[PATCH] kasan: fix GCC mem-intrinsic prefix with sw tags

[Ada Couprie Diaz]

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 36be5cba99f6 ("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.

[0]: https://gcc.gnu.org/onlinedocs/gcc-13.4.0/gcc/Optimize-Options.html

Signed-off-by: Ada Couprie Diaz <ada.cou...@arm.com>
Fixes: 36be5cba99f6 ("kasan: treat meminstrinsic as builtins in uninstrumented files")
---
scripts/Makefile.kasan | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan
index 693dbbebebba..0ba2aac3b8dc 100644
--- a/scripts/Makefile.kasan
+++ b/scripts/Makefile.kasan
@@ -86,10 +86,14 @@ kasan_params += hwasan-instrument-stack=$(stack_enable) \
hwasan-use-short-granules=0 \
hwasan-inline-all-checks=0

-# Instrument memcpy/memset/memmove calls by using instrumented __hwasan_mem*().
-ifeq ($(call clang-min-version, 150000)$(call gcc-min-version, 130000),y)
- kasan_params += hwasan-kernel-mem-intrinsic-prefix=1
-endif
+# Instrument memcpy/memset/memmove calls by using instrumented __(hw)asan_mem*().
+ifdef CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX
+ ifdef CONFIG_CC_IS_GCC
+ kasan_params += asan-kernel-mem-intrinsic-prefix=1
+ else
+ kasan_params += hwasan-kernel-mem-intrinsic-prefix=1
+ endif
+endif # CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX

endif # CONFIG_KASAN_SW_TAGS


base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585
--
2.43.0

[Yeoreum Yun]

Reviewed-by: Yeoreum Yun <yeore...@arm.com>

--
Sincerely,
Yeoreum Yun