[PATCH 4.9 032/102] arm64: avoid overflow in VA_START and PAGE_OFFSET

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

--

From: Nick Desaulniers 

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 & 0x1f) != 0
 ^~~
arch/arm64/include/asm/memory.h:52:46: note:
  expanded from macro 'PAGE_OFFSET'
  #define PAGE_OFFSET (UL(0x) << (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 
Suggested-by: Yury Norov 
Suggested-by: Matthias Kaehlcke 
Signed-off-by: Nick Desaulniers 
Signed-off-by: Will Deacon 
Cc: Nathan Chancellor 
Signed-off-by: Greg Kroah-Hartman 

---
 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(0x) << VA_BITS)
-#define PAGE_OFFSET(UL(0x) << (VA_BITS - 1))
+#define VA_START   (UL(0x) - \
+   (UL(1) << VA_BITS) + 1)
+#define PAGE_OFFSET(UL(0x) - \
+   (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)

[PATCH 4.9 032/102] arm64: avoid overflow in VA_START and PAGE_OFFSET

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

--

From: Nick Desaulniers 

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 & 0x1f) != 0
 ^~~
arch/arm64/include/asm/memory.h:52:46: note:
  expanded from macro 'PAGE_OFFSET'
  #define PAGE_OFFSET (UL(0x) << (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 
Suggested-by: Yury Norov 
Suggested-by: Matthias Kaehlcke 
Signed-off-by: Nick Desaulniers 
Signed-off-by: Will Deacon 
Cc: Nathan Chancellor 
Signed-off-by: Greg Kroah-Hartman 

---
 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(0x) << VA_BITS)
-#define PAGE_OFFSET(UL(0x) << (VA_BITS - 1))
+#define VA_START   (UL(0x) - \
+   (UL(1) << VA_BITS) + 1)
+#define PAGE_OFFSET(UL(0x) - \
+   (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)