kasan: add memzero init for unaligned size at DEBUG

Issue: when SLUB debug is on, hwtag kasan_unpoison() would overwrite the
redzone of object with unaligned size.

An additional memzero_explicit() path is added to replacing init by hwtag
instruction for those unaligned size at SLUB debug mode.

The penalty is acceptable since they are only enabled in debug mode, not
production builds.  A block of comment is added for explanation.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Yee Lee <[email protected]>
Suggested-by: Andrey Konovalov <[email protected]>
Suggested-by: Marco Elver <[email protected]>
Reviewed-by: Marco Elver <[email protected]>
Reviewed-by: Andrey Konovalov <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: Alexander Potapenko <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Nicholas Tang <[email protected]>
Cc: Kuan-Ying Lee <[email protected]>
Cc: Chinwen Chang <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions