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kasan: treat meminstrinsic as builtins in uninstrumented files

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Where the compiler instruments meminstrinsics by generating calls to
__asan/__hwasan_ prefixed functions, let the compiler consider
memintrinsics as builtin again.

To do so, never override memset/memmove/memcpy if the compiler does the
correct instrumentation - even on !GENERIC_ENTRY architectures.

[elver@google.com: powerpc: don't rename memintrinsics if compiler adds prefixes]
  Link: https://lore.kernel.org/all/20230224085942.1791837-1-elver@google.com/ [1]
  Link: https://lkml.kernel.org/r/20230227094726.3833247-1-elver@google.com
Link: https://lkml.kernel.org/r/20230224085942.1791837-2-elver@google.com
Fixes: 69d4c0d321 ("entry, kasan, x86: Disallow overriding mem*() functions")
Signed-off-by: Marco Elver <elver@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jakub Jelinek <jakub@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Nicolas Schier <nicolas@fjasle.eu>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Marco Elver 2023-02-24 09:59:40 +01:00 • committed by Andrew Morton
parent 51287dcb00
commit 36be5cba99
3 changed files with 22 additions and 1 deletions
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9
lib/Kconfig.kasan
View file

@ -49,6 +49,15 @@ menuconfig KASAN
if KASAN if KASAN
config CC_HAS_KASAN_MEMINTRINSIC_PREFIX
def_bool (CC_IS_CLANG && $(cc-option,-fsanitize=kernel-address -mllvm -asan-kernel-mem-intrinsic-prefix=1)) || \
(CC_IS_GCC && $(cc-option,-fsanitize=kernel-address --param asan-kernel-mem-intrinsic-prefix=1))
# Don't define it if we don't need it: compilation of the test uses
# this variable to decide how the compiler should treat builtins.
depends on !KASAN_HW_TAGS
help
The compiler is able to prefix memintrinsics with __asan or __hwasan.
choice choice
prompt "KASAN mode" prompt "KASAN mode"
default KASAN_GENERIC default KASAN_GENERIC

5
mm/kasan/shadow.c
View file

@ -38,11 +38,14 @@ bool __kasan_check_write(const volatile void *p, unsigned int size)
} }
EXPORT_SYMBOL(__kasan_check_write); EXPORT_SYMBOL(__kasan_check_write);
#ifndef CONFIG_GENERIC_ENTRY #if !defined(CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX) && !defined(CONFIG_GENERIC_ENTRY)
/* /*
* CONFIG_GENERIC_ENTRY relies on compiler emitted mem*() calls to not be * CONFIG_GENERIC_ENTRY relies on compiler emitted mem*() calls to not be
* instrumented. KASAN enabled toolchains should emit __asan_mem*() functions * instrumented. KASAN enabled toolchains should emit __asan_mem*() functions
* for the sites they want to instrument. * for the sites they want to instrument.
*
* If we have a compiler that can instrument meminstrinsics, never override
* these, so that non-instrumented files can safely consider them as builtins.
*/ */
#undef memset #undef memset
void *memset(void *addr, int c, size_t len) void *memset(void *addr, int c, size_t len)

9
scripts/Makefile.kasan
View file

@ -1,5 +1,14 @@
# SPDX-License-Identifier: GPL-2.0 # 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 CFLAGS_KASAN_NOSANITIZE := -fno-builtin
endif
KASAN_SHADOW_OFFSET ?= $(CONFIG_KASAN_SHADOW_OFFSET) KASAN_SHADOW_OFFSET ?= $(CONFIG_KASAN_SHADOW_OFFSET)
cc-param = $(call cc-option, -mllvm -$(1), $(call cc-option, --param $(1))) cc-param = $(call cc-option, -mllvm -$(1), $(call cc-option, --param $(1)))