| From 82cd588052815eb4146f9f7c5347ca5e32c56360 Mon Sep 17 00:00:00 2001 |
| From: Nick Desaulniers <ndesaulniers@google.com> |
| Date: Thu, 3 Aug 2017 11:03:58 -0700 |
| Subject: arm64: avoid overflow in VA_START and PAGE_OFFSET |
| |
| From: Nick Desaulniers <ndesaulniers@google.com> |
| |
| commit 82cd588052815eb4146f9f7c5347ca5e32c56360 upstream. |
| |
| 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> |
| Signed-off-by: Will Deacon <will.deacon@arm.com> |
| Cc: Nathan Chancellor <natechancellor@gmail.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/arm64/include/asm/memory.h | 6 ++++-- |
| 1 file changed, 4 insertions(+), 2 deletions(-) |
| |
| --- 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) |