[PATCH v6 0/2] kasan: solve redzone overwritten issue at debug

[<yee.lee@mediatek.com>]

From: Yee Lee <yee.lee@mediatek.com>

Issue: In SLUB debug, hwtag kasan_unpoison() would overwrite the redzone
in those objects with unaligned size.

The first patch Introduces slub_debug_enable_unlikely() to check
the state of debug mode.

The second patch Adds memzero_explict() to separate the initialization for
such condition. The new code path is executed about 1.1% during nromal
booting process. The penalty is acceptable since it only works in debug
mode.

=============
Exp: QEMUv5.2(+mte)/SLUB_debug mode
code path exec : 941/80854 (1.1%)

Changed since v6:
 - Move helper instead of introducing a new one.

Changed since v5:
 - Fix format

Changed since v4:
 - Introduce slub_debug_enable_unlikly() to check the debug state.
 - Include "slab.h" and Add slub_debug_enable_unlikly() to lead
   the condition statement.
 - Add comment block about this new code path in source code.

Changed since v3:
 - Apply IS_ENABLED to wrap codes under SLUB debug mode.
 - Replace memset() by memzero_explict().

---

Marco Elver (1):
  mm: move helper to check slub_debug_enabled

Yee Lee (1):
  kasan: Add memzero int for unaligned size at DEBUG

 mm/kasan/kasan.h | 12 ++++++++++++
 mm/slab.h        | 15 +++++++++++----
 mm/slub.c        | 14 --------------
 3 files changed, 23 insertions(+), 18 deletions(-)

-- 
2.18.0
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