Ada Couprie Diaz 28ef61701e kasan: fix GCC mem-intrinsic prefix with sw tags ...

commit 51337a9a3a upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2025-09-09 18:58:16 +02:00

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