The patch titled
Subject: kasan: use IS_ALIGNED in memory_is_poisoned_8()
has been added to the -mm tree. Its filename is
kasan-use-is_aligned-in-memory_is_poisoned_8.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kasan-use-is_aligned-in-memory_is_poisoned_8.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kasan-use-is_aligned-in-memory_is_poisoned_8.patch
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------------------------------------------------------
From: Xishi Qiu <qiuxishi@xxxxxxxxxx>
Subject: kasan: use IS_ALIGNED in memory_is_poisoned_8()
Use IS_ALIGNED() to determine whether the shadow span two bytes. It
generates less code and more readable. Add some comments in shadow check
functions.
Please apply "kasan: fix last shadow judgement in memory_is_poisoned_16()"
first.
Signed-off-by: Xishi Qiu <qiuxishi@xxxxxxxxxx>
Cc: Andrey Konovalov <adech.fo@xxxxxxxxx>
Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/kasan/kasan.c | 21 +++++++++++++++++++--
1 file changed, 19 insertions(+), 2 deletions(-)
diff -puN mm/kasan/kasan.c~kasan-use-is_aligned-in-memory_is_poisoned_8 mm/kasan/kasan.c
--- a/mm/kasan/kasan.c~kasan-use-is_aligned-in-memory_is_poisoned_8
+++ a/mm/kasan/kasan.c
@@ -86,6 +86,10 @@ static __always_inline bool memory_is_po
if (memory_is_poisoned_1(addr + 1))
return true;
+ /*
+ * If the shadow spans two bytes, the first byte should
+ * be zero.
+ */
if (likely(((addr + 1) & KASAN_SHADOW_MASK) != 0))
return false;
@@ -103,6 +107,10 @@ static __always_inline bool memory_is_po
if (memory_is_poisoned_1(addr + 3))
return true;
+ /*
+ * If the shadow spans two bytes, the first byte should
+ * be zero.
+ */
if (likely(((addr + 3) & KASAN_SHADOW_MASK) >= 3))
return false;
@@ -120,7 +128,11 @@ static __always_inline bool memory_is_po
if (memory_is_poisoned_1(addr + 7))
return true;
- if (likely(((addr + 7) & KASAN_SHADOW_MASK) >= 7))
+ /*
+ * If the shadow spans two bytes, the first byte should
+ * be zero.
+ */
+ if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
return false;
return unlikely(*(u8 *)shadow_addr);
@@ -139,7 +151,12 @@ static __always_inline bool memory_is_po
if (unlikely(shadow_first_bytes))
return true;
- if (likely(IS_ALIGNED(addr, 8)))
+ /*
+ * If the shadow spans three bytes, we should continue to
+ * check the last byte. The first two bytes which we
+ * checked above should always be zero.
+ */
+ if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
return false;
return memory_is_poisoned_1(addr + 15);
_
Patches currently in -mm which might be from qiuxishi@xxxxxxxxxx are
kasan-fix-last-shadow-judgement-in-memory_is_poisoned_16.patch
kasan-use-is_aligned-in-memory_is_poisoned_8.patch
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