize=local-bounds
-endif
-
-ifdef CONFIG_UBSAN_MISC
- CFLAGS_UBSAN += $(call cc-option, -fsanitize=shift)
- CFLAGS_UBSAN += $(call cc-option, -fsanitize=integer-divide-by-zero)
- CFLAGS_UBSAN += $(call cc-option, -fsanitize=unreachable)
- CFLAGS_UBSAN += $(call cc-option, -fsanitize=signed-integer-overflow)
- CFLAGS_UBSAN += $(call cc-option, -fsanitize=object-size)
- CFLAGS_UBSAN += $(call cc-option, -fsanitize=bool)
- CFLAGS_UBSAN += $(call cc-option, -fsanitize=enum)
-endif
-
-ifdef CONFIG_UBSAN_TRAP
- CFLAGS_UBSAN += $(call cc-option, -fsanitize-undefined-trap-on-error)
-endif
-
- # -fsanitize=* options makes GCC less smart than usual and
- # increase number of 'maybe-uninitialized false-positives
- CFLAGS_UBSAN += $(call cc-option, -Wno-maybe-uninitialized)
+export CFLAGS_UBSAN := $(ubsan-cflags-y)
--
2.25.1
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