Re: [PATCH v2 1/1] kasan: Add memzero init for unaligned size under SLUB debug
From: Marco Elver <elver@google.com>
Date: 2021-06-28 18:42:12
Also in:
linux-arm-kernel, linux-mediatek, lkml
Possibly related (same subject, not in this thread)
- 2021-06-23 · Re: [PATCH v2 1/1] kasan: Add memzero init for unaligned size under SLUB debug · Yee Lee <hidden>
- 2021-06-23 · [PATCH v2 1/1] kasan: Add memzero init for unaligned size under SLUB debug · <hidden>
On Thu, 24 Jun 2021 at 13:27, [off-list ref] wrote:
quoted hunk ↗ jump to hunk
From: Yee Lee <redacted> 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. Signed-off-by: Yee Lee <redacted> --- mm/kasan/kasan.h | 6 ++++++ 1 file changed, 6 insertions(+)diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index 8f450bc28045..d1054f35838f 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h@@ -387,6 +387,12 @@ static inline void kasan_unpoison(const void *addr, size_t size, bool init) if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK)) return; +#if IS_ENABLED(CONFIG_SLUB_DEBUG)
Avoid the #if. I think none of the stuff referenced here is only
available if CONFIG_SLUB_DEBUG. In that case, please just write:
if (IS_ENABLED(CONFIG_SLUB_DEBUG) && init && .........) {
The compiler will correctly optimize out the branch if the config
option is not enabled. But the benefit is we compile-test this code
with all configs.
+ if (init && ((unsigned long)size & KASAN_GRANULE_MASK)) {
+ init = false;
+ memzero_explicit((void *)addr, size);
+ }
+#endifThanks, -- Marco