Files
linux/scripts/Makefile.kasan
Ada Couprie Diaz 392260eb8e kasan: fix GCC mem-intrinsic prefix with sw tags
[ Upstream commit 51337a9a3a ]

GCC doesn't support "hwasan-kernel-mem-intrinsic-prefix", only
"asan-kernel-mem-intrinsic-prefix"[0], while LLVM supports both.  This is
already taken into account when checking
"CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX", but not in the KASAN Makefile
adding those parameters when "CONFIG_KASAN_SW_TAGS" is enabled.

Replace the version check with "CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX",
which already validates that mem-intrinsic prefix parameter can be used,
and choose the correct name depending on compiler.

GCC 13 and above trigger "CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX" which
prevents `mem{cpy,move,set}()` being redefined in "mm/kasan/shadow.c"
since commit 36be5cba99 ("kasan: treat meminstrinsic as builtins in
uninstrumented files"), as we expect the compiler to prefix those calls
with `__(hw)asan_` instead.  But as the option passed to GCC has been
incorrect, the compiler has not been emitting those prefixes, effectively
never calling the instrumented versions of `mem{cpy,move,set}()` with
"CONFIG_KASAN_SW_TAGS" enabled.

If "CONFIG_FORTIFY_SOURCES" is enabled, this issue would be mitigated as
it redefines `mem{cpy,move,set}()` and properly aliases the
`__underlying_mem*()` that will be called to the instrumented versions.

Link: https://lkml.kernel.org/r/20250821120735.156244-1-ada.coupriediaz@arm.com
Link: https://gcc.gnu.org/onlinedocs/gcc-13.4.0/gcc/Optimize-Options.html [0]
Signed-off-by: Ada Couprie Diaz <ada.coupriediaz@arm.com>
Fixes: 36be5cba99 ("kasan: treat meminstrinsic as builtins in uninstrumented files")
Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
[ kasan_params => CFLAGS_KASAN ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-09-19 16:32:01 +02:00

83 lines
2.6 KiB
Makefile

# SPDX-License-Identifier: GPL-2.0
ifdef CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX
# Safe for compiler to generate meminstrinsic calls in uninstrumented files.
CFLAGS_KASAN_NOSANITIZE :=
else
# Don't let compiler generate memintrinsic calls in uninstrumented files
# because they are instrumented.
CFLAGS_KASAN_NOSANITIZE := -fno-builtin
endif
KASAN_SHADOW_OFFSET ?= $(CONFIG_KASAN_SHADOW_OFFSET)
cc-param = $(call cc-option, -mllvm -$(1), $(call cc-option, --param $(1)))
ifdef CONFIG_KASAN_STACK
stack_enable := 1
else
stack_enable := 0
endif
ifdef CONFIG_KASAN_GENERIC
ifdef CONFIG_KASAN_INLINE
call_threshold := 10000
else
call_threshold := 0
endif
CFLAGS_KASAN_MINIMAL := -fsanitize=kernel-address
# -fasan-shadow-offset fails without -fsanitize
CFLAGS_KASAN_SHADOW := $(call cc-option, -fsanitize=kernel-address \
-fasan-shadow-offset=$(KASAN_SHADOW_OFFSET), \
$(call cc-option, -fsanitize=kernel-address \
-mllvm -asan-mapping-offset=$(KASAN_SHADOW_OFFSET)))
ifeq ($(strip $(CFLAGS_KASAN_SHADOW)),)
CFLAGS_KASAN := $(CFLAGS_KASAN_MINIMAL)
else
# Now add all the compiler specific options that are valid standalone
CFLAGS_KASAN := $(CFLAGS_KASAN_SHADOW) \
$(call cc-param,asan-globals=1) \
$(call cc-param,asan-instrumentation-with-call-threshold=$(call_threshold)) \
$(call cc-param,asan-instrument-allocas=1)
endif
CFLAGS_KASAN += $(call cc-param,asan-stack=$(stack_enable))
# Instrument memcpy/memset/memmove calls by using instrumented __asan_mem*()
# instead. With compilers that don't support this option, compiler-inserted
# memintrinsics won't be checked by KASAN on GENERIC_ENTRY architectures.
CFLAGS_KASAN += $(call cc-param,asan-kernel-mem-intrinsic-prefix=1)
endif # CONFIG_KASAN_GENERIC
ifdef CONFIG_KASAN_SW_TAGS
ifdef CONFIG_KASAN_INLINE
instrumentation_flags := $(call cc-param,hwasan-mapping-offset=$(KASAN_SHADOW_OFFSET))
else
instrumentation_flags := $(call cc-param,hwasan-instrument-with-calls=1)
endif
CFLAGS_KASAN := -fsanitize=kernel-hwaddress \
$(call cc-param,hwasan-instrument-stack=$(stack_enable)) \
$(call cc-param,hwasan-use-short-granules=0) \
$(call cc-param,hwasan-inline-all-checks=0) \
$(instrumentation_flags)
# Instrument memcpy/memset/memmove calls by using instrumented __(hw)asan_mem*().
ifdef CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX
ifdef CONFIG_CC_IS_GCC
CFLAGS_KASAN += $(call cc-param,asan-kernel-mem-intrinsic-prefix=1)
else
CFLAGS_KASAN += $(call cc-param,hwasan-kernel-mem-intrinsic-prefix=1)
endif
endif # CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX
endif # CONFIG_KASAN_SW_TAGS
export CFLAGS_KASAN CFLAGS_KASAN_NOSANITIZE