Messages in this thread Patch in this message | | | From | Nick Desaulniers <> | Subject | [PATCH v2] arm64: avoid overflow in VA_START and PAGE_OFFSET | Date | Thu, 3 Aug 2017 11:03:58 -0700 |
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The bitmask used to define these values produces overflow, as seen by this compiler warning:
arch/arm64/kernel/head.S:47:8: warning: integer overflow in preprocessor expression #elif (PAGE_OFFSET & 0x1fffff) != 0 ^~~~~~~~~~~ arch/arm64/include/asm/memory.h:52:46: note: expanded from macro 'PAGE_OFFSET' #define PAGE_OFFSET (UL(0xffffffffffffffff) << (VA_BITS - 1)) ~~~~~~~~~~~~~~~~~~ ^
It would be preferrable to use GENMASK_ULL() instead, but it's not set up to be used from assembly (the UL() macro token pastes UL suffixes when not included in assembly sources).
Suggested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Suggested-by: Yury Norov <ynorov@caviumnetworks.com> Suggested-by: Matthias Kaehlcke <mka@chromium.org> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> --- arch/arm64/include/asm/memory.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h index 32f82723338a..ef39dcb9ca6a 100644 --- a/arch/arm64/include/asm/memory.h +++ b/arch/arm64/include/asm/memory.h @@ -64,8 +64,10 @@ * TASK_UNMAPPED_BASE - the lower boundary of the mmap VM area. */ #define VA_BITS (CONFIG_ARM64_VA_BITS) -#define VA_START (UL(0xffffffffffffffff) << VA_BITS) -#define PAGE_OFFSET (UL(0xffffffffffffffff) << (VA_BITS - 1)) +#define VA_START (UL(0xffffffffffffffff) - \ + (UL(1) << VA_BITS) + 1) +#define PAGE_OFFSET (UL(0xffffffffffffffff) - \ + (UL(1) << (VA_BITS - 1)) + 1) #define KIMAGE_VADDR (MODULES_END) #define MODULES_END (MODULES_VADDR + MODULES_VSIZE) #define MODULES_VADDR (VA_START + KASAN_SHADOW_SIZE) -- 2.14.0.rc1.383.gd1ce394fe2-goog
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