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Subject[PATCH 5.0 041/246] kasan: fix kasan_check_read/write definitions
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5.0-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit bcf6f55a0d05eedd8ebb6ecc60ae3f93205ad833 ]

Building little-endian allmodconfig kernels on arm64 started failing
with the generated atomic.h implementation, since we now try to call
kasan helpers from the EFI stub:

aarch64-linux-gnu-ld: drivers/firmware/efi/libstub/arm-stub.stub.o: in function `atomic_set':
include/generated/atomic-instrumented.h:44: undefined reference to `__efistub_kasan_check_write'

I suspect that we get similar problems in other files that explicitly
disable KASAN for some reason but call atomic_t based helper functions.

We can fix this by checking the predefined __SANITIZE_ADDRESS__ macro
that the compiler sets instead of checking CONFIG_KASAN, but this in
turn requires a small hack in mm/kasan/common.c so we do see the extern
declaration there instead of the inline function.

Link: http://lkml.kernel.org/r/20181211133453.2835077-1-arnd@arndb.de
Fixes: b1864b828644 ("locking/atomics: build atomic headers as required")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: Anders Roxell <anders.roxell@linaro.org>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>,
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/kasan-checks.h | 2 +-
mm/kasan/common.c | 2 ++
2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/linux/kasan-checks.h b/include/linux/kasan-checks.h
index d314150658a4..a61dc075e2ce 100644
--- a/include/linux/kasan-checks.h
+++ b/include/linux/kasan-checks.h
@@ -2,7 +2,7 @@
#ifndef _LINUX_KASAN_CHECKS_H
#define _LINUX_KASAN_CHECKS_H

-#ifdef CONFIG_KASAN
+#if defined(__SANITIZE_ADDRESS__) || defined(__KASAN_INTERNAL)
void kasan_check_read(const volatile void *p, unsigned int size);
void kasan_check_write(const volatile void *p, unsigned int size);
#else
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 09b534fbba17..80bbe62b16cd 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -14,6 +14,8 @@
*
*/

+#define __KASAN_INTERNAL
+
#include <linux/export.h>
#include <linux/interrupt.h>
#include <linux/init.h>
--
2.19.1


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